Entries tagged "aboutpaleo"

My prettier half and I have been engaged in a rather significant shift in our diet, and many of our friends, because they're awesome and are doing what friends do, expressed concern about it. For several months she and I have been eating in accordance with a diet called the Paleolithic Diet, or "Paleo". For the last three weeks, we've amped up our efforts as part of Potomac Crossfit's Paleo Challenge - eating strictly Paleo for 5 weeks and aiming toward shifting our bodies into ketosis (to be explained in this series). So to help our friends and family understand better what we're trying to do and why we think it's a good idea, I'm presenting this multi-part series on eating Paleo and trying the Paleo Challenge.

It Stands to Reason...

As capable as the human mind is, it's extremely bad a comprehending large numbers. Sometimes we need clever or funny demonstrations to really comprehend them. This is particularly true with time.

Let's imagine that the time since the earth's formation is a 24 hour day. Here are when various events would have happened:

• 4:00am: First single celled life appears
• 2:30pm: First complex cells appear - cells with nuclei and other organelles
• 6:45pm: First multi-celled bacteria appear
• 10:40pm: Dinosaurs appear
• 11:39pm: Dinosaurs go extinct
• 11:59:12pm : First proto-humans appear
• 11:59:59.8pm : Invention of agriculture and dawn of civilization

If you live to be a hundred years old, your lifetime in this scale would be 0.0018 seconds of time. By means of comparison, a blink of an eye is somewhere between 0.3 and 0.4 seconds, so over 200 people could live 100 year lives in the time it took you to blink.

Time stretches on longer and further than you could ever imagine. However long you can imagine is a mere pittance to reality.

Let's adjust our scale and imagine the time since the first proto-humans walked the earth is the 24 hour day. On this scale, the invention of agriculture occurs at 11:54pm. From the beginning to six minutes before midnight, humans subsisted on a diet of fruits and vegetables, meats, eggs, nuts, and seeds. In the last six minutes, we added to our diet grains and dairy products as we began to cultivate cereals and master animal husbandry. And at 11:59:56pm, we began to unmake the fabric of our diet shifting nearly all emphasis to cereals and cereal-derivatives.

It stands to reason that as natural selection functions, humans spent those first 11 hours and 54 minutes evolving to operate most effectively on the foods readily available to us - the fruits, vegetables, meats, eggs, nuts, and seeds. It defies logic to imply that in the six minutes since then we've somehow evolved to adapt to a diet high in cereals, grains, and dairy products - evolution simply does not work that quickly. So philosophically, since anatomically and biochemically we are identical to our paleolithic ancestors, it would make sense if we were best suited to subsist on the same foods they ate. It remains to be seen if the science supports that line of reasoning.

Go on to part 2 - "What changed in the last 20 years that made us fat?"

This is part 2 in a series. Part 1 - Entire series

What Changed That Made Us Fat?

In my profession as a systems administrator, one of the many hats I wear is as a troubleshooter. Something breaks that always worked before, and we're not quite sure what broke. The first question we generally ask is, "What changed?" Most of the time there was some unrelated change that was made to the system that coincided with the breakage or preceded it by some reasonable margin - and by identifying that contemporary change, the underlying problem is often discovered.

The obesity epidemic we hear about every day in the news really only started about 30 years ago. The NIH and CDC have compiled the various surveys and found that from 1960 to the late 70's, obesity in the United States was fairly fixed. Somewhere around 1980, it started trending upward, and it hasn't stopped.

So what changed? With the standard caveats about correlation and causality, I'd like to suggest a series of major shifts in our diet that I believe hit a critical threshold in the late 70's that toppled us over.

At the beginning of the 20th century, the food landscape was very different. Refrigeration was just beginning to be introduced, but it would not be found in homes until the late 1930's - however refrigerated train cars began eliminating seasons from the markets as food could be transported long distances while staying fresh. Many of the household brands we know of today were becoming national brands, like the National Biscuit Company (Nabisco), Campbell's, General Mills, Quaker, and Kraft. Diets consisted of a mixture of fresh and preserved meats, dairy (evaporated or sweetened-condensed when fresh was unavailable), cereals and breads, and fruits and vegetables.

Oh, and also corn liquor. Massive quantities of corn liquor. This country loves to drink and always has. We drank liquor at every meal. We drank before, during, and after work. According to W.J. Rorabaugh, our present tradition of the morning coffee break derives from what used to be a late-morning whiskey break. In the 1820's, an American man on average drank a half pint of liquor a day. And farmers enjoyed supplementing their income by distilling their extra grains into the sauce. Liquor taxes were up to 40% of the tax revenue for the Federal government prior to the passage of the 16th amendment in 1913. And according to the Smithsonian Magazine, the passage of the 16th amendment, authorizing the Federal government to levy a general income tax, cleared the way for the 18th amendment passed in 1919. And prohibition began.

Suddenly, the giant market for grain alcohol disappeared, and demand for grain decreased relative to supply. In most markets, this is not a problem - natural price pressures in the face of waning demand encourage producers to decrease production, and prices stabilize. The agricultural market strangely does the opposite. When the price of grains drops at the market, farmers grow extra yield to attempt to make up the difference - and supply goes up instead. Ingenious inventors and ambitious salesmen developed new industrial machinery to help give the farmers continually greater yields at comparably lower costs. Supply continued to rise, demand continued to stagnate.

And then the Depression hit. Demand fell. Prices went to zero.

It took heavy handed interventions from Roosevelt and the New Dealers to bring this overproduction under control. The problem was farmers overplanting to prevent falling prices from lowering their incomes. Under the new farm policy, the USDA set a target price for all storable cereals as a function of actual cost of production. If the prevailing market prices for those grains dropped below the target, farmers could take out a loan from the government using the crops as collateral. Over the course of the year, if the market improved, the farmers would sell the grain, pay back the loan, and move on. If the market failed to improve, the government would forgive the loan, take the collateral, and store it in its own granaries as a Federal grain reserve. If prices subsequently spiked due to a poor harvest or other unforeseeable conditions, the USDA would supplement the market supply with its own reserves. Prices and production levels stabilized, and grains remained abundant and cheap.

From the 30's to the 70's, this farm policy remained in place, but it became less relied upon. The market continually devised new uses for this enormous supply of grains, and farmers continually expanded their yields to meet this new demand. Livestock farmers had always used grains as a finisher for their meats - it was well known that grains fattened the animals before slaughter. More meat meant more money. But with grain prices so low, post-WWII demand for meat on the rise, farmers used more and more of these storable cereals as their animal feed until grass-fed became the oddity. A new process of oil extraction by using solvents like hexane led to the cheap, mass production of cooking oils from grains - cheaper and more efficient than the prior method of pressing oils.

And it all culminated in the early and mid 1970's.

In 1972, President Richard Nixon announced that he had brokered a deal with the Soviet Union to create an exception to our broad economic embargo of the USSR and permit them to purchase $750m of grains over the course of several years. The Soviet Union's domestic agriculture production was insufficient to feed its population, and Nixon saw the grain sale as both a humanitarian imperative and as an opportunity to improve the US standing in the Cold War. However, the Soviets exceeded their total purchasing quota in the first year. The US grain market might have been able to absorb the added demand without a price spike, but the farm belt experienced a coincidental spell of bad weather lessening expected crop yields. Food prices surged, including meats and dairy whose production now depended upon a surplus of cheap grains.

Nixon ordered the USDA to employ drastic measures to get food prices under control. Secretary of Agriculture Earl Butz dismantled the New Deal-era farm policy and instead implemented a new subsidy program that instead of nonrecourse loans relied upon direct payments to producers. Farmers received a check from the government, and were free to dump their grains on the market regardless the price they fetched. In the immediacy, grain prices fell, but the new policy shifted the economics of agriculture radically. Farmers received direct subsidies based on yield, and as such had a perverse incentive to overproduce. Agribusiness companies began consolidating farms in order to minimize production costs but maximize the yields and profits.

Then came sugar. In 1937, the Federal government passed the Sugar Act which dictated the system of import duties and quotas for cane sugar based on the assumption of a world surplus in sugar. The energy crisis, inflation, and global commodity shortages made that assumption invalid - sugar consumption exceeded production from 1970 to 1974, and sugar prices climbed to 57 cents per pound. The Sugar Act which had been extended continuously by the Congress since its enactment was allowed to expire in 1974, and just three years later, the price of sugar fell to 8 cents per pound. A new system of tariffs and quotas was implemented in 1977, and sugar prices in the United States began to climb again. With the newly swelling surplus of corn being produced, US food producers began replacing sugar with a chemical substitute invented in 1957 - high fructose corn syrup. By 1985, individual consumption of HFCS grew to 45 pounds per year.

As these shifts were happening in the late 1970's, the predominant nutritional paradigm was also shifting. In the 1950's, Dr. Ancel Keys of the University of Minnesota in introduced a theory that a diet high in fat raises cholesterol levels and promotes heart disease. Researchers tested this hypothesis over the succeeding decades but the evidence was ambiguous - some studies positively correlated a high fat diet with higher cholesterol and cardiovascular disease while others found no such positive correlation. When science is unable to come to a consensus on the issue, as it often happens politics takes over. In 1977, Senator George McGovern led a committee to publish "Dietary Goals for the United States" which modified the guidelines in place since 1941 to advise Americans significantly reduce their fat intake to avoid "killer diseases" they alleged were sweeping the country. The NIH got on board in 1984, recommending that all Americans over the age of 2 eat less fat. The Center for Science in the Public Interest called fat "the greasy killer". Government pronouncements as such create headlines, and headlines alter market trends - food manufacturers highlighted their low-fat, high carb products. The low-fat, high carb recommendation was canonized in the 1980 USDA Dietary Guidelines publication and again in the 1992 publishing of the "Food Pyramid" - 6 to 11 servings of grains and cereals per day, use of fats and oils "sparingly".

The NIH has spent hundreds of millions of dollars in the intervening years trying to establish a conclusive connection between eating fat and getting heart disease. Out of the six major studies, five showed no such connection. The sixth conclusively demonstrated that statins, a prescription drug intended to minimize cholesterol imbalances, could prevent heart disease. The conclusion drawn by the NIH was that, even though they had failed to demonstrate that a low-fat diet had any health benefits, if statins could lower cholesterol and prevent heart attacks, a low-fat diet should do the same.

Instead during this time, we've seen historically unprecedented increases in the frequency of obesity, diabetes, heart and vascular disease, asthma, depression, liver and kidney failure, and cancer.

In the last ten years, nutritional scientists have been collecting an increasing corpus of data that strongly suggests the low-fat, high-carb strategy isn't just wrong - it's killing us. And the nutritional prescriptions that come out of this body of evidence tend to conclude that the fuels and nutrients that help our bodies function best are the ones that our paleolithic ancestors lived on for millions of years. I'll discuss those prescriptions and the evidence found in part 3 of this series.

Go to part 3 - "The Science of Paleo"

The Science of Paleo - Carbohydrates, Insulin Metabolism, and Fiber

This is part 3 in a series. Part 2 - Entire series

Our history textbooks teach us the origination of the scientific method in the period of Enlightenment when reason once again began to counter mysticism and superstition, when humankind began to deduce the functioning of the natural world through controlled experimentation. Physics and astronomy are as old as the classical age. Enlightenment Europe unraveled the mysteries of electromagnetics, fluid dynamics, and chemistry. We do have to remember though that some sciences are relatively new. Psychology only really fell under science's purview in 1890 with William James' book The Principles of Psychology. So it deserves mention that the study of endocrinology is even more youthful. The term hormone wasn't coined until 1902. A Nobel Prize was awarded in 1921 for the discovery of hormones in neurochemistry. The study of molecular endocrinology began as late as the 1960's.

At the time when the low-fat/high-carb diet prescription was made, the relationship between diet and hormonal responses was not even conceived, and the human body was effectively a black box - we could see how putting something in seemed to change what came out, but we had no concept of the mechanization inside. The last two decades have changed that substantially, especially in our understanding of insulin.

Insulin is a Double-Edged Sword

Insulin is a hormone secreted by the pancreas that almost singlehandedly regulates the energy metabolism of glucose. Unless you're diabetic, you're probably not aware of just how much insulin does, and if you're not diabetic, you probably don't even think about your insulin levels at all. So let's change that. Here's how digestion and energy metabolism works for somebody on the standard Western diet.

1. You eat food, and if your diet includes grains, sugars, and dairy, your stomach breaks down those carbohydrates into the simple sugar glucose. Glucose enters your bloodstream from your stomach.
2. Your pancreas, detecting climbing levels of blood sugar, secretes insulin.
3. Insulin signals your muscles and adipose tissues (fancy way of saying body fat and connective tissue) to suck that glucose out of your blood and store it as glycogen - a molecule that can be stored in the cells and used for energy. This works because your cells have in their outer walls insulin receptors which catalyze this response - insulin binds with the receptors, and the cell uptake of glucose from the blood increases.
4. As blood glucose levels drop, the pancreas shuts off the insulin valves.

Sounds pretty simple and easy, but it turns out that insulin actually does a lot more than that.

1. Insulin increases fatty acid synthesis and storage . Whatever fat you consumed at the same time you consumed this sugar, insulin causes your adipose tissues to take in the fatty acids you digested and store them to triglycerides. We'll hear more about trigylcerides later.
2. Insulin directly impacts the "satiety" mechanisms in your brain, that is it tells your brain you're not hungry anymore. Drops in your blood sugar cause the opposite effect.

Knowing what we know about the diet that our paleolithic ancestors relied upon, this makes perfect and total sense that insulin works like this. Early humans consumed foods that were low in sugars that break down easily into glucose - their diet was low glycemic. Wild fruits were not as sweet as our modern bred varieties, honey was a rare treat that required fending off bees to obtain, and cereals were simply not refined and consumed. If a hunter-gatherer did happen to stumble upon a sudden splurge of moderately glycemic foods, their metabolism would run off that sugar and replenish cells' supply of glycogen while storing the fats in the diet. Insulin would shut off the brain's hunger mechanism, and a few hours later when the sugar was burned off, that stored fat would be burned as fuel.

That all sounds great. Unfortunately, our bodies have a defect in their insulin metabolism. Even evolutionary code gets bugs.

When endocrinologists observe the pancreas' secretion of insulin, what they notice to be odd is that the pancreas actually secretes insulin in spurts. Insulin levels in the blood fluctuate every few minutes between highs and lows until the blood sugar has stabilized. The reason for this is that the insulin receptors in our brain and in our adipose tissues easily develop a resistance to insulin - for whatever reason, they stop binding to insulin. So the pancreas evolved to continually change the insulin secretion rate in order to prevent insulin resistance.

With a high-carbohydrate, high-glycemic diet this defect effectively pre-ordains obesity. The more adipose tissue you have, the more insulin your pancreas will release in response to blood sugar increases. The more insulin in your blood, the faster your cells become insulin resistant and the longer that insulin resistance lasts. The more insulin resistant your brain, the less your brain can signal your body that you're full. The more insulin resistant your cells, the more insulin your pancreas will secrete. The more insulin the pancreas secretes, the more the body stores dietary fat and the more adipose tissue is created - which makes the next iteration of the cycle even worse.

The breakdown of the insulin metabolic cycle leads to a host of health issues the medical community called "Syndrome X" or "metabolic syndrome". Metabolic syndrome includes obesity, high blood pressure, poor blood cholesterol profile, and elevated blood glucose levels. Combined, these conditions massively raise a person's risk of type-2 diabetes, atherosclerosis (artery clogging) that leads to heart attacks, cardiac arrhythmia (irregular heart beat), hypertension, gout, and ulcerative colitis.

I was a vegetarian for 5 years, and I experienced almost daily the sensitivity of insulin metabolism, and you may have experienced something similar. I eliminated meat from my diet and to make up the missing calories, I ate a lot more grains. About two hours later, I felt light headed, my hands would shake, my skin would flush, and I felt close to passing out - my blood sugar had crashed, and I was experiencing hypoglycemia. In response I had to eat more - and usually something high glycemic to raise my blood sugar quickly, like juice. My hypoglycemia was rather extreme - if you've ever felt cranky when you haven't eaten for awhile, sluggish around mid-afternoon in the workday, extreme hunger pangs a couple hours after eating something carb rich, or a complete crash after drinking an energy drink, you're probably experiencing hypoglycemia.

The insulin response certain foods generate depends on their glycemic index or GI. The glycemic index describes how quickly a particular food will generate a glycemic response. Foods with a high glycemic index generate a high insulin response, and as such, blood sugar levels can drop below where they were before you ate - hypoglycemia - prompting you to eat more. Eating foods with a more moderate glycemic index permits more gradual insulin secretion and avoid the "crash" afterward.

This understanding of insulin metabolism clearly shows that our bodies function optimally when we avoid spiking our blood sugar and consequently our insulin levels. This means we must minimize the glycemic load in our diet.

Glycemic Load and Glycemic Index of Common Foods

Food	Glycemic Index	Glycemic Load
Beef	0	0
Chicken	0	0
Eggs	0	0
Pork	0	0
Broccoli	6	1
Asparagus	8	1
Spinach	6	1
Tomatoes	6	1
Cantaloupe	63	9
Apple	38	8
Banana	51	14
Corn Flakes	92	24
Donut	78	17
Croissant	76	17
Coca-cola	63	16
Baguette	95	15
Bagel	72	25
Wheat bread	58	12
Grape Nuts	75	16
Brown rice	50	16
Basmati rice	58	22
Potato	85	26

Glycemic load is directly related of both the glycemic index (how fast the blood sugar will rise) and how carbohydrate rich a portion of that food is (higher carb density will cause higher blood sugar levels). Taking into account carbohydrate density is important -- watermelon has a high glycemic index but it's relatively low in sugar density, so it has a low glycemic load. A glycemic index below 55 is low and above 70 is high. A glycemic load below 10 is low and above 20 is high.

From looking at the table, it's pretty clear that cereals and grains have very high glycemic loads while meats and vegetables have next to zero glycemic load. Even "sweet" fruits like apples don't compare with foods like corn flakes when it comes to impact on insulin metabolism. Any added sugar and sweeteners like high fructose corn syrup only makes glycemic load in the diet worse.

But don't we need grains?

The FDA recommends that a healthy diet should have between 45% and 65% of the calories from carbohydrates, a fat intake between 20% and 35% of calories, and a protein intake of between 10% and 35% of calories. Anthropologists conclude that this calorie breakdown is starkly different from what humans ate prior to the agricultural revolution 10,000 years ago. Their calorie breakdown was 22% to 40% carbohydrates (mostly dietary fiber), 28 to 47% fat, and 19 to 35% protein. In practice, Americans get about 50% of their calories from carbohydrates, about 35% from fat, and about 15% from protein. That's a pretty stark difference - our ancestors lived on far more fat and protein in their diet than we do.

For example, the Inuit, living in barren Arctic lands, subsisted on a diet of seal, whale, walrus, and berries. Their caloric breakdown was 30-40% of their calories from protein and 50-75% of their calories coming from fat, but they did not have high blood pressure or cardiovascular disease as those on the standard American diet do. Even the last remaining modern hunter-gatherer tribes, such as the Sentinelese of India or the Spinifex of Australia, continue to subsist on low carbohydrate diets.

Grains, it turns out, just aren't that nutritious - even if you eat "whole grains". The primary nutrient touted in whole grains is dietary fiber. Fiber generally is considered pretty good to have in your diet. High fiber foods have lower glycemic indices because fiber slows the absorption of glucose. Fiber also improves your blood cholesterol profile, improves regularity and consistency of bowel movements, and improves intestinal absorption of vitamins and minerals. Beyond that, fiber is filling - it makes you feel full. But grains, even "whole grains", have a pittance of fiber compared to fruits and non-starchy vegetables. Per 1000 calories, refined cereals have 6 grams, whole grain cereals have 24 grams, fruits have 41 grams, and non-starchy vegetables have 185 grams of fiber. You can get 4.5 times the fiber density in a vegetable like broccoli than you can in a whole grain cereal.

Other than fiber, grains are so lacking in vitamins and minerals that we've actually historically had to consciously add vitamins and minerals to compensate for pandemic vitamin deficiencies. We add folic acid to white flour and refined grains to ward off heart disease, colon cancer, and spina bifida in newborns. We add thiamin (vitamin B1) to rice and breakfast cereals because of population wide increases of beriberi, which causes paralysis. We add B6 and B12 to our cereals to reduce homocysteine levels in the blood which can cause heart disease. We add biotin (vitamin B7) for strong fingernails and healthy hair. We add niacin (vitamin B3) to prevent pellagra after there was an epidemic from 1906 to 1940 in the American south. Each of these vitamins occurs naturally in meats, fruits, and vegetables - but not in grains.

To make matters worse, grains even have anti-nutrients - poisons that actually counteract the body's ability to absorb nutrients. Grains contain three toxins evolutionary biologists believe were defense mechanisms meant to discourage other animals from eating them: lectins, gluten, and phytates.

Lectins (also naturally occurring in beans and other legumes) are highly toxic - in fact the biochemical weapon ricin is a lectin extracted from the castor bean. We soak beans in water for long periods of times to minimize their lectin content. Lectins bind to insulin receptors to promote insulin resistance, increase permeability of the intestinal lining to allow bacteria and undigested food to enter the bloodstream triggering an autoimmune reaction, and increases the body's resistance to leptin, the hormone that signals satiety to the body and controls hunger.

Gluten, found in many kinds of grains, causes inflammation in the intestine and an auto-immune reaction. While only 1% of the population has full-blown Celiac disease, almost all people have a milder reaction to gluten that, over time, massively increases risks of heart disease and cancer. In most people, this gluten intolerance manifests itself as side-effects - osteoporosis, irritable bowel syndrome, anemia, cancer, fatigue, and autoimmune disorders from the most virulent like MS or lupus to the most mild like alopecia. The autoimmune reaction people have to gluten causes inflammation all over the body - in your joints, your organs, and your muscles.

Phytates make the intestines unable to absorb vitamins and minerals, counteracting the benefit provided by the associated fiber intake of grains and minimizing the benefits of the fortification of the grains to begin with.

The bottom line is that grains are far too carbohydrate rich, far too nutrient poor, and far too toxic for them to be healthy to consume. They're cheap, they're easy to cultivate, and they're storable, which is why the population and technology explosion of the modern age was possible. However, given the pervasiveness of grains and grain-derived products in our diet, it's a major underlying cause of the general ill health of the western world.

Next in part 4

We've talked a lot in this part about insulin metabolism and some specific issues with the lack of nutrition in grains. Mostly, this has focused on carbohydrates - glycemic load and dietary fiber. In our next installment we'll focus on the most controversial macronutrient in our diet: fats.

This is part 4 in a series. Part 3 - Entire series

The Science of Paleo - The Misunderstood Macronutrient

One of my general frustrations with the public policy and advocacy of nutritional information is that if nutritional advice can't be distilled down to a single sentence, it won't be able to reach and inform a wide audience, but if it does get distilled down to a single sentence, it loses so much accuracy it's not necessarily helpful. Nowhere is that more true than with fat.

Among popular understanding of nutrition and even among some nutritionists, fats are a pejorative, and we have an awful love/hate relationship with them. Bottom line is we need fat. It makes up the membranes and connective tissue of every cell in our body. It insulates us and keeps us warm. It provides protective cushion around our vital organs. And it is the most energy-dense nutritional molecule we can process. But when we carry too much excess body fat, or adipose tissue, it seems incredibly difficult to get rid of and it forebodes the onset of a plethora of diseases. Common sense and common dietary advice has for decades prescribed that if you eat less fat, you'll be less fat. The reality is not quite so simple.

While our understanding of carbohydrates, fiber, and insulin metabolism has grown quite mature, our understanding of fats and their role in various biomechanics is relatively elementary. We have identified specific functions of specific types of fats, but for the most part our understanding of dietary fat's impact on our health operates can only be described in "black box" statements -- we know that if you put this much of this kind of fat into your body, certain results are likely to follow, but we don't really know why or even if the dietary fat are causal or correlative. So even among nutrition scientists, wrapping our heads around fats and what they do means sifting through a lot of vague and contradictory black box studies. So let's do some sifting, but first I want to talk about two major health concerns that come along with fat - obesity and cardiovascular disease.

Does Eating Fat Make You Fat?

Body fat, or adipose tissue, is just loose connective tissue - cells that serve as warehouses for excess fat. These warehouses insulate the body from cold and store energy for when it's needed later. Humans store body fat in very specific areas called adipose depots. Body fat that collects under the skin (subcutaneous fat), around the abdomen protecting internal organs (visceral fat), in bone marrow, and around the breasts (yes, even in men). Women have additional adipose depots in the buttocks and thighs, due to sex hormone differences.

The simple relationship with caloric intake and body fat development basically holds true - if you consume more calories than you burn off or excrete, you'll store the excess as fat, and if you consume fewer calories than you burn off or excrete, you'll rely upon your stored fat to make up the difference. As with all things nutritional, it's a little more complicated than it seems.

First, the rate at which we burn off calories is not constant. Our rest metabolic rate shifts throughout the day depending on how much we've eaten, what we've eaten, and our body composition. Your metabolic rate is in fact the lowest when you simply don't eat - your body goes into a conservation mode and only expends the minimum base of energy necessary to keep vital organs functioning, which is why you may have heard people say that skipping a meal may not actually help you lose weight at all. Some foods require more energy to digest than others - fiber and protein require the highest amount of energy to process while dietary fat requires the least. Correspondingly, different types of tissue in your body require different levels of energy to maintain - more lean muscle increases your metabolic rate far more than adipose tissue does. so while exercise does increase your metabolic rate during exercise, it has not been shown to raise your base metabolic rate, however if your exercise includes resistance training that builds additional lean muscle mass, your base metabolic rate should go up.

Second, what you eat and when changes how your body processes those calories. As we discussed in the previous section, when your blood glucose levels rise, your pancreas secretes insulin to signal your cells to process that glucose, but at the same time that insulin signals your cells to take any fats you've just eaten and store them away in adipose tissue. Absent this insulin spike, fats will be metabolized and used as energy so much as they're needed. This is in part why obesity is so common in a high carbohydrate diet, even though it's relatively low in fat - all of those fats just get stored away.

As visceral fat buildup grows, we start to fill out around the midsection and grow a gut. Once visceral fat buildup begins, it can easily go from bad to worse very quickly - if you're slightly pudgy, it's a lot easier to get fatter than it is to get slimmer. The reason is that fatty adipose tissue also releases hormones, and visceral fat is more hormonally active than most - releasing more adipokines and resistin than other fat cells. Increased adipokines can cause glucose tolerance - glucose levels in the blood remain high despite the presence of insulin, and increased resistin can cause insulin resistance - reduced glucose uptake into cells despite high presence of insulin. High levels of glucose and insulin in turn cause you to store more fat, creating more visceral fat buildup, complicating the problem further. It's no wonder that high visceral fat amounts are very positively correlated with metabolic syndrome - cardiovascular disease, type-2 diabetes, and more.

Stress makes matters worse. When you're stressed out or panicky, your body releases a hormone called cortisol which, evolutionarily, primes your body for physical exertion anticipating the stress has a life-threatening environmental cause. If you've ever watched Star Trek, it's your body's way of calling out "red alert". Normal function shifts, and everything moves toward self-preservation. The activity of your digestive system, reproductive system, and immune system shut down. Mental acuity goes up for storage of short-term emotional events. In our modern life where stress comes from deadlines, rush hour, and bills rather than lions, tigers, and bears, these biological responses over time have sharply negative consequences. Cortisol breaks down collagen in the skin, which is why you look tired and aged when you're overstressed. And the digestive system shutdown drives your body to store energy as fat rather than consume it, which is why they say that stress can make you fat.

Cholesterol and Artery Cloggage

Another massive oversimplification comes from the dietary guidelines on cholesterol. Thirty years ago, the prescription was to simply keep your blood cholesterol level down below 200mg/dl. Around ten years ago, the prescription gained a nuance in differentiating between your HDL levels ("good" cholesterol) and your LDL levels ("bad" cholesterol).

The first problem with that is that there's really only one kind of cholesterol. Cholesterol is a kind of fat, and it's absolutely essential that your body have cholesterol. It's a critical component for making cellular membrane, bile acid, certain steroidal hormones, and certain vitamins. Cholesterol has to be transported around your body by your bloodstream, but since cholesterol is oily and your blood is water, cholesterol is not soluble in blood, so it requires a transport molecule called a lipoprotein. Lipoproteins also transport other fats around your body stored as triglycerides. The amount and makeup of the fats carried in the lipoproteins affect its density. High-density lipoproteins (HDL) are cholesterol hungry, and in the presence of excess cholesterol in cells or in the bloodstream, HDL will suck up that cholesterol and transport it to the liver and steroidal glands (like the adrenal gland, ovaries, or testes) for other uses. Low-density lipoproteins (LDL) transports cholesterol from the liver to cells around the body as they need them.

So why would having more LDL be bad? Basically, doctors and nutritionists have observed that people who have high levels of LDL and lower levels of HDL are more likely to develop atherosclerosis - the development of fatty deposits on the interior of your arteries that can cut off blood flow or release clots, causing heart attacks, aneurysms, or strokes. The fats in LDL, like many fats in the body, can become oxidized by the presence of free radicals. When oxidized LDL bounces off an arterial wall, it causes inflammation and the immune system gears up to respond. White blood cells called macrophages attack and absorb the oxidized LDL but cannot process them. The macrophages rupture, spilling oxidized cholesterol into the bloodstream. These ruptured macrophages and oxidized cholesterol are sort of "sticky", and once released they stick to the arterial wall causing further inflammation. More macrophages are summoned, and the process repeats. When these sticky foam cells accumulate in a single spot, they begin to form an atheroma. Calcium in the blood bonds to the outside of the atheroma, and a hard cap forms on the outside. The atheroma can cause sufficient inflammation to close off the artery or the atheroma can burst, releasing the hard cap into the blood stream and potentially causing a harmful clot. Since HDL is cholesterol hungry, it interrupts this cycle because it absorbs and delivers to the liver the free-floating oxidized cholesterol, reducing the risk of a cardiovascular event.

If we look at this logically though, we see there isn't a causal relationship that can be established. People who have higher levels of LDL and lower levels of HDL tend to be at higher risk for atherosclerosis. But that doesn't mean having high LDL and low HDL causes atherosclerosis, and it seems like it's the oxidation of LDL by free radicals and the inflammation of the arterial wall that is a necessary condition for atherogenesis - the creation of an atheroma. And while it may seem like common sense that increasing your dietary cholesterol increases your blood cholesterol, there has not been a clearly established causal link - and in fact in some studies raising dietary cholesterol decreased blood cholesterol.

So if we're aiming to minimize our risk of atherosclerosis, we ought to:

1. ... eat foods that optimize our blood cholesterol profile - higher HDL and lower LDL.
2. ... make sure our diet is rich in antioxidants to counter the harmful effects of free radicals.
3. ... make sure our diet has anti-inflammatory properties, not inflammatory ones.

Know Your Fats

Almost fats we eat are composed of three fatty acids joined by a module of glycerol to form a triglyceride molecule. But not all fatty acids are the same, and they have wildly different properties. There are seven main kinds of fatty acids, and nutrition scientists have been able to make black-box observations about their effects on blood cholesterol profile, susceptibility of LDL to oxidation and macrophage uptake, inflammatory/anti-inflammatory properties, and general risk of cardiovascular disease, and since they're black-box and subject to interpretation, I'm actually going to cite studies for your own edification.

Trans-isomer Fatty Acids

While some trans-isomer fatty acids appear in nature, the vast majority of the ones in a human diet are manufactured. An unsaturated fat (a fat not fully stocked with hydrogen atoms but instead with some double bonds remaining) is chemically processed with additional hydrogen atoms to increase its saturation to partially or fully hydrogenation. The structure of the resultant trans-isomer fatty acid, or "trans fat" for short, is more resistant to rancidification so it lasts longer without spoiling and is solid at room temperature. Trans fats were first introduced into the market in 1911, as the Procter and Gamble Company brought to market its crystallized cottonseed oil, or Crisco. The predominant cooking fat at the time was lard, beef tallow, or butter, but Crisco's inexpensive cost and longer shelf-life quickly made it a popular commodity.

However, trans fats cannot be processed by the enzymes in the body due to their unique structure. The enzyme lipase, which is essential in digestion and transportation of fats in lipoproteins, is ineffective on trans-isomer fatty acids, and so lipoproteins containing trans fats remain in the blood stream for longer periods of time, rendering them more likely to be oxidized, to deposit themselves in the arterial walls, and contribute to plaque formation. Concentrations of LDL increase with dietary trans fat intake and concentrations of HDL in the blood decrease.

It is because of the clearly and unambiguously deleterious effects of trans fats on your health that there has been such a backlash against their presence in foods. Trans fats are found in shortening and margarine - the best way to tell is to look at ingredients. If you see "hydrogenated vegetable oil", partially or fully, there are trans fats lurking within. Your diet should be free of trans-fat, if possible. There are no redeeming nutritional effects to consuming them.

Saturated Fatty Acids

Next to trans fats, saturated fats receive the most disdain from nutrition scientists, and for good reason. But it depends on what kind of saturated fatty acid. There are four we find in our diet: stearate, laureate, myristate, and palmitate. They operate on our bodies with different effects.

Palmitate is why saturated fats get such a bad reputation - seldom do you see the term "saturated fat" without the descriptor "artery clogging". Palmitate lowers HDL and raises LDL. There are many hundreds of studies all indicating the link between saturated fat and poor blood cholesterol profiles, however in the western diet, this means palmitate. Palmitate is the primary saturated fatty acid in grain-fed animals, both their meat and their dairy products. A number of studies that focused on populations with rich saturated fat content in their diet but low palmitate content found low incidences of cardiovascular disease. Palmitate is the culprit.

Stearate seems to be neutral with regard to blood cholesterol profile and beneficial at reducing unhealthy clotting. Laureate and myristate, which consists of up to 60% of the energy in the diets of certain Polynesian populations have no harmful cardiovascular effects from so much saturated fat.

So the saturated fats found in the tropics in coconut, palm, and palm kernel oil seem to be fairly neutral for consumption. The saturated fat in grain-fed meat and dairy seem to be problematic in increasing our risk for cardiovascular disease.

Monounsaturated Fatty Acids

Monounsaturated fats are healthful. Monounsaturated fats have been found to reduce LDL oxidation and inhibit macrophage uptake, which helps prevent atheroma formation. When substituted for saturated fats or carbohydrates in the diet, monounsaturated fats can combat insulin resistance and improve blood cholesterol profile. It also can reduce the risk of harmful blood clots. Numerous studies of Mediterranean diets that differ from the macronutrient makeup of the standard Western diet note that with higher fiber and antioxidant intake and with much higher consumption of monounsaturated fatty acids, incidences of cardiovascular disease are far more rare than the rest of the Western world.

I'll say again though that these are all black-box studies - they look at what goes in and what comes out with no comprehension of mechanisms or causal relationships. Most of the studies cited above substitute monounsaturated fats for carbohydrates, omega-6 polyunsaturated fats, or the saturated fatty acid palmitate. That being said, monounsaturated fats have no harmful effects and even if they themselves are not cardioprotective, they appear to be very healthful in the place of omega-6 or palmitate.

Cooking oils rich in monounsaturated fats include olive oil and to a lesser extent canola oil. Avocados and some nuts, particularly macadamia nuts, almonds, and pecans, are rich in monounsaturated fats as well. Grass-fed meats and wild game contain far more monounsaturated fats and far less palmitate than grain-fed meats.

Omega-3 Polyunsaturated Fatty Acids

There are two families of omega-3 fatty acids - the awesome kind and the rock star kind. I can't really emphasize how unequivocally good for you omega-3 fatty acids are, yet 25% of Americans get zero measurable rock star omega-3 fatty acids in their diet. Zero.

The awesome kind is alpha linolenic acid, or ALA. Alpha linolenic acid has been shown to reduce heartbeat irregularities, and heart arrhythmias are very strong predictors of cardiovascular disease. It's been positively correlated with lower risk of heart attack and heart disease. And it can be used to synthesize a limited amount of eicosapentaenoic acid, or EPA.

Eicosapentaenoic acid along with docosahexaenoic acid, or DHA (challenge: say those five times fast!) are the rock stars. They are the principal fatty acids in brain tissue, so they're great brain food. EPA and DHA are anti-inflammatory, reducing arterial inflammation and free radical action. They reduce blood triglycerides and LDL. They help prevent the formation of atheroma. There's some indication they may reduce cancer risk and neurodegenerative disease risk. I'm sure given enough time they'll be shown to create world peace and balance the federal deficit.

EPA and DHA are found in cold-water seafood like salmon, mackerel, trout, sardines, and oysters. They're also found in the muscle tissue of grass-fed animals and wild game, however grain-fed animals are nearly devoid of EPA and DHA. Depending on the chickens' diet, some eggs can be decent sources of DHA and EPA.

Omega-6 Polyunsaturated Fatty Acids

Omega-6 polyunsaturated fats are primarily two different acids - linoleic acid, or LA, which is the shorter chain and arachidonic acid (AA) which is the longer chain. The modern Western diet is far richer in omega-6 fatty acids than our paleolithic ancestors' diet - whereas it is believed our ancestors had an omega-6 to omega-3 ratio of about 4:1, some Americans' omega-6 to omega-3 intake ratio is as high as 30:1.

The evidence on the impact of LA is mixed. In a study where monounsaturated fat and alpha-linoleic acid was substituted for LA and palmitate, incidents of cardiovascular disease went down sharply. One study suggested that LA reduced the frequency of atherosclerosis but there is some question regarding the accuracy of its methods. But a definite drawback to linoleic acid is that it interrupts EPA synthesis from ALA. All in all, you're probably better off limiting your LA intake. Arachidonic acid, while necessary for cell membrane manufacture and repair, has been demonstrated to promote inflammation - its effects are reduced with greater EPA concentrations in the diet.

Omega-6 fats are very highly concentrated in vegetable cooking oils, like safflower, sunflower, corn oil, cottonseed oil, and soybean oil, however there's another major concern with cooking with these oils besides omega-6 intake. Part of the reason polyunsaturated fats can be so inflammatory is they're especially prone to oxidation by free radicals. Polyunsaturated cooking oils, when old, exposed to sunlight, or heated at high temperatures, oxidize much more rapidly, and so consuming them basically begs them to do destructive damage to your body. Saturated fats like palm kernel oil or coconut oil are much more stable, even at high heats, and so are ideal for high heat cooking and deep frying. Polyunsaturated and monounsaturated fats like olive oil or walnut oil should only be used for medium temperature cooking -- no more than about 375 degrees.

Fat Selection by Food Selection

In summary, it seems like we want to ensure we get plenty of EPA and DHA in our diet, some measure of ALA, and fill the rest with monounsaturated fats and non-palmitate saturated fats. We want to limit our omega-6 intake and come as close as we can to eliminating trans fats and palmitate from our diet. Doing that should maximize our cardiovascular health and minimize our body's inflammatory responses. So what should we eat?

It sounds like we should avoid grain-fed meats, grain derived oils, and certain seed oils. Other oils offer more tangible benefits like olive oil, avocado oil, coconut oil, palm kernel oil, or grass-fed animal fats. We want to include cold-water seafood without incurring risk of mercury poisoning and pastured, grass-fed meats. Eating the right seeds and nuts also seems like good ways to balance out our fat profile.

Surprise, surprise - it's what our paleolithic ancestors would have done. And to reiterate once more, you can optimize your body's metabolism of fats by defending against harmful insulin spikes caused by too high of a glycemic load - doing that will ensure that your body burns the fats you eat instead of storing them.

Ketosis

Following the general prescription closely - minimizing foods rich in carbohydrates, maximizing foods rich in fiber, protein, and fat - will shift the very basis of your body's metabolism. Your body will switch from glycolysis (use of stored carbohydrate derivatives as its primary energy source) to ketosis (use of fatty acids as its primary energy source). Ketosis is not uncontroversial. Mainstream nutritional dogma believes ketosis to be the body's "starvation" mode as it turns to fat in the diet and in adipose tissue to find the energy it is not getting through carbohydrates in the diet. It is often argued that long-term operation in ketosis is unhealthful, but there has been no laboratory evidence of that. Furthermore, some hunter-gatherer cultures have existed almost entirely on ketosis with no noticable impairment of health or function.

The Paleo Challenge we underwent these last five weeks had the goal of inducing a ketogenic state. We deplete our bodies of glycogen and function primarily off of fat.

When the cells in the body have stored sugars (glycogen), the energy production system (Krebs cycle) burns that stored glycogen. Absent carbohydrate influx into the diet, those glycogen stores will be used up. The body then cleaves fat, both ingested and stored as triglycerides, into acetyl-coenzyme A which can also be fed into the Krebs cycle bound to oxaloacetate. In the presence of excess acetyl-CoA, the liver morphs them into chemicals called ketones. The brain cannot use fatty acids directly for energy, but it can use ketones. The brain converts the ketones back into acetyl-CoA for the brain to use for energy.

What this means is that the first two weeks aiming for ketosis suck. The brain takes awhile to adapt to using the ketones for energy as opposed to using them for fat synthesis, and during that time it runs as if it's low on fuel. We felt sluggish, spacey, grumpy, and less mentally acute. Our bodies had a tough time too - we had a harder time with strenuous exercise and we had a few rough nights of poor sleep. After those first two weeks, however, we felt perfectly fine on ketosis. Our mental acuity returned, our energy levels returned to normal, and our bodies functioned at a more regular, constant metabolism throughout the day.

That's not to say I recommend ketosis for everybody. It has its benefits, and from looking at my peers who also took the Challenge, ketosis led to some impressive instances of weight loss. But I fully recommend you do your own research and talk to a physician or dietician before considering aiming for a ketogenic state.

Continued in part 5: So what the hell do I do?

This is part 5 in a series. Part 4 - Entire series

So Now What the Hell Do I Do?

So what have we added up so far? There's a logical line of reasoning that suggests we'd expect our bodies to be evolutionarily optimized for eating the same things our paleolithic ancestors ate before the dawn of agriculture and animal husbandry 10,000 years ago. That means eating a diet of vegetables, meats, seeds, nuts, some fruit, very little starch, and no grains, dairy, or added sugars. Through a long series of independent studies conducted by scientists, there is a mounting pile of evidence that this line of reasoning is consistent with how our bodies seem to operate. The Paleolithic diet shows itself effective at preventing and even reversing the causes of obesity, insulin resistance, high blood pressure, high cholesterol, heart arrhythmias, clotting disorders, and digestive issues. There's initial evidence to suggest it's helpful in preventing or even reversing neurodegenerative disease, depression, cancer, autoimmune disorders, arthritis, osteoporosis, and a host of other illness. It's really a remarkably compelling argument.

But even if you've been convinced of all of the scientific evidence and the logical chains that eating Paleo is the healthiest way to live your life, diet is such an integral part of our lifestyle that the prospect of changing a diet regimen is daunting. It makes meals with friends or family complicated, having to explain what must seem to them as peculiar. It makes eating out require more haggling, asking waitstaff to substitute this for that ("what do you mean you want a burger without the bun?). And it means having to plan your meals with a little more foresight and intention.

Having eaten mostly consistent with the Paleo diet for six months and having eaten strictly Paleo for the last five weeks, I can say without hesitation that in my life it has been worth it. I feel better. My body aches less. I sleep better. I don't have energy ups and downs throughout the day, and my mental acuity is consistently sharp. Previously annoying medical issues like alopecia, eczema, and hypoglycemia have basically gone away. My body has gotten leaner and more muscular. It's really the best diet I've ever been on.

But even with all of the anecdotal examples, scientific studies, and persuasive argument, you may still not be ready to change your lifestyle. Don't worry - you can still take something away from all of this.

It's pretty mindboggling just how resilient the human body is. We can do some pretty rough things to our muscles, our skin, our digestive system, and our brains, and somehow, most of the time, our bodies manage to bounce back. Eating grains, dairy, and sugar isn't going to kill you like drinking drain cleaner or liquid nitrogen would kill you (unless you're diabetic, celiac, or afflicted with some other rare condition). What it will likely do, and the extent to which will vary based on the extent of their presence in your diet and variations in individual biology, is make you ill more often, make your mind and body operate less optimally, put you at risk for some pretty unpleasant diseases, and generally degrade your health and quality of life.

It's also not an all-or-nothing game. You can make incremental improvements in your diet and still see massive improvements in your body's function. Maybe for breakfast you skip the orange juice, the sugary coffee drink, the bowl of cereal, or the pancakes - instead you have a pork chop, some eggs, and a cup of coffee with coconut milk. Maybe you pack a lunch of a broccoli crown drizzled in olive oil with some leftover chicken from dinner last night instead of going out for fried rice or pizza downtown. You could even just shift dinner -- instead of accompanying every plate with white rice, potatoes, pasta, or a dinner roll, just double up on the vegetables.

You can also make incremental improvements by giving up certain things that really are some of the worst offenders. Coca-cola and other sugary drinks are an obvious place to start - maybe vow to give those up. Cook and make salads using healthful oils like olive, coconut, and avocado oil. Scratch shortening and foods deep fried in shortening from your diet (basically anything deep fried at a restaurant is fried in shortening unless they say otherwise). Do a little research to find local farms and ranches that sell meats from animals free to graze for their naturally preferred diets.

Incremental changes like this are great steps toward lowering the glycemic load in your diet and improving the fat composition in your foods. It will reduce the anti-nutrients doing damage to your digestive tract; it will increase your intake of vitamins, minerals, and anti-oxidants; it will help you feel full and avoid energy crashes during the day; and it will help you lose weight and avoid cardiovascular disease.

One extremely simple thing you can do, even if you change nothing else, that would have noticeable benefits in your body's overall health is supplement your diet with a good, quality fish oil rich in EPA and DHA omega-3 fatty acids. I recommend Carlson specifically because it doesn't taste like you're spooning down fish oil, it doesn't skimp on EPA and DHA by using a lot of ALA the way other fish oils do, and if you keep the liquid in the fridge, it stays fresh and potent. A week after I added it to my diet, I noticed my joints became far less inflamed after intense workouts and I started sleeping better. Consult a fish oil calculator to figure out how much of your fish oil to be taking.

Now that I'm off the 100% strict Paleo Challenge, I don't keep perfectly strict Paleo anymore. I've had a couple beers and a glass of wine. I knew the ketchup at Bob and Edith's was probably some generic ketchup chock full of corn syrup, but I had some anyway. But for the most part, a lot of the changes have stuck - and having gone through the challenge I'm at a baseline where I can notice stark differences in the way my body functions when I stray a bit from the diet. From there I can make decisions about the trade-offs between the diet and things that make me happy (like bourbon whiskey) even if they aren't Paleo.

But What If I'm Vegan/Vegetarian?

It probably deserves mention that I was vegetarian for 5 years. When I was in college and eating in the dining halls, my food options were limited to what they served me, and there was nothing ethical, natural, or humane about the meats they served. I like to think I'm a conscientious being, and I was uncomfortable eating meats from animals that I knew lived horrific and uncomfortable lives only to be faced with an undignified and gruesome death with zero respect paid in the process for the sacrifice it offered so that my life might be sustained. At the time and at my pay grade, there was no viable option for meats from animals who lived a humane life and faced a dignified death. So I cut out meat entirely. The market has changed now, and I have ready access to meats that are raised with dignity and respect. I'm comfortable eating meat knowing their sacrifice is honored.

If you're vegan or vegetarian because you believe it's healthier for you than the Paleo diet, I respectfully disagree both from my own experience and from my research. In comparing veganism and vegetarianism versus the standard American diet, there are clear and definite benefits to reduced consumption of palmitate and increased consumption of fruits and vegetables, but in the typical vegetarian or vegan diet, where meats once stood, grains and legumes take their place. Vegan and vegetarian diets are very rich in gluten, lectin, and phytates as well as carrying a higher glycemic load. Vegans and vegetarians are at higher risk for diabetes and hypoglycemia, for vitamin and mineral deficiencies, and for autoimmune disorders. It's simply not the diet we evolved to eat.

That being said, if you're a vegan or vegetarian because you believe it's unethical for humans to find food sources from animal products, humanely raised or otherwise, we ought to have a different conversation. I'm in no position to disagree with your ethics. They are your own, and you should follow your heart and intuition in deciding what's right and wrong. Your adherence to that ethical standard means you put yourself at greater risk for personal health complications and diminished quality of life in order that animals will not be raised and slaughtered in your name. Whether that trade-off is worth it is up to you.

I still encourage you to apply some of the nutritional science I've shared with you toward your dietary choices. A lot of manufactured vegetarian and vegan foods rely upon the worst qualities in grains, particularly wheat gluten and hydrolyzed vegetable protein. If you look at the ingredients, for example, on Morningstar Farms breakfast sausage patties, you find wheat gluten and hydrolyzed soy protein as the top ingredients. You should do your best to avoid these ingredients. Don't compensate for the absence of meat or other animal products in your diet by loading up on grains and carbs - instead, load up on vegetables and healthful oils. For vegans, clearly fish oil is off the table, but you still can get your necessary long chain omega-3 fatty acids from sea algae - remember that flax seed only contains ALA, not EPA or DHA.

Questions

I'm always learning more about this diet, and there's always more to learn. I encourage you to please share this series with your friends and family, particularly if you're eating Paleo and need a good resource to share your journey with the people you love. If you have any questions or if I can be of any assistance in helping you decide what's the best way to incorporate this knowledge into your own diet, please don't hesitate to send me an email. I'd be happy to continue writing on this topic.