Your Diet is Bad and You Should Feel Bad!

This new and exciting series provides systematic deconstruction of popular diets.

Episode 1: Paleo

Theory: Diseases of affluence are manifested by a diet high in starch, dairy, oil, and salt. Early humans did not consume these products in large quantities, nor do modern-day hunter gatherer tribes, and both populations have/had lower rates of obesity and its co-morbid conditions. It follows that modern humans seeking to improve their health should emulate the [presumed] eating habits of early humans. Sounds like a plan.

False Premises:

1. Evolution has not resulted in substantial changes in the last 20,000 years. Practitioners of paleo dieting insist that we are near biologically identical to our ancestors who inhabited the African Savannah. This contrasts very strongly with actual science, as we are extremely adaptive, even within our own lifetimes. Gene transcription is readily altered with the slightest change in environment, stress, nutrition, or medicine. This is why we all have hundreds of benign cancers in our bodies. Semi-permanent modifications can happen within only a few generations. The vast differences in lactose tolerance among European nations is indicative of how easily we adapt.

2.  Diseases of affluence are a product of agriculture-based diets, rather than by-products of advances in transportation and technology. Most of our ancestors were farming by 2000 BC (before cruci-fiction), some had been since 8000 BC or earlier. The modern obesity epidemic began circa 1970. Throughout the 1950's, there were more reported cases of underweight than overweight children (in America, land of plenty). The 80% grain diet of most peasants for most of history did not result in diabetes, high blood pressure, or obesity, even during times of immense surplus. They no doubt lived short, brutish lives, in constant fear of drought, flood, predators, and landowners, and crippled by the cumbersome nature of their work, but they suffered no diseases of affluence. Even the upper classes, who had access to honey, cheese, olives, salt, and aluminium-tainted white bread, were pathetically frail by modern standards. What they did not have was partially hydrogenated oil, high fructose corn syrup, and 2am delivery service.

3. Paleo dieting was causal, rather than coincidental. There is evidence of a disparity of health between western nations and hunter-gatherer tribes. There is no evidence that a paleolithic diet contributes to the disparity anymore than the absence of footwear, or free hanging breasts. Of course, there are a great many extremely dangerous and unnecessary additives in our food which contribute to our poor health, but our reduced well-being has no bearing on the efficacy of other people's diets. If American life expectancy is shorter than that of any given indigenous population, it is because we lowered ours, not because they raised theirs. Good health and longevity are seen in many diverse populations, all with unique diets and lifestyles. Typical Japanese and Mediterranean cuisine are both high-fat and high-starch, yet both of those populations have superior life expectancy. The only common link of poor health across the world is excessive food processing, toxic by-products (fats and proteins denature and sometimes produce volatile compounds), and a penchant for inactivity. The perceived fitness of tribal populations has a lot more to do with their energy expenditure than their lack of bread.

4. Natural occurrence is linked to natural availability. The paleo diet is founded on a template of elimination, rather than inclusion, that is, it has some cohesive theory about what should not be consumed, but has very little to say on what should be consumed, and why. All wild game and fish are allowed, but how do we verify that our ancestors had access to them? If our ancestors were fishermen for thousands of years, should we consume terrestrial animals? All non-starchy vegetables are allowed, but certainly, the creators of this diet know that before global oceanic trade routes were established, certain vegetation was only available in certain regions. How can I be sure that as an Italian, I can safely and efficiently extract nutrients from a tomato, when that crop is native to Peru? Populations unaccustomed to certain crops may develop food allergies or intolerances, or they may lack sufficient amounts of certain digestive enzymes. If we are to assume that all food is of equal value to all populations, then we may as well claim that there are no variations in human DNA. Do you need to eat beets and liver so your blood cells don't disintegrate? I do.

5. Grain consumption was relatively unknown prior to organized farming. This is a really interesting one, because paleo advocates like to claim that "before" we became farmers, grains were not a significant part of our diets. Surely, however, they must be aware that the variety and abundance of wild grains was far greater in the paleolithic era than it was after the advent of agriculture. Organized farming, especially in advanced societies with barter and trade, is geared towards specialization and yield efficiency. Crops are selectively bred to produce the most marketable products. Far from avoiding gluten, our ancestors were likely exposed to more varieties of wheat in one season than we will ever experience in our lives. If anything, we have become less versatile in digestive capacity, as we no longer have the vestigial structures (functioning appendix, wisdom teeth) of our plant-sampling forebears.

6. Grains are loaded with antinutrients. The compounds of concern are phytic acid (actually far more prevalent in nuts, which are paleo approved), which chelates minerals, and trypsin inhibitors, which prevent hydrolysis of proteins into peptides small enough to be transported into the bloodstream. That paleo dieters have any legitimate concern for mineral balance is absurd, given that any diet based on the paleo model is almost certainly calcium deficient. Further, trypsin inhibitors are only found in substantial quantity in a few legumes (soy, most notably), and their inhibitory effects are transient and quantitatively linked (X mol of trypsin inhibitor can bind X mol of trypsin during a single feeding). The role of antinutrients is insignificant, especially when one considers the benefits of nutrient and energy dense whole grains. Oddly enough, modern-day processed and refined flour is completely bereft of antinutrients, yet is somehow still linked to diseases of affluence. Might have been something other than a 3% reduction in serum zinc that caused you to get diabetes.

A Poor Choice for Athletes

Just because paleo is based on half-truths and faulty reasoning doesn't mean it's ineffective. On the contrary, there are plenty of other reasons why it should be avoided by a person involved in sport.

1. Glucose is the body's preferred fuel source. What this means is not that the body "likes" glucose, but that it can produce the most energy most efficiently from glucose. Other substrates are less efficient, and are used secondarily. In very low intensity aerobic work, glucose demand is fairly low, in most other life activities, glucose demand (that is, stress placed upon the glycolytic energy system) is moderate to high. Engaging in high intensity activity while glycogen depleted is perfectly feasible, but fatty acid oxidation does not provide energy at a sufficient rate, so the body must find other ways to compensate. Possible routes of compensation include destruction of tissues to form ketone bodies, and deamination of proteins to form glucose. Using protein as a fuel source is inefficient (still can't match rate of normal glycolysis), expensive (carbohydrates are comparatively cheap and plentiful), and dangerous (kidneys not equipped to handle mass protein breakdown). Fortunately, you're more likely to push ketosis into ketoacidosis before you're able to strip off enough muscle to shut down your kidneys. Of course, ketoacidosis can simply dehydrate you into a Terry Schiavo coma, so it's a win-win, regardless of which system fails first.

2.  High protein intake increases calcium excretion. This is more than offset by a typical athlete's diet, which contains ample sources of easily absorbed calcium, but not so with a paleo diet. Calcium is required for muscle contraction, variations of which comprise every athletic movement in existence. Mineral imbalances cause cramps, weakness, fatigue, soreness, and impairment of coordination (firing of motor units).

Why You Think It Works, and Why You are Wrong  

1. Immediate and visible weight loss. After a week of paleo dieting you may be "down 6 pounds" and you may "look thinner", but it's very unlikely that your fat mass changed during that time. The starch-free diet results in depletion of glycogen stores. Each glycogen molecule holds three times its weight in water, so your (approximately) one pound of muscle glycogen is holding three pounds of intramuscular water. Protein breakdown and ketosis both have a diuretic effect, the former through production of nitrogen waste, the latter through disruption of mineral balance. The accumulation of waste products, along with the absence of antidiuretic hormones (on account of sodium and potassium loss) causes increased urination. Because fat is anhydrous, and muscle tissue is hydrated by glycogen, the reactions for their breakdown require external water. A drop in subcutaneous water gives the illusion of fat loss, but it's just water loss brought about by a shift in osmolarity.  

2. You are less hungry. You actually aren't. Malnutrition often operates independently of perceived hunger. When you are "hungry", it usually means something has stimulated insulin release, causing you to desire food, regardless of your body's actual requirements. Starving people have a very weak insulin response, and generally experience more pain and fatigue than what we recognize as "hunger". It's a biological adaptation for survival in times of scarcity. If we became ever increasingly hungry in the absence of food, we'd have no clarity of mind, and no way to actually obtain food. After a while, your insulin response becomes weaker, your appetite becomes suppressed, and your metabolism slows. This doesn't mean the diet is "working", it means your body recognizes a state of deficiency, and is adjusting accordingly.

3. It's not sustainable. It has precious little to do with willpower, resolve, or discipline. While your body is given no cue that food is available, it will remain, for the most part, in the aforementioned starving mode. Any stimulus, however, that would have it discern that starvation is not its necessary fate, will send all of the hunger signaling systems into overdrive. This is simple survival instinct. If you go days without food, and stumble into an apple orchard, you'll experience extreme sensitivity towards, smells, sights, and sounds. Every gram of sugar will be cloyingly sweet and infinitely delicious, because your body only understands ensuring its survival. All restricted carbohydrate diets cause extreme rebound hunger upon reintroduction of balanced nourishment. It's much easier to starve to death in nature than in civilization. One teaspoon of oatmeal or crumb of bread will drive a deprived person into a murderous rage. The hypersensitive ravenous state remains active well after all of the lost calories have been accounted for, which is why crash dieters tend to weigh more after relapse than they did before the initial attempt.