Top Ten Problems With Applying The Paleolithic Diet Principles: Number 10

When I wrote The Garden of Eating (hereafter GOE), I still had not totally gotten past all the false beliefs I held about dietary fats and the benefits of eating lots of fruits and vegetables. Since publishing The Garden of Eating, I have continued to learn and refine my understanding and practice of Paleolithic diet, and along the way I have discovered a number of ill-founded mistakes I made and that I think others make in applying paleo diet principles to modern life. Rectification of these errors in my own practice have resulted in improvements in my health and body composition. So, in the next 5 to 10 posts I will report and explain the most important errors that create problems for would-be paleodieters, and how to correct them.

10. Eating on an agricultural schedule

In the GOE, we laid out meal plans that suggested three to four meals daily. Like many people, at the time I still believed that research had shown that people need to eat every four to five hours to prevent a decline in metabolism, stabilize blood sugar, and maintain a supply of amino acids to prevent loss of lean mass. Since then, I have learned otherwise. We have no scientific support for frequent eating, especially not in the context of a Paleolithic diet.

When I attempted to eat palediet four meals daily, I frequently found that I simply did not have an appropriate hunger for each meal. Also, I intermittently had bouts with indigestion, abdominal bloating, and constipation triggered by eating foods rich in fat. At times, I literally felt fed up with eating protein and fat, and would gravitate toward eating more tubers and fruits.

So I started questioning. My experience suggested that either people aren’t physiologically adapted to eat a diet high in fat and protein, or that my application of paleodiet principles contained some error. Ethnographic, archaeological, anatomical, and clinical trial evidence all ruled out the former alternative, so I figured the problem lay in my application of the diet.

What did I do wrong? Recent hunter gatherers typically consumed only one or two main meals in a day, often after spending a morning and early afternoon hunting or gathering mostly on an empty stomach. At these meals, H-Gs ate large amounts of animal protein and fat. The human gut has several characteristics indicating adaptation to intermittent feeding on high caloric density foods:

1. A relatively small stomach (only about 20 percent of total gut volume) despite large energy requirements, indicating adaptation to consuming high energy density, i.e., high fat foods.
2. Most (about 65 percent) of gut volume in the small intestine, a characteristic which seems more appropriate for prolonged inter-meal digestion and absorption periods than for frequent feeding.
3. A well-developed gall bladder, which stores bile for intermittent use on demand to emulsify fats for enzymatic digestion, and which only empties efficiently with large doses of dietary fat (See Barry Groves’s good discussion of how low-fat diets cause gallstone formation).

Three meals or more in a day developed only after the rise of agriculture and the adoption of high carbohydrate diets. A constant high meal frequency requires constant presence of stored food, which requires either non-perishable staple foods like grains or a ready refrigerator, neither available to hunter-gatherers.

If you eat a low-fat, high-carbohydrate diet, you will very likely be driven to eat frequently by the insulin response to the high-carbohydrate intake, which locks up your fat stores and drives down your blood sugar, putting you in the constant pincer grip of hunger. Frequent eating and its attendant fluctuations in blood sugar and insulin surges also promote daytime fatigue as energy goes into digestion, activating the parasympathetic—rest and digest—nervous system.

However, if you eat a paleodiet based largely on fat and protein, eating too frequently will not give your liver adequate time to produce sufficient bile for smooth digestion of fats, and you may get the kinds of digestive problems I mentioned above, along with the impression that you don’t or can’t tolerate a high fat diet. It could cause you to question or abandon paleodiet.

Of interest here, eating too frequently could also promote colon cancer by prolonging the colon’s exposure to bile acids. Wei et al did a case-control study (correlation, not causation) found a 50% lower risk of colon cancer among men, but not women, eating fewer than three meals daily. This weakly supports the hypothesis that humans are adapted to eating fewer than 3 meals daily.

Further, if you eat animal protein in Paleolithic quantities, this will by nature reduce your appetite for many hours, which signals that your body is not ready to eat. During this period your liver works intensively converting amino acids to glucose. Naturally, this would tend to reduce your appetite for animal protein.

Finally, a reduced carbohydrate intake reduces your insulin level, and this allows the body to mobilize fat stores so that you can go longer between meals. In other word, if eating paleo, you will have a low normal blood sugar level (due to low carbohydrate intake) and you will run on fat, not sugar, so you won’t have eat to “stabilize your blood sugar.”

We have no evidence that anyone must eat every few hours to avoid a depression of metabolic rate. Studies of fasting have shown that people can go at least 72 hours without food with no decline in metabolic rate, and no loss of lean tissue, and, once the fat starts flowing, no loss of energy. Webber and McDonald even found an increase in metabolic rate after 36 hours of fasting [Br J Nutr. 1994 Mar;71(3):437-47].

We also have no evidence for the claim that you must eat protein several times daily to prevent loss of muscle, or promote gain of muscle. In fact, Stote et al showed that when people ate all their daily caloric requirement in one meal (in a four hour period) daily for eight weeks, they gained muscle and lost fat, whereas when they ate the standard three meals daily they did not experience this body recomposition. The infrequent feeding regimen also reduced cortisol levels, suggesting a reduction in physiological stress.

During a 24 hour fast GH output increases markedly; the frequency of GH pulses increases by 25%, the peak amplitude of GH pulses doubles, and the interpeak serum GH levels quadruple [read this and this]. A study by Norrelund et al indicates that the protein-retaining effects of GH inhibit muscle-protein breakdown during fasting. Fasting-induced increases in GH may therefore account for the increase of lean mass found in the Stote et al study mentioned above.

Since the release of GOE, I have reduced my own meal frequency to not more than thrice daily, most usually eating only twice daily, with both meals consumed in a 6-8 hour window, so that I now fast 16-18 hours daily. This has improved my digestion and elimination, my energy level, my mood, and my body composition (less fat, more muscle). My next book will explain how to adopt this intermittent fasting schedule in a systematic fashion.

Stay tuned for the next installment, we have nine to go.