If you are part of the HumanaNatura community, you aspire to optimal levels of health and vitality, in part through the use of health practices derived from evolutionary science.

The diet we eat in our community is comprised of the foods that humans are designed by nature to consume, the exercises we engage in mimic the activity patterns of our natural ancestors, and we strive to achieve and maintain naturally healthy personal and social lifestyles. The topic that I want to cover in this article is related to natural nutrition and diet, focusing on optimal meal frequency.

When viewing meal frequency from an evolutionary perspective, we are inclined to conclude that humans were not evolved to consume food continually, or even frequently.  In nature, before the advent of farming, there was of course no guarantee that food would be available or when it would be available. It is probable that natural humans, who lived nomadically and used mobility to help ensure food availability, would have been subjected to many hours or even days without food throughout much of our natural history.

It is also likely that when food did become available, for example after a protracted but successful hunt or catch, our ancestors would have consumed a large quantity of calories – to make up for the effort of hunting and concurrent gathering, to offset the calorie deficit since the last hunting success, and to build calorie stores until the next hunt. Once the products of hunting and gathering were eaten, a period of fasting would then have naturally ensued, either owing to a period of rest and/or with fresh movement in search of additional food.  This envisioned cycle of feasting and fasting, in fact, is quite probably the basic template of hunter-gatherer or natural human eating.

The idea that feast-fast eating is our natural pattern is consistent with the fact that many people find it difficult to exercise or remain active on a full stomach, while they are generally more alert and energetic when feelings of fullness pass. The question to better understand why this is the case is a simple one:  Why would hunter-gatherers pursue food at all? The answer to this question is obviously because they were hungry, or anticipated being hungry in the future.   It makes sense that hunter-gatherers would be most prone to activity (hunting and gathering) on an empty stomach, and least so when satiated.

It is therefore reasonable to hypothesize that the human body will perform better both mentally and physically in a moderately fasted state, simply due to the frequent requirement for performance at this time during our long, pre-civilized hunter-gatherer past (also known as our Paleolithic era). When a hunt was needed in nature, humans would have been required to be prepared, physically and mentally, in order to be successful. Humans who could not hunt and gather well in a fasted state, as they arose through random variation, would have been less likely to survive and pass their genes on to future generations.

This proposal that people are adapted to a feast-fast eating cycle may also help to explain why modern humans have such a pronounced tendency to be sedentary and lethargic across large parts of their day. Since the advent of agriculture at the end of our Paleolithic era, the availability of food has become more far more constant and increasingly reliable with our advancing technology. Rather than periodically hunting and gathering, and immediately eating this food amidst a nomadic lifestyle, people now are now apt to have an immediate and near constant supply of high calorie foods. The fact that modern people can and do eat whenever they please may reduce our natural urges for hunting, gathering, and socialization (for exercise and other activity) and thereby promote our more sedentary and less healthy modern lifestyle. It is my contention that if modern people were to adopt a more natural frequency to their meals, they would also increase their natural levels of activity, resulting in a simultaneous improvement in both diet and exercise.

With these ideas in mind, let us turn to our central question:  How often should we eat today to best mimic and benefit from the pattern of meal frequency we would be presented with in nature?  To be prudent, the answer to this question needs to be expressed as a range, since there was likely fairly high variation in food availability in different regions of the world and at different times of the year. For instance, hunter-gatherers living in Sub-Sahara Africa would normally have had a much larger variety of plant food sources that could be consumed between hunts, reducing the length and depth of their fasting periods.  Hunter-gatherers living in more extreme climates, however, were far more dependent on animal sources for their calories and would have been subjected to longer fasting periods between meals (due to the inability to snack on plant foods between hunts).

Loren Cordain, a leading researcher in Paleolithic nutrition, has concluded from studies done on modern day hunter-gatherers that the natural meal frequency for humans is one large feeding a day, normally consumed at or near night. This seems consistent with our discussion of natural human eating patterns.  It would make sense that hunter-gatherers would hunt during the day to maximize the chances of success, and then eat a large meal, later in the day, after a successful hunt. This eating pattern is also conducive to and probably part of natural human sleep patterns too. Meals tend to raise and then lower our blood sugar levels, causing us to feel tired and lethargic, encouraging nighttime sleep (or lethargy throughout the day in modern individuals who eat three large meals a day). This fact that meals tend to cause us to feel tired is suggestive that we ate infrequently, and often at or near nightfall when we were least required to be active.   

It is important to note that such feast-fast eating patterns have been found by researchers to decrease the occurrence of Syndrome X diseases (heart disease, diabetes, hypertension, stroke, etc.) and to increase life span in laboratory animals.  In recent studies, putting laboratory mice on day-on/day-off feeding cycles, researchers were able to increase their life spans by as much or more than mice placed simply on calorie-restricted diets (which have already been shown to be life-extending versus higher-calorie diets).

These studies have also reported a reduction in blood sugar and circulating insulin levels, as well as improvements in blood lipid profiles, all suggestive that intermittent eating and fasting may be an effective tool in the prevention and treatment of a variety of diseases of modern civilization. Other researchers utilizing intermittent fasting have noted improvements in known markers for chronic disease. Similar studies are also now in progress on squirrel monkeys, close biological cousins to humans.  So far, early indications are that similar beneficial health effects are likely through intermittent feeding and fasting.

Through reasoned ideas from evolutionary theory, observations of modern hunter-gatherer populations, and new and compelling evidence from scientific studies, it would be wise to consider a feast-fast meal pattern as part of a natural health lifestyle – and especially to reduce our frequency of large, calorie-rich meals.

Growing evidence suggests that one large evening meal per day is most appropriate and consistent with human evolutionary design, with fasting or light meals in between. The effects of this pattern of feast-fast eating are still being studied, but may offer significant health benefits while simultaneously promoting a more active daily lifestyle and better rest at night.

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Greg Battaglia is a member of the HumanaNatura community.

Sources:

Beneficial effects of intermittent fasting and caloric restriction on the cardiovascular and cerebrovascular systems.

Intermittent fasting dissociates beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from calorie intake. http://www.ncbi.nlm.nih.gov/entrez/query