What Constitutes the Best Diet for Humans?
A study of modern hunter-gatherer groups found that they exhibit generally excellent metabolic health while consuming a wide range of diets.
Nutrition experts have long debated whether there is an optimal diet that humans have evolved to eat. A study published in December 2018 adds a twist to this discussion, finding that there is no single natural diet that is best for human health. The research, published in the journal “Obesity Reviews,” examined the diets, habits, and activity levels of hundreds of modern hunter-gatherer groups and small-scale societies, whose lifestyles are similar to those of ancient populations.
The study discovered that all these groups generally exhibit excellent metabolic health while consuming a wide range of diets. Some get up to 80 percent of their calories from carbohydrates, while others primarily eat meat. However, there are some common aspects: almost all eat a mix of meat, fish, and plants, consuming foods that are generally rich in nutrients.
In general, they consume much more fiber than the average American. Most of the carbohydrates come from vegetables and starchy plants with a low glycemic index, meaning they do not lead to rapid spikes in blood sugar. It is not uncommon for hunter-gatherers to eat sugar, which they mainly consume in the form of honey.
The findings suggest that there is no “true” diet for humans, which “can be very healthy across a wide range of diets,” said lead author Herman Pontzer, an associate professor of evolutionary anthropology at Duke University.
“We know this because we see a wide range of diets in these very healthy populations.”
One thing hunter-gatherer populations have in common is a very high level of physical activity. Many walk between five miles (8 km) and ten miles (16 km) a day.
Yet, paradoxically, they do not have higher levels of energy expenditure than the average American worker.
This suggests that health officials should consider recommending exercise as a way to improve metabolic health, but not necessarily as an antidote to obesity by burning calories.
From a public health perspective, modern hunter-gatherers are characterized by a relative lack of chronic diseases such as heart disease, hypertension, and cancer. Obesity rates are low. They have very high levels of cardiorespiratory fitness, even at an advanced age. And type 2 diabetes and metabolic dysfunction are almost never seen.
Life in hunter-gatherer societies, however, is not easy. Infant mortality rates are high due to infectious diseases. Deaths from accidents, gastrointestinal diseases, and acute infections are common. But those who survive to adulthood often reach old age relatively free of the degenerative diseases that are the norm in industrialized nations. They are typically fit and active until the end, suggesting that there is something about their lifestyles that allows them to age healthily.
“Few of us would want to trade places with them. Their lives are still hard,” Dr. Pontzer said. “But the things they get sick from are things we know how to deal with, and the things they don’t get sick from are things we struggle to deal with.”
It’s possible that genetics and other non-lifestyle factors protect them from chronic diseases. But studies show that when people born into hunter-gatherer societies move to big cities and adopt Western lifestyles, they develop high rates of obesity and metabolic diseases just like everyone else.
Michael Gurven, an anthropologist at the University of California, Santa Barbara, has conducted extensive research on the Tsimane, a Bolivian people who live a subsistence lifestyle of hunting, gathering, fishing, and farming.
The Tsimane get most of their calories from complex, high-fiber carbohydrates like plantains, corn, cassava, rice, and bananas, supplemented with game and fish.
Dr. Gurven has published detailed studies showing that they have exceptional cardiovascular health and almost no diabetes. Yet Dr. Gurven has seen several cases of Tsimane people developing and dying from type 2 diabetes after leaving their villages and moving to the nearby town of San Borja, where they took sedentary jobs and abandoned their traditional diet.
“They went from their traditional diet to eating in the city where everything is fried,” he said. “They started eating fried chicken and rice and drinking Coke. Some of these people can see a pretty rapid change in health.”
Insights from Dr. Pontzer’s New Study on Hunter-Gatherer Diets
For the new study, Dr. Pontzer and his colleagues analyzed data on hunter-gatherers and other small-scale societies around the world, from South America to Africa and Australia. They examined detailed dietary assessments from the fossil and archaeological records to understand what early humans ate. Additionally, they included new data collected from the Hadza, a community of people who spend their days hunting and foraging in northern Tanzania, just as their ancestors have for tens of thousands of years.
The Hadza eat what some call “the oldest diet.” Dr. Pontzer has spent time with them and studied their health extensively. On a typical day, the Hadza set out early in the morning to hunt and forage on the savannah. Women traverse hilly terrain to gather wild berries and dig for tubers that resemble fibrous sweet potatoes. These tubers aren’t easy to come by, as women use sticks to dig them out, sometimes while carrying babies on their backs. Men go out to hunt animals, often killing small ones, but about once a month, they manage to kill something as big as a zebra, warthog, or gazelle.
On days when their hunts fail, they head to beehives to collect honey, which is a favorite food, accounting for at least 15 percent of the calories in their diet. “On any given day in a Hadza camp, there’s almost always honey, some meat, and tubers,” Dr. Pontzer said.
The Hadza consume similar amounts of calories per day to the average American. However, they rely on a fairly small number of foods and specifically avoid ultra-processed foods like chips, candy bars, and ice cream, which combine large amounts of fat and simple carbohydrates — foods designed to be irresistible even when we’re not hungry.
The lack of novelty and variety in hunter-gatherer diets may be part of the reason they don’t overeat and become obese. Studies show that the more variety of food choices we have, the longer it takes to feel full, a phenomenon known as sensory-specific satiety. “It’s the reason you always have room for dessert at a restaurant even when you’re full,” Dr. Pontzer said. “Even if you’ve had a savory meal and can’t eat another bite of steak, you’re still interested in cheesecake because it’s sweet, and that button hasn’t gone out of your brain yet.”
I hope that this article from the prestigious American newspaper and from official science itself can be the first step towards the progressive destruction of the dogmas of the Mediterranean diet and lead people to eat again like our ancestors.