In addition to the poor Western diet, the modern sedentary lifestyle is looked upon as a major contributor to the obesity epidemic. Yet an intriguing study of a primitive Tanzanian tribe found that these hunter-gatherers burned about the same number of calories as the average office worker. The researchers conclude that even the most active person is likely to gain weight if they don’t eat right.
Diet vs. exercise for losing weight
Exactly why westerners are getting so fat can be as simple as taking in more calories than are burned. But are you going to gain weight by eating too much, or exercising too little? Given our technology-driven modern society, it’s assumed that we get fat because we burn far fewer calories than our hunter-gatherer ancestors. But a study led by Herman Pontzer of Hunter College in New York, the first ever to measure calorie burning in hunter-gatherers, suggest this assumption is wrong.
Technology and tribespeople
In an article published in the journal PLoS ONE, Pontzer explains the ingenious way his team tracked energy consumption of the Hadza tribe in northern Tanzania. Hadza volunteers were fitted with GPS units to track how many miles they covered each day hunting and gathering food. They also drank “doubly labeled” water, a solution created by replacing normal hydrogen and oxygen molecules with modified tracer molecules.
After 11 days, the researchers studied the tracers in the Hazda’s urine to determine energy expenditure and metabolic rate, combined with the data on how much ground they covered. A comparison of the Hazda data with similar measures for the average Westerner was surprising.
Parallel metabolic rates
The Hazda demonstrated far more physical activity than the average Westerner. The men walked about seven miles a day and the women about three. Strangely enough, however, they didn’t burn more calories. In fact, their average metabolic rate was about the same.
The study suggests that across populations and lifestyles, the human body compensates to keep metabolic rate fairly constant. “The vast majority of what we spend our calories on is things you will never see like keeping our organs and immune system going,” Pontzer said. “If you spend a bit more [energy] on something like physical activity, you spend a bit less on something else but you do not notice it. This study shows that you can have a very different lifestyle, but [energy use] all adds up tot he same level no matter what.”
Don’t discount exercise
The amount of calories we burn today compared with our hunter-gatherer ancestors apparently hasn’t’ changed. But over the last 50 years, the amount of calories we’re eating has risen dramatically—simple as that.
Simply exercising more probably won’t protect you from gaining weight. And millions of dieters understand that to lose weight, it’s more effective to cut calories than exercise more. But the Hazda study also suggests that exercise is essential for staying healthy.
The Hazda spent a greater percentage of their energy expenditure on physical activity than the average Westerner, even though the total calories burned was similar. This tendency could explain why the tribal elders manage to avoid chronic age-related diseases that plague Westerners such as heart disease, stroke and diabetes.
Cut calories to lose weight. Exercise to stay healthy.