Sedentary and physically active people can burn almost the same amount of energy per day, shows a new American study. The researchers therefore argue that the fight against obesity must focus more on diet – and less on exercise.

In the study, published in the scientific journal PNAS, researchers compared data from 4,200 people from different continents with different lifestyles – including herding cultures in Siberia, hunter-gatherers in Tanzania, as well as people from both low-income and high-income countries. In total, they compared 34 different population groups.

The results show that total daily energy expenditure did not differ significantly between the different population groups. This means that, for example, a hunter-gatherer used the same amount of energy as an office worker in Sweden during a day.

— Even when people live different lifestyles, once we account for the effects of body size, we do not see meaningful differences in the total number of calories people burn, says Amanda McGrosky at Elon University in the US, who is the lead author of the study, in a press release.

McGrosky points out that obesity is therefore primarily about increased calorie consumption, not decreased activity expenditure.

— If you are worried about excess body fat, focus on calories in, not calories out, the researcher suggests.

Westerners eat too much

Obesity and overweight are growing health problems in the Western world, something often linked to the increasingly sedentary culture. However, this study suggests that sedentary behavior is not the biggest problem causing obesity, and McGrosky believes the study offers hope in the fight against obesity. Instead, one should look at diet and especially reduce the intake of ultra-processed foods and increase the proportion of healthy ones.

The researchers therefore suggest that it is not sedentary behavior that is the culprit in Western countries’ obesity epidemic, but rather that people simply eat too much and too unhealthily.

Exercise is still important

However, the researchers point out that this does not mean one should exclude exercise and movement, as it has a range of health-promoting benefits such as reduced risk of cardiovascular disease, premature death, and also improves mental health.

— A key takeaway from the study is that increases in body fat that accompany changes in lifestyle are primarily linked to changes in energy intake, or diet. Physical activity is still very important for all-around health and should be considered complementary to diet, says McGrosky.