EXERCISE: NOT A WEIGHT LOSS SOLUTION

 EXERCISE: NOT A WEIGHT LOSS SOLUTION

Just hitting the gym might not be enough to shed pounds. Research published in Current Biology helps explain why our bodies adapt to higher activity levels, meaning we don’t always burn more calories even when we exercise more.

The study’s authors argue that we need to reconsider how physical activity really affects our daily energy use. Their findings also underscore the importance of diet alongside exercise for anyone aiming to lose weight.

“Exercise is incredibly important for your health,” says Herman Pontzer of the City University of New York. “That’s the first thing I tell anyone who asks about these findings. There’s plenty of evidence showing exercise helps keep your body and mind healthy, and none of our work changes that. What we’re saying is, diet matters too—especially if you’re trying to manage your weight or reverse unhealthy weight gain.”

It’s common for people to lose weight initially when starting an exercise program, only to hit a plateau or even regain weight after a few months. Extensive studies have also found that people with very active lifestyles don’t burn dramatically more calories each day than those with sedentary routines.

Pontzer saw this firsthand while studying the Hadza, a hunter-gatherer group in northern Tanzania.

“They’re extremely active—walking long distances and doing lots of physical work each day,” he explains. “Yet, their daily calorie expenditure was about the same as people living much less active lives in the U.S. and Europe. That was a real shock, and it made me question how activity and energy use are connected.”

To dig deeper, Pontzer and his team measured the daily energy expenditure and activity levels of more than 300 men and women over the course of a week. Their data showed that while physical activity does have a measurable effect on energy expenditure, it’s pretty limited. The increase in calories burned was only significant among those who were less active. People with moderate activity levels burn about 200 more calories per day than the most sedentary individuals. But anyone more active than that didn’t see further increases—their bodies adjusted.

“The most active people used the same amount of energy each day as those who were just moderately active,” Pontzer says.

The takeaway: More exercise doesn’t always mean more calories burned. There may be a “sweet spot” for physical activity—too little is unhealthy, but beyond a certain point, your body adapts and limits extra calorie use.

Next, Pontzer’s team plans to study precisely how the body adapts to higher activity levels. They’ll look for changes in areas like immune function or the reproductive system to understand how the body manages greater physical demands without burning extra calories.