There are so many reasons to pat yourself on the back after getting in a workout, from building strength to doing your mental health a solid. But while many people think of exercise as a great way to burn calories, a growing body of research suggests it’s not as effective on that front as you’d think.
The latest is a scientific analysis published in the journal Current Biology. It breaks down all the research on exercise’s impact on your calorie burn, as well as the way your body works hard to conserve energy. “We’re an evolved species. Our bodies are built to be clever and adaptable to try to keep the energy we burn every day within a narrow range,” Herman Pontzer, PhD, lead study author, professor of evolutionary anthropology and global health at the Duke Global Health Institute and author of Adaptable: The Surprising Science of Human Diversity, tells SELF.
Dr. Pontzer’s research breaks down the unique and interesting ways your body tries to conserve energy, even when you’re racking up the miles. Here’s the deal.
The study dives into just how hard your body is working to keep you at a baseline.
For the review, Dr. Pontzer and his colleague Eric Trexler analyzed 14 studies featuring 450 people that analyzed energy burn and exercise. They found that when you burn calories through exercising, your body finds a way to save those calories elsewhere.
While you might see a bigger calorie burn when you first start a new workout routine, your body notes that change in your lifestyle and responds. That can include doing things like burning less calories than usual when you’re sleeping at night, encouraging you to take it easy the rest of the day after a hard workout, or ramping up your hunger cues so you eat more, he explains.
“If you only have exercise by itself—no change in diet—then you cancel out about 50% of the exercise calories that you burn,” he says. “Unfortunately for weight loss, if you don’t control your diet, you will eat the other 50%, so there will be no imbalance between calories eaten and calories burned, resulting in little or no weight loss.” But if you pair your exercise with dietary changes, the lower calories you take in may lead to weight loss, “as long as calories eaten are less than calories burned,” Dr. Pontzer says. Even then, it’s really your diet that’s leading to the weight loss, not the exercise you do.