A new study has found that being physically active really does make you burn more calories overall—without your body cutting back energy use elsewhere.
The research, published in Proceedings of the National Academy of Sciences and led by scientists from Virginia Tech, the University of Aberdeen, and Shenzhen University, challenges the idea that the body “balances out” energy use when we move more.
For years, scientists have debated how our bodies manage energy.
Some believed the body has a fixed “energy budget,” similar to a set salary: if you spend more energy on physical activity, the body compensates by reducing energy spent on other functions, such as digestion or immunity.
Others thought the system was flexible, more like earning extra commission—the more you move, the more energy you use overall.
To test these ideas, the researchers measured the total daily energy expenditure—the total number of calories burned in a day—in people with different activity levels, ranging from those who were mostly sedentary to ultra-endurance runners.
The 75 participants, aged 19 to 63, wore sensors on their waists to measure movement and drank small doses of water labeled with special isotopes of oxygen and hydrogen.
By tracking how these isotopes left the body through urine, researchers could calculate how much carbon dioxide was produced and, therefore, how much energy was used.
The results were clear: people who moved more burned more energy overall, and their bodies didn’t seem to “save” energy elsewhere to make up for it.
“We found that more physical activity is linked to higher calorie burn, no matter a person’s body composition,” said Kevin Davy, a professor at Virginia Tech and one of the study’s authors.
“The body doesn’t seem to compensate by cutting back energy use for basic functions.”
In other words, when your body uses energy for basic tasks like breathing, circulating blood, and regulating body temperature, it keeps doing those things at the same rate—even if you exercise more. That means the extra calories burned during physical activity directly increase your total daily energy use.
The study also found that people who were more active tended to spend less time sitting still, which further contributes to better overall health.
According to the researchers, this finding reinforces the idea that moving more—whether through walking, exercise, or simply staying on your feet—genuinely increases energy use and helps maintain a healthier lifestyle.
Lead author Kristen Howard noted that their study focused on people who were adequately fueled, meaning they ate enough to support their activity.
She suggested that cases where the body seems to “conserve” energy might happen when people are not eating enough.
The researchers say more studies are needed to explore when and in whom the body might adjust its energy spending. But for now, the message is clear: every step, stretch, and workout truly adds to your daily calorie burn—and your body doesn’t cheat you out of it.
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