Why Exercising May Not Help You Lose Weight

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AAnyone who has ever tried to lose weight by increasing their workout regimen can tell you it’s a struggle. But why? If you keep the same diet and use the treadmill to burn an extra 500 calories a day, you should start losing weight. It’s just math, right?

This traditional model, called the additive model, measures your total energy expenditure as the sum of the amount of energy you expend exercising and the amount of energy your body expends performing daily tasks that keep you alive, such as cellular repair.

But a newer model, called the constrained model, takes a different approach. Instead of adding the extra energy spent on exercise to the total, the constrained model says your body has a more limited amount of energy it can burn each day. In this model, your body compensates by spending less energy on the tasks that keep you alive after exercise.

Read more: “Running is always blind”

So which model is the right one?

To investigate, researchers at Duke University analyzed data from 14 different studies involving 450 people who participated in exercise programs, publishing their results in Current biology. By comparing the energy participants were supposed to burn with the amount of energy they actually burned, they were able to get a rough estimate of the compensation our bodies make for exercise.

They found that on average, only 72 percent of calories burned during exercise add to the total daily expenditure, with the remaining 28 percent being compensated by our bodies.

However, the researchers pointed out that while there was no increase in calories burned, exercise still led to an overall increase in total calories burned. Additionally, the 28 percent pay figure is just an average; some organizations can compensate more and others less.

In other words, don’t cancel your gym membership just yet.

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Main image: Michal Sanca / Shutterstock

• Jake Currie

  Published on February 11, 2026

  Jake Currie is a writer based in Brooklyn, New York.