Here's why you exercise so much and still can't lose weight

Story highlights

  • People who exercise a lot may hit a plateau above which they do not burn more calories
  • Experts think we may have evolved to limit our calorie burn to keep from starving
  • You may be able to break the ceiling by changing up your exercise regimen

(CNN)If you are intensifying your running regimen in hopes of losing weight, you might be running around in circles: There is a limit to how many calories we can burn through exercise, a new study suggests.

The grim message comes from a small study of a group of 332 adults living in the United States, Jamaica and Africa, some of them more sedentary and some more active. A team of researchers measured their activity level for seven days using an accelerometer, similar to the kind in the Fitbit and other wearable devices, and also measured the number of calories the participants burned over the week.