"It's not that exercise doesn't burn fat," Live Science quoted Edward Melanson, associate professor of medicine at the University of Colorado as saying.
"It's just that we replace the calories. People think they have a license to eat whatever they want, and our research shows that is definitely not the case. You can easily undo what you set out to do," he added.
During the study, Melanson set out to measure whether people were able to burn more calories for the 24 hours after a workout compared to a day with no exercise.
On exercise days, the participants rode stationary bikes until they had burned 400 calories. Their pre and post exercise diet was controlled.
The study showed that throughout the groups, there was no difference in the amount of fat burned in the 24-hour period either with or without exercise.
They are clear on their current message. "We suggest that it is time to put the myth that low intensity exercise promotes a greater fat burn to rest," Melanson said.
"Clearly, exercise intensity does not have an effect on daily fat balance, if intake is unchanged," he added.
The findings appear in Exercise and Sport Sciences Review.