Does Exercise Burn Fewer Calories Than Expected?

A recent secondary analysis of a clinical trial examined the phenomenon of exercise-related energy compensation, and how it relates to our total caloric expenditure. It’s common knowledge that we correlate exercise with us burning calories, but does that mean we all see an increase in our total daily energy expenditure (TDEE)??

The study involved 29 individuals considered to be overweight or obese, who were assigned to either a group aiming to burn 8 calories per kilogram of body weight per week via exercise (8KKW), or a group aiming to burn 20 calories per kilogram of body weight per week (20KKW). They participated in a 24-week study, where researchers measured the participants’ TDEE using the doubly labeled water method 2 week before baseline and two weeks after the 24-week period. When participants showed at least 5% less-than-expected TDEE, researchers were classified as compensators – meaning they were experiencing exercise-related energy compensation. Exercise was supervised and involved either a treadmill or stationary bike. At baseline and the last week, the participants also stayed in a metabolic chamber from 8:00 a.m. to 7:00 a.m. the next day, which allowed for estimates of the participants’ 24-hour daily energy expenditure, basal metabolic rate, resting energy expenditure, and sleeping energy expenditure.

What did they find?

Not surprisingly, researchers found that overall, exercise increased TDEE, but 48% of participants (14 out of 29) were classified as compensators, burning 308 fewer calories per day on average than expected. In contrast, the 15 non-compensators burned 94 calories per day more than predicted.

So what does it mean?

Although researchers weren’t able to definitively pinpoint why the compensators didn’t burn as many calories, research has shown that exercise alone doesn’t always induce weight loss. The researchers suggest that exercise-related energy compensation may involve a reduction in calories burned during physical activity itself, rather than at rest, potentially due to increased exercise efficiency.

Importantly, the degree of energy compensation did not determine the participants’ weight changes. Non-compensators lost an average of 1.9 pounds, while compensators lost 3.1 pounds, and there was no correlation between the degree of compensation and weight change. This indicates that factors beyond energy expenditure, such as changes in calorie intake, are essential mediators of the effects of exercise on body weight. The study highlights the complexity of the relationship between exercise, energy expenditure, and weight management.

Ultimately, this study adds to a body of evidence showing that exercise, while capable of helping with weight loss, doesn’t exist in a vacuum. To ensure best results, attempts to lose weight via exercise should be considered alongside other important variables in weight management, like diet, sleep, and mental health.

To read the entire story, visit: https://pubmed.ncbi.nlm.nih.gov/38947494/.