Stock photo of a man trying to exaggeratedly open a jar of pickles.

Post-exercise hunger could thwart your efforts to lose weight

Exercise is the healthiest, most efficient way of losing those extra pounds. However, a new paper comes to show how physical activity can influence our appetite and desire to eat — and how best to manage these, if we want to lose weight.

Stock photo of a man trying to exaggeratedly open a jar of pickles.
Image credits Ryan McGuire.

Let’s face it — most of us have become a bit plump during the last year. Between the drop in physical activity as we quarantine in our homes and the comfort eating to soothe our troubled souls, it’s perfectly understandable. But most of us also harbor secret plans to shed the pounds once things quiet down.

A new paper could help us in that regard. Published by a team of researchers at the Technical University of Munich (TUM) and the University of Nebraska (USA), it details how people can feel the need to eat more food and faster after exercising. This, in turn, can sabotage our efforts of actually slimming down, and can make us give up on it entirely.

Food for thought

“In the sports context, we have the phenomenon of people overeating after physical activity,” said Prof. Köhler, Professor of Exercise, Nutrition, and Health at the Technical University of Munich. “People want to reward themselves and their bodies for being active. So we use a hypothetical experiment to find out why people eat more after exercise compared to when they don’t exercise.”

“Based on this study, we were able to show for the first time that certain characteristics, such as the amount and ‘urgency’ with which a person wants to eat, change over the course of physical exertion. These findings help us develop new interventions to optimize weight loss through exercise.”

The trial followed a randomized crossover structure involving 41 healthy participants (23 women, 18 men) between 19 and 29 years old with an average BMI of 23.7. They were randomly assigned to either a 45-minute exercise session or a 45-minute rest period. Either was performed during the participants’ first visit to the lab. Every participant was then asked to perform the other task upon their second visit.

After this, the real experiment would begin: the team wanted to see how exercise influenced the participants’ choices in regards to the amount and timing of food intake. Before the trials, participants filled out an electronic questionnaire that assessed how hungry or satiated they felt, had them pick between foods that differed in the time of consumption (i.e. immediately or delayed by preparation, for example), how much food they felt like eating (which they did by selecting the desired portions of each food item).

These preferences were recorded both for immediate and later consumption (i.e. they were asked to predict their food preference for four hours later). Then, the participants engaged in the exercise task, which consisted of 45 minutes of aerobic exercise on a bicycle ergometer. Upon completion, they were asked to fill the same questionnaire out a second time, and a third time half an hour later. Participants in the control (rest) group went through the same procedure, but with rest instead of exercise.

All in all, the team explains, exercise led to participants choosing a greater amount of food both immediately after the exercise and 30 minutes later, as reflected in their questionnaires. It also made them pick food that would be immediately available for consumption on both questionnaires.

“The actual results suggest that physical exertion can entice those who do sport to eat larger amounts of food more quickly after the training session,” says Prof. Köhler.

“Since weight loss is a main motivation for exercising for many, and failure to achieve the desired weight loss makes it likely to quit exercising, it could be a good strategy to think about what you want to eat afterwards before you start to exercise.”

The team is currently researching which strategies work best in improving the long-term effectiveness of training programs. But until they can pinpoint the most effective approach, just know that exercising will make you want to eat, a lot, and quickly. Keeping the reins on this can make or break your efforts to lose weight.

The paper “Exercise Shifts Hypothetical Food Choices toward Greater Amounts and More Immediate Consumption” has been published in the journal Nutrients.

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