Why physical activity makes you eat more and how to cope

Globally, 39% of adults were overweight in 2016, according to statistics from the World Health Organization. In the United States, the prevalence of obesity was 42.4% in 2017/2018, according to a survey by the National Center for Health Statistics (NCHS).

At the same time, millions of people want to lose weight. Exercise is an important option to achieve this. After all, sports burns more calories than sitting, standing or lying down.

But what influence does sport have on (direct) eating habits? Scientists from the Technical University of Munich (TUM) and the University of Nebraska (United States) have looked into this question for the first time.

Randomized study

“In the context of sport, we have the phenomenon of 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 their activity. So we use a hypothetical experiment to find out why people eat more after exercise compared to when they don’t.

Karsten koehler

First author Prof. Dr. Karsten Koehler, Professor of Exercise, Nutrition and Health at the Technical University of Munich (TUM). Credit: Andreas Heddergott / TUM

The aim of a randomized crossover study was to investigate the influence of exercise on hypothetical decisions about how much and when to eat. To this end, 41 healthy participants (23 females, 18 males) aged 19 to 29 with an average BMI of 23.7 were randomly assigned to either a 45-minute exercise session or a rest period. of equal duration on the first visit and completed the other study condition on the second visit.

Subjective assessment of hunger and satiety

In each case, the training group responded to an electronic questionnaire before physical activity on their subjective assessment of hunger and fullness, the preferred amount of food to eat, and the choice between foods that differed at the time. of consumption. Subjects indicated their preferences for the amount of food by listing the desired serving size of each food. Preferences were obtained for the immediate and subsequent consumption of the food after four hours.

After completing the first questionnaire, participants performed 45 minutes of aerobic exercise on an ergometer bike. Immediately afterwards, they completed the electronic questionnaire a second time and then a third time after a 30 minute break. The procedure for the untrained group was the same; instead of 45 minutes of physical activity, these participants took a break.

Compared to the rest break, exercise allowed for a greater increase in the amount of food chosen, both immediately after exercise and 30 minutes after. Physical activity also resulted in a greater increase in preference for immediate food consumption both immediately after exercise and 30 minutes after.

Weight loss through 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 during physical exertion,” said the Professor Köhler, ranking the results. “These results help us develop new interventions to optimize weight loss through exercise.”

“The actual results suggest that physical exertion may cause those who exercise to eat larger amounts of food more quickly after training,” says Prof Köhler. “Since weight loss is the primary motivation for exercising for many, and not achieving the desired weight loss makes it likely to stop exercising, this might be a good idea. strategy of thinking about what you want to eat next before you start to exercise. “

The effectiveness of these and other possible strategies, how they can improve long-term compliance with training programs and contribute to favorable health outcomes through weight loss and whether the effect may possibly fade away, is the subject of current research by scientists.

Reference: “Exercise Shifts Hypothetical Food Choices to Greater Amounts and More Immediate Consumption” by Karsten Koehler, Safiya E. Beckford, Elise Thayer, Alexandra R. Martin, Julie B. Boron and Jeffrey R. Stevens, January 24, 2021, Nutrients.
DOI: 10.3390 / nu13020347

BMI is the most common formula for calculating weight. It is calculated by squaring the ratio of body weight in kilograms to height in meters. Values ​​between 18.5 and 24.9 are considered normal weight.

The research was funded by the Food for Health Collaborative Initiative at the University of Nebraska.

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