A short period of exercise can increase a person’s implicit desire for desserts, according to a study published this July in the Journal of Health Psychology. The study provides the first evidence that a small amount of exercise increases approach motivation for dessert food images in college students.

Exercise can affect the attractiveness of food and has been shown to alter a person’s desire for certain types of food, as well as help with self-regulatory behaviors. However, research in this area has shown that exercise can both reduce urges for snacking and increase desirability for unhealthy foods.

This has led to the distinction between explicit and implicit food motivations. Explicit factors generally refer to cognitions that influence attitudes and motivations toward food, including personality differences, personal exercise motivations, or weight loss/maintenance goals. For example, a person may view exercise as way of justifying eating high-calorie foods or alternatively as a way to reduce consumption of high-calorie foods via a healthy lifestyle.

Implicit food motivations reflect physiological processes that underlie our behavior and are not influenced by our personality differences, goals, or attitudes. No previous studies have explored the relationship between exercise and implicit food motivations.

The study, led by Christine May from the University of Massachusetts Medical School, examined the effect of exercise on implicit approach motivation to dessert food images. 88 students were divided into 2 groups: one group rode a stationary bicycle for 20 minutes at a moderate intensity; and the control group completed computerized working memory tasks for 20 minutes. Before and after this they all completed a test designed to measure their approach or avoidance tendencies toward either appetizing desserts (chocolate, cake, ice cream and brownies) or neutral items – the test assesses automatic/implicit motivational responses.

The results showed that the students randomized to the exercise condition became more approach oriented toward desserts compared to individuals in the cognitive task condition. This was even after controlling for group differences in disordered eating, task difficulty, and changes in negative affect.

“The data from this study suggest that there is an implicit, “bottom-up” desire for food after a bout of exercise. From an evolutionary perspective, individuals need to consume energy (i.e. calories) in order to survive and maintain bodily functions”, the researchers concluded. They also pointed out that the sample in the study consisted of mainly average weight undergraduates, and “it is possible that these individuals had a natural inclination to replenish the calories they lost during exercise.”