We all are very aware of the numerous benefits that accrue from participating in regular exercise. While these benefits should be widely promoted, it is also important to acknowledge that exercise may impact other health behaviors — and not always in a positive direction. For instance, some individuals may license themselves to indulge in unhealthy eating after exercise, thereby undoing some of the benefits achieved — particularly in relation to energy balance. Accordingly, understanding the relationship between exercise and subsequent food intake is important to maximize the potential benefits to be gained from regular physical activity.
In our study, as presented in the October 2017 issue of MSSE, we examined whether manipulating ‘choice’ during a bout of acute exercise would influence subsequent food choices and overall energy intake. Fifty-eight young healthy men and women were pair-matched based on age, sex, fitness, height and weight before randomization to either a ‘choice’ or ‘no choice’ exercise condition using a between-subjects yoked design. Participants randomized to the ‘choice’ condition were provided with choice of exercise mode, intensity, duration, time of commencement and the type of background music played. Those in the alternative group (no choice) were required to complete the exercise session under the conditions chosen by their matched, i.e., their ‘yoked’ partner. This study design allowed us to manipulate choice between participants while standardizing the mode, intensity and duration of exercise to ensure equivalent energy expenditure. The effect of choice in exercise on subsequent food intake was assessed using a buffet-style laboratory test meal administered after the activity.
Interestingly, we found that those who exercised under controlled (no exercise choice) conditions consumed more food overall (587 versus 399 kcal) and, specifically, more food from unhealthy food sources compared with their counterparts who were provided with choice in exercise (337 versus 188 kcal). Providing participants with the ability to make their own choices regarding the nature of exercise also resulted in higher ratings of enjoyment and value which may have implications for long-term exercise adherence.
Overall, these findings suggest that facilitating choice and autonomy in exercise should be an important consideration for exercise prescription and instruction. Indeed, if you exercise with autonomy — because you choose to, you can see the value and you enjoy it — you may be less likely to eat unhealthy foods in the hours that follow. In contrast, with limited choice, or when participating in exercise because you feel you must, or for reasons not under your control, you may be more likely to eat unhealthy foods.
These findings are important for people to be aware of if they are exercising themselves or involved in motivating others to exercise. That is, exercising with choice may be key to maximizing the benefits of exercise and not compromising eating behavior in the aftermath of an exercise session.
Natalya J. Beer, B.Sc. (Hons), and Kym J. Guelfi, Ph.D., are exercise physiologists and researchers at The University of Western Australia in Perth, Australia. Their research focuses on the relationships between exercise, appetite and food choices, together with the implications for weight management.
This commentary presents the authors’ views on the topic of a research article which they had published with their colleagues in the October 2017 issue of Medicine & Science in Sports & Exercise® (MSSE).