When you choose your post-workout snack determines how healthy it is

Making the decision before working out to eat a healthy snack after working out may lead to more healthy snacking, according to a study recently published in Nutrients. This is when you are most likely to favor choosing a healthy snack, such as an apple instead of a brownie, for example.

“We found that there was very little research on this very tangible thing that I think everyone can relate to. If your goal is to lose weight, then I would say our findings support that you're better off making the choice...not when you're hungry after your workout, but instead before you go to the gym,” said senior author Karsten Koehler, PhD, assistant professor, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE.

“There have been a lot of lab studies that have looked at appetite and hunger,” he added. “Most of these studies have found that right after exercise, you seem to be less hungry. I've always looked at these studies and wondered: Does it have such a strong impact that you can use this window after you exercise to say, ‘Because I'm not hungry, I'm going to make a really good choice about what I eat?’ But knowing myself and many other exercisers, there's also the notion that after you exercise, you want to reward yourself.”

To determine whether the timing of making a snack choice affects healthy vs unhealthy food choices after a workout, Dr. Koehler and colleagues conducted this study.

They included data from 256 participants who were visitors to a university recreational center (mean age: 22.1 years; 54.7% male; average BMI: 24.7 kg/m²). Participants were randomized to choose a post-workout snack either before or after their workout, and then exercised once, for a mean duration of 65.3 minutes. Snacks consisted of either an apple or a chocolate brownie.

In all, 73.7% of those who selected a snack pre-workout selected the apple compared with 54.6% of those who chose post-workout. Brownies were chosen by 13.9% vs 20.2%, respectively, and no snacks were selected by 12.4% vs 25.2%. 

These choices were significantly different depending on when they were made (P < 0.001), with an approximately 20% decrease in those choosing an apple pre-workout compared with post-workout.

The only baseline characteristic that contributed to snack choice was BMI. Subjects who were overweight or obese (BMI greater than 25 kg/m²) were significantly less likely to select a brownie than those with a BMI of less than 25 kg/m².

Their findings also highlight two other theories. The first is one of compensatory eating, which suggests that people consume more high-calorie foods after exercising to compensate for calories expending. The second theory is that of exercise-induced anorexia, which holds that exercising may suppress the hormones related to appetite and cause less eating.

They found evidence of both. First, the theory of compensatory eating was supported by the 6% increase between the before- and after-exercise groups who chose to snack on a brownie. Next, the theory of exercise-induced anorexia was backed by the over two-fold increase in those who declined a snack after exercising compared with before (25.2% vs 12.4%, respectively).

“Using a behavioral intervention approach, we show that a very simple modification—making a choice about a post-exercise snack either prior to or following the completion of the exercise bout—significantly alters the snack choice. Our findings indicate that the likelihood of choosing an apple, a food typically considered as “healthy,” is about one third (33.5%) greater when the choice is presented prior to engaging in exercise; however, when the choice is presented following the exercise bout, individuals are approximately 39% more likely to choose a brownie, a food typically considered as “unhealthy,” and 12% more likely to decline either snack option,” concluded Dr. Koehler and colleagues.

This study was supported by the University of Nebraska’s Food for Health Collaboration Initiative.