Exercise and appetite is a hotly debated topic at the best of times, but now new research suggests exercise may not “work up an appetite” after all. So, does exercise make us eat more or not?
After finishing a hard session at the gym, some people will argue that exercise revs up their appetite and that they’re left gobbling down more kilojoules than they burnt off. Ask others though they’ll give you a completely different answer – food is the last thing on their mind following a workout. But, whether exercise works up an appetite or not may depend on a number of things including the type of exercise performed, as well as how regularly you exercise.
According to new research published in the journal Medicine & Science in Sports & Exercise, 45 minutes of moderate-to-vigorous exercise in the morning actually reduces a woman’s motivation for food irrespective of body mass index. During the study, normal weight and clinically obese women walked on a treadmill for 45 minutes and then, within the hour, had their brain waves measured while they looked through images of food and flowers. Fast forward a week, and the same experiment was conducted at the same time of morning, but this time there wasn’t any exercise. The 45-minute walking bout not only produced lower brain responses to the images, it also resulted in more physical activity (as measured by accelerometers) for the following 24 hours and the women did not eat more food to “make up” for the extra kilojoules burned in the exercise. However, the researchers concluded that there still needs to be research done to determine how long the diminished food motivation lasts after exercise and to what extent it persists with consistent, long-term exercise.
Along with diminishing our motivation for food, exercise may suppress our appetite by affecting our hunger hormones. According to a small study from the UK, running for an hour reduces the level of the hunger-promoting hormone ghrelin and increases the level of peptide YY, a hormone that tells us to stop eating. Participants in the study also filled out surveys in which they rated their hunger levels at various points. These changes in hunger levels were seen for about 2 hours, including the time they spent exercising. Even more interesting was that the study also found that vigorous exercise suppressed appetite more than a resistance training session, which was only found to affect ghrelin levels (didn’t change the levels or peptide YY). While these findings suggest the type of exercise may affect our appetite, additional research suggests how regularly we exercise may also have an impact on our food intake.
Research from Queensland University of Technology and the UK’s University of Leeds found that when people became more active they also became more satisfied with the same amount of food, which suggests that the habit of exercising regularly may help us to regulate our appetite better. In other words, regular exercise may help us get more in tune with our hunger levels. This supports earlier research that shows that habitual exercisers have better appetite regulation than their sedentary, less active counterparts. But, what’s also true is that we’re not all the same and when you through weight loss into the mix there are individual differences in the effect exercise has on appetite.
Even if you’re not exercising to lose weight, if you are someone who rewards themselves with their favourite muffin or cake post-workout, all that hard work in the gym may be a waste of time. In fact,finishing your workout off with a slice of banana bread and a coffee will give you more kilojoules than you burnt off during your workout! So, while it’s nice to use exercise as an excuse to eat more, for some of us the desire to eat may actually come from our own beliefs and reward behaviours, and not an increase in appetite after all.
Do you eat because you are hungry or because you want to reward yourself for all your hard work?