Does exercise make you work up an appetite or does hunger have nothing to do with whether or not you eat post-exercise?
Considering you’ve just torched a number of kilojoules during your training session, you would think you would be hungry. But while some people have an overwhelming urge to eat post-workout, for others food is the last thing on their mind. Despite many of us thinking hunger plays a role post exercise, whether you “work up an appetite” or not post-training, in reality it may have nothing to do with hunger at all and everything to do with the time of day and how regularly you exercise.
According to research published in the journal Medicine & Science in Sports & Exercise, exercising in the morning may reduce our motivation for food irrespective of body weight. During the study, normal weight and clinically obese women walked on a treadmill for 45 minutes in the morning. Post workout, the women had their brain waves measured while they looked through images of food and flowers. Fast-forward a week, and the exact same experiment was conducted at the same time of morning, but this time minus the exercise. Researchers found that 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, at present we do not know how long the diminished desire for food lasts for post-exercise and whether it persists with consistent, long-term exercise.
Along with diminishing our motivation for food, exercise may suppress our appetite by affecting our hunger hormones. A small study from the UK found that running for an hour reduced the level of the hunger-hormone ghrelin and increased the level of peptide YY, a hormone that tells us to stop eating. These changes in hunger levels were seen for about 2 hours, including the time spent exercising. The study also found that vigorous exercise suppressed appetite more than a resistance training session, which was only found to affect ghrelin levels, while levels of peptide YY stayed the same. While these findings suggest the type of exercise may affect our appetite, additional research suggests how regularly we exercise may also impact on our food intake post-workout.
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, suggesting that exercising regularly may in fact help us to better regulate our appetite. This supports earlier research that shows that habitual exercisers have better appetite regulation than their sedentary, less active counterparts.
Now if you’re reading this in pure disbelief and truly belief you eat more post-exercise, you may need to look at your eating behaviours. If you follow your workout with a slice of banana bread and a coffee, you may be using food as a reward for your hard session. Unfortunately, you’ve just eaten your way through more kilojoules that you burnt during the session. 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.
Photography: Scott Ehler
About the author
Caitlin Reid is a unique health professional with qualifications as an accredited nutritionist, accredited exercise physiologist and yoga teacher. Caitlin is passionate about all things health and wellness, and keeps up-to-date with the latest health research, which she uses when contributing expert advice to health, fitness, lifestyle and food companies. She is also the nutrition expert for the Women’s Fitness magazine, the dietitian for the South Sydney Rabbitohs and ambassador for Papaya Australia. Follow Caitlin on Instagram @caitlinareid or visit her website.