What Does Exercise Do To Appetite?Thursday, July 22, 2021
Although there is now a solid body of evidence showing that exercise alone has a rather minimal effect on body weight, I have met countless people who swear by how exercise helped them lose weight. Indeed, ‘not enough exercise’ is one of the most common ‘excuses’ I’ve heard from my patients and ‘I need to exercise more’ is probably the most common solution that patients consider for losing weight.
And clearly, there are those patients, who have lost significant amounts of weight with exercise, which simply cannot be explained by the number of calories burnt (which is generally far less than most people think).
This led me, several years ago, to postulate the hypothesis that some people lose weight when they begin an exercise program because it reduces their appetite, thus resulting in lower caloric intake.
However, as much as I love this hypothesis, it seems that the overall effect of exercise on appetite and energy intake is pretty neutral, at least according to a meta-analysis by Kristine Beaulieu and colleagues published in Obesity Reviews.
The researchers reviewed 48 articles that reported the relationship between an exercise intervention and changes in caloric intake, appetite, hunger, satiety, and other features of ingestive behaviour.
Despite noting that the vast majority of these studies were sadly of rather poor quality, there did not appear to be any significant impact of exercise on caloric intake – in either direction!
While this finding is consistent with the fact that exercise very seldom leads to any significant change in body weight, it does pose the questions of a) why some people claim that exercise helped them lose vast amounts of weight, and perhaps b) why regular exercise is associated with a greater likelihood of keeping weight off.
As the authors discuss, there are several influences of exercise on ingestive behaviour that may need to be considered (and for which there is some evidence). These include an improvement in satiety quotient as well as potential reduction in overconsumption due to alterations in impulsivity, dietary restraint, food reward/preferences, as well as the notion that the increased energy flux induced by exercise could generate better control of eating behaviour.
However, these mechanisms appear to be, on average, rather minimal in that they may support individuals attempting to reduce their caloric intake but on their own are unlikely to do so.
Obviously, irrespective of any effects on appetite or body weight, the health benefits of regular exercise are indeed profound and manifold. This applies to people of all shapes and sizes. So please don’t get discouraged when your exercise routine does not move those numbers on the scale.