Exercise's Effect on Appetite Regulating Hormones

 Research has previously proven that exercise can cause an increase in an appetite-stimulating hormone. Research is beginning to aim towards finding the connections between specific types of activity and the appetite regulating hormones they effect to optimize weight loss routines.

Many processes within the body can be attributed to hormones.  Previous research had confirmed the idea that there are particular hormones responsible for appetite and energy balance.  Leptin, a “satiety hormone”, is produced in adipose tissue (also known as fat cells) and responsible for energy balance and feeling full after meals.  This signal allows the body to know when to stop eating, and therefore can be connected to the process of weight loss.  It would be easy to assume that people who are obese have a lower level of leptin, and therefore have a harder time feeling full after consuming meals, but this is not the case.  It has been found that obese people actually have the highest levels of leptin, however their bodies do not sense these levels and therefore can be considered as “leptin-resistant”.

Ghrelin is a hormone secreted by specialized cells in the stomach that acts on the brain to trigger a rise in appetite.  Levels of ghrelin rise before meals and fall shortly after.  High levels of ghrelin have been attributed to making high calorie foods look more appealing.  Because these hormones play a significant role in the amount of calories consumed and weight loss, recent research in obesity is looking towards how the body utilizes these hormones and what can effect them for possible solutions to overconsumption of food.

Past research had shown that exercise can increase levels of ghrelin in the body, therefore you could become hungrier than if you weren’t to have exercised.  Recent research at the University of Wyoming has found an interesting twist relating to the type of exercise and its effects on ghrelin and the satiating hormones (including leptin) in the body.

The research completed by the University of Wyoming sought to find a connection between appetite-related hormones and exercise.  The group involved in the study was a group of women (either walkers or runners) who exercised for 60 minutes every other day, while resting on alternating days between for 60 minutes.  After either exercising for an hour or resting for an hour, the participating women were taken to have blood drawn to measure the levels of hormones post-60 minute interval and then directed towards a buffet to measure and compare the amount of calories consumed.

Similar to results from other research, the women who ran were found to have an increased production ghrelin than the women who walked or rested.  Remembering that ghrelin is responsible for initiating meal and increasing appetite along with the idea that exercising makes you hungrier, you would think that the runners would have had the greatest appetite and consumed the most calories from the buffet. However, contrast to relevant research that says that an increased level of ghrelin will lead to an increased appetite, these women were the group that consumed hundreds of calories less at the buffet than those who did not have the higher levels of ghrelin.

So why did the women with the higher levels of ghrelin eat less than those that did not produce a higher amount?

Researchers believe that the hormones responsible for satiety (leptin being amongst them) could have overridden the effectiveness of the higher level of ghrelin, allowing the runners to become satiated sooner.  The groups of resting women and walkers were found to consume more calories at the buffet than necessary.

While research is still preliminary, it can be concluded that it would appear that moderate exercise (similar to jogging or running) may allow the body to better control the hormones responsible for hunger and satiety, unconsciously leading to those who exercise to control their portions at meals.  Also, since walking had no effect on the satiety hormones, those who are looking to promote weight loss by increasing their activity through walking might be at a disadvantage.