Influecing levels of gut hormones released before and after meals, may be how physical exercise helps to regulate body weight, say researchers presenting to the annual meeting of the Society for the Study of Ingestive Behavior (SSIB) that is taking place this week in Clearwater, Florida, in the US.
We already know from previous studies that vigorous exercise like running increases sensitivity to leptin, a hormone secreted by fat cells that limits food intake.
Now, researchers from Johns Hopkins University in Baltimore, Maryland, suggest they have found more mechanisms that show the benefits of exercise in helping to control body weight.
They told the press that they studied levels of gut hormones released in rats after they ate a tasty meal. They did this both before the rats exercised in running wheels and also afterwards.
They found that after consuming a tasty meal, rats with a lot of running experience had higher levels of amylin in their blood. This pancreas-secreted hormone is known to inhibit food intake, slow digestion, and reduce the rate at which glucose enters the bloodstream.
These same rats also showed a faster rate of reduction of the hormone ghrelin after the meal. Ghrelin, an appetite stimulator, is secreted by the stomach and the pancreas and usually rises before a meal and falls afterwards.
And when the rats with a lot of running experience were given the hormone cholecystokinin (CCK), the researchers found they decreased their food intake more robustly than their sedentary counterparts. Among other things, CCK is a hunger suppressant secreted in the gut.
One of the researchers, Dr Nu-Chu Liang, a post-doctoral fellow at Johns Hopkins, said their findings suggest that exercise helps control body weight by modifying how meals release gut hormones that regulate food intake. It may also change people’s sensitivity to these gut hormone signals.
Liang added “these findings suggest that both body and brain mechanisms are involved in the effects of exercise to modulate food intake”.
A grant from the National Institutes of Health paid for the research.
Written by: Catharine Paddock, PhD