You probably know the scenario: you're out at a restaurant and you’re absolutely stuffed, but somehow you manage to find room for some chocolate fudge cake and cream. You're full after half a plate of chips, but you somehow manage to polish them off anyway. A new study investigating the mechanisms behind overeating sheds some light on why this is so often the case, and what biological processes are going on in the background.
Apparently, it’s all down to a hormone called GLP-1 (Glucagon-like Peptide-1), which is thought to play a role in obesity as well. Researchers from Rutgers University in the US were able to show that increased levels of GLP-1 stopped a group of mice from eating more than they needed. When the GLP-1 was suppressed, the animals went above and beyond their normal caloric needs for the day.
GLP-1 was found to block the production of dopamine, a neurotransmitter that scientists believe encourages the body to keep on doing whatever it's currently doing. There are links between dopamine and fatty foods - which may be why many of us overeat - but GLP-1 stops this process in its tracks. In other words, GLP-1 gets in the way of the brain's reward system for eating fatty foods.
The mice were given access to foods that resembled a normal diet and foods that were high in fat. The researchers used a synthetic module to introduce GLP-1 in some of the mice, and found that those that didn't get the boost were more likely to keep on eating - that was true with the normal diet, but even more so with the fatty diet.
As the digestive systems of mice are similar to our own, the findings of the study could help treat obesity and overeating. It could also help to explain how the digestive system is linked to the brain.
The results have been published in Cell Reports.
"Overeating, which causes obesity, can be considered a food addiction, a neuropsychiatric disorder," one of the researchers, Zhiping Pang, said in a press release. "By finding out how the central nervous system regulates food intake behaviour via GLP-1 signalling, we may be able to provide more targeted therapy with fewer side effects."
One theory now given more plausibility is that a GLP-1 deficiency in the brain could cause us to eat more than we really should in terms of calories. As Pang explained to Katherine Ellen Foley at Quartz, while GLP-1 booster treatments have been offered to diabetes and obesity patients in the past, they come with complications for other parts of the body that are much better avoided.