A new imaging study suggests if we were to take a pill based on two simple gut hormones we would eat less because it would fool the brain by signalling we’re full even if we’re not. The researchers scanned the brains of the same volunteers at two different times: just after they fasted and took a dose of the hormones, and just after they had eaten a meal. Both brain patterns showed reduced activity in the areas known to control appetite.
You can ready how researchers from Imperial College London and GlaxoSmithKline carried out the study in a paper published earlier this month in Cell Metabolism.
They hope that a pill based on one or both of the hormones could reduce the prevalence of obesity. They suggest it may also encourage healthier eating because we tend to choose foods higher in calories when we are hungry.
Senior author Dr Waljit Dhillo, a Professor in Endocrinology and Metabolism and Consultant Endocrinologist at Imperial College London, told the press:
“Obesity is a major and rising problem.”
“The central dogma is we need to eat less, but that doesn’t work so well. Understanding how the brain makes us feel hungry and full is an important issue for therapy,” he added.
Dhillo explained that as the time for our next meal approaches, our throughts and our brains get excited. Then, after we’ve eaten and our hunger is gone, thoughts about the same foods don’t have the same effect.
Scientists have already shown that the hormones PYY and GLP-1 (short for peptide YY and glucagon-like peptide 1), which enter the bloodstream soon after eating, appear to play a part in this effect. In studies, volunteers who took one or other of the hormones experienced reduced appetite and ate less.
But until this study, we knew little about how these hormones affect the brain.
For the study, Dhillo and his team used functional magnetic resonance imaging (fMRI) scans to compare the brain activity of healthy normal weight volunteers shown images of tasty food at two different times: once just after taking the hormones in a fasted state (some took one, some took the other, and some took both hormones) and before eating a buffet meal, and the other time when they were full after eating a standard meal and were about to eat a buffet meal.
The results showed that the reduction in brain activity under both conditions was very similar. There was less activity in areas known to control appetite behavior.
“Participants had eaten no breakfast, but the pattern of their brain activity looked as if they had,” said Dhillo.
“There brain was tricked and they subsequently ate less of a buffet meal.”
Each hormone curbed appetite on its own, but the strongest effect was when they were taken together.
The researchers said their results confirm that PYY and GLP-1 are important influencers of fullness and may have potential as treatments.
Dhillo said it might be possible one day to mimic the effect of these hormones in a pill to be taken daily or weekly for the treatment of obesity.
Drugs that mimic GLP-1 are already prescribed for the treatment of diabetes.
Written by Catharine Paddock PhD