High gut hormone levels make you feel full: Study
A low GI (glycaemic index) meal leads to a feeling of satiety, researchers said on Tuesday in a finding they say is a first step in understanding the impact of GI foods on weight control and obesity.
GI is a ranking assigned to carbohydrates according to their effect on the body's blood-sugar levels. A low GI meal takes longer to digest as a result releases sugar into the bloodstream more slowly than a high GI meal.
A low GI diet is known to cause reduced appetite but how this happens has been unknown so far. Researchers from King's College London, the first to study how a low GI meal produces satiety, presented their findings at the annual Society for Endocrinology BES meeting on Tuesday.
They found that low GI meals increase the production of gut hormone glucagon-like peptide 1 (GLP-1). GLP-1 is a hormone that has been shown to cause a feeling of fullness and suppression of appetite.
"These are exciting results," said Professor Peter Emery, head of Department of Nutrition and Dietetics, and one of the paper's authors. "The findings are an important first step in understanding how low GI foods can help address issues of weight control and what part they should play in a balanced diet."
Researchers, including Dr Tony Leeds and Dr Reza Norouzy, looked at the effects of a single low versus high GI meal on gut hormone levels in 12 healthy volunteers.
Each participant ate an identical medium GI meal for dinner, fasted overnight and was given either a low (46) or high (66) GI meal for breakfast. The volunteers' blood samples were collected every 30 minutes for 150 minutes. Their levels of gut hormone GLP-1 and insulin were also measured.
Researchers found that volunteers who ate a low GI breakfast had 20% higher levels of GLP-1 and 38% lower levels of insulin, compared to those who had consumed a high GI breakfast.
The results show that eating a low GI meal increases GLP-1 production and suggest a physiological mechanism as to why a low GI meal makes one feel fuller than a high GI meal.
"GLP-1 is one of the most potent hormones for suppressing appetite," said Norouzy. "Our results show for the first time the direct effect of a single GI meal on gut hormone levels."
"Our results suggest that low GI meals lead to a feeling of fullness because of increased levels of GLP-1 in the bloodstream. This is an exciting result which provides further clues about how our appetite is regulated, and offers an insight into how a low GI diet produces satiety," he said.
Norouzy added that this is a preliminary study involving a small volunteer group. "We now need to expand these findings and look at the effects of low versus high GI meals in a larger cohort of people," he said.
China Daily
(China Daily 03/19/2009 page11)
