Wednesday, March 18, 2009

Low G.I. Meals Affect Appetite Reducing Hormone Production

It's been discovered that eating a meal with a low GI (glycemic index) increases gut hormone production, which leads in turn to suppression of appetite and the feeling of fullness. This new research was presented at the annual Society for Endocrinology meeting in the U.K.

Researchers from King’s College (London) studied the effects of a low versus high GI meal on levels of gut hormones. It has long been known that eating low GI foods seems to provide a feeling of fullness, but this is the first study to provide clues as to how it works -- there actually appears to be a physiological effect going on.

Glycemic Index (GI) is a ranking assigned to carbs based upon their effect on the body’s blood sugar levels. It's already been shown that a low GI meal takes longer to digest and releases sugar into the bloodstream more slowly than a high GI meal. High GI foods include white bread, donuts and cornflakes, whereas multi-grain breads, soy milk and most fruit and vegetables are all classed as low GI foods.

Dr Reza Norouzy and colleagues at King’s College London looked at the effects of a single low GI meal and compared the gut hormone levels in twelve healthy volunteers with those who had eaten a single high GI meal. Blood samples were then taken every 30 minutes for 150 minutes, and levels of the gut hormone glucagon-like peptide 1 (GLP-1) and insulin were measured. This particular hormone, GLP-1, is produced by the gut and it has been shown to cause a feeling of fullness and suppression of appetite.

Volunteers who ate a low GI breakfast had 20% higher blood plasma levels of GLP-1 compared to those who had consumed a high GI breakfast. These results show for the first time that eating a low GI meal increases GLP-1 production. This means that there is indeed a physiological response to the feeling of fullness you get after eating low GI foods. Click on the headline of today's post if you want to see a chart of various foods and their Glycemic Index positioning.


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