Protein suppresses hunger better than simple sugars

Conventional wisdom suggests that meals high in simple sugars first lead to a rapid rise and then an abrupt drop in blood sugar levels, which in turn leads to renewed hunger more quickly than eating a protein-rich meal. Australian scientists were able to show that a protein-rich meal does indeed suppress hunger better than a carbohydrate-rich meal, although the difference could be attributed to hormonal reactions rather than blood sugar levels. The test subjects were each given a 300-calorie meal consisting of whey protein (52g protein), casein (52g protein), glucose (7g protein) or lactose (7g protein). Three hours later, the test subjects were able to help themselves to an all-you-can-eat buffet. This showed that the snacks with a high protein content satisfied hunger best, whereas the subjects who had received the glucose meal ate the most from the buffet. Blood glucose and insulin levels rose fastest and most strongly in the glucose group, but after 2 hours blood glucose and insulin levels were the same again in all subjects. The composition of the snack influenced hormones that control appetite and are responsible for a feeling of satiety. Protein-rich meals increased the release of the hormone cholecystokinin (CCK), which suppresses hunger, whereas carbohydrate-rich meals increased the release of the hormone ghrelin, which triggers a feeling of hunger. Protein-rich meals suppress hunger by increasing CCK secretion while preventing an increase in ghrelin secretion. (Journal Clinical Endocrinology Metabolism, 91: 1477-1483, 2006)