Fat can stimulate the secretion of the hormone cholecystokinin from the small intestine, which helps to keep the appetite sated. (Photos.com)
While a number of dietary approaches have been advocated for weight loss, my preference is for diets that are relatively rich in protein and low in carbohydrate. And one major reason for this is the fact that, calorie for calorie, protein sates the appetite generally more effectively than fat or carbohydrate. Therefore individuals who up their protein intake often find they are eating less because they’re less hungry.
However, how much satisfaction is derived from a meal once it’s eaten and for the next few hours will not depend solely on its protein content (and how much is eaten, of course). Fat and carbohydrate can also have distinct effects on feelings of fullness too.
Fat, for instance, can stimulate the secretion of the hormone cholecystokinin from the small intestine, which helps to keep the appetite sated. Carbohydrates are important too, and studies show that those that release sugar relatively slowly into the bloodstream (lower glycemic index carbs) are generally more satisfying than those that release sugar more quickly [1].
One reason for this relates to the fact that faster sugar-releasing carbohydrates tend to cause the secretion of larger amounts of insulin, which can drive blood sugar levels down to lower-than-ideal levels. The end result can be a ravenous appetite and sometimes craving for carbohydrates (often something sweet), about two to four hours after a meal. Even slower-releasing carbs can have this effect if we eat enough of them.
I was interested to read about a study presented yesterday at the Endocrine Society’s annual meeting in Washington, D.C. The study assessed the effect on satisfaction of two diets of different macronutrient composition. One diet provided 55, 27, and 18 percent of calories from carbohydrate, fat, and protein respectively. The other provided 43, 39, and 18. In other words, one diet offered less carb and more fat than the other. The diets were not designed to lead to weight loss and were each tested for one month.
The results of this study have been reported to show that those eating the lower-carb diet reported feeling fuller for longer after a meal.
One of the authors of this study, Dr. Paula Chandler-Laney, reportedly commented that this effect might have to do with blood sugar control. It’s possible that it might also have something to do with the higher fat in the lower carb diet.
Dr. Chandler-Laney also commented that a moderate reduction in carbohydrate intake may make individuals less susceptible to weight gain because of the effect such a diet may have on feelings of fullness and presumably overall food intake. And she’s right.
But the other thing here is that less carb and less insulin in the body will likely mean less fat accumulation in the body for biochemical reasons that were explored in previous articles.
References:
1. Roberts SB. High-glycemic index foods, hunger, and obesity: is there a connection? Nutrition Review 2000 58:163–169
Dr. John Briffa is a London-based physician and health writer with an interest in nutrition and natural medicine. His Web site is drbriffa.com
