Appetite is a complex phenomenon controlled by many neurochemical and hormonal signals, as well as psychological and social factors.
An article by a group of investigators lead by Gilles Mithieux from the French research body, INSERM, published in the journal Cell Metabolism, may explain why many people on high protein diets, like Atkins, report a reduction in their hunger pangs.
The study was done in rats that were fed a high protein diet. It was found that this diet increased the activity of genes involved in glucose production in the animals’ small intestine. This increased glucose production was sensed by the liver and then chemical signals were relayed to the brain indicating that the stomach was full, and thus causing the animals to reduce their food intake.
Previous research has indicated that high protein diets do not seem to do anything magical to metabolism, but may work by reducing the overall intake of calories. The same effect on intestinal glucose production can be achieved with a low carbohydrate diet, showing us that both types of diet are probably working by the same mechanism. There are some interesting points here:
1. This study re-affirms the importance of calorie reduction as the key to weight loss, and it answers the “how” question: how do some of these diets work?
2. It illustrates something that is not widely known: glucose is produced in many parts of the body and glucose is a key regulator of appetite. The vast majority of the glucose circulating in your blood has come from the liver, and not directly from what you eat. It is only if you soak yourself in simple carbohydrates, as might happen if you drink something containing a lot of sugar, that your blood glucose may rise. But in most people who have healthy metabolism, the body rapidly corrects the elevated glucose.
3. The types of genes being stimulated to work in the intestine cannot be stimulated indefinitely. Eventually they will stop responding. You can only fool the body for a limited amount of time. That would explain why so many people who lose a lot of weight on one of the popular diets, find that the weight does not stay off. The lesson must be to make small but significant dietary changes, with the emphasis on keeping your food intake balanced. (You might like to have another look at my entry from January 6th)