Serotonin controls appetite and metabolism independently

Source: Scientific American’s The Skinny on Fat: You’re Not Always What You Eat

Have you ever wonder why some people can just gobble down foods but still stay skinny? Recent study done by the scientists at the University of California, San Francisco, (U.C.S.F.) may shine some light on the matter.

Serotonin, a neurotransmitter, is often used by diet drugs to control appetite. But some people regain their weight as soon as they stop taking the pills, even though they do not increase calorie intake. It is thought that serotonin could also play a part in how the body handles the food. And it is the interplay of food intake and the rate of metabolism that determines the weight and fat percentage of the body.

A physiologist at U.C.S.F., Kaveh Ashrafi, and his colleagues tested on roundworms (Caenorhabditis elegans), which are genetically similar to mammals. The fundamental mechanisms working in the organism are also found in humans. They produced genetically defective roundworms that express only a group of proteins controlled by serotonin, some are associated with appetite, others influence metabolism. They discovered that if they blocked the proteins linked to appetite, the worms would change their eating pattern, but their fat contents remained the same. On the other hand, when the proteins related to metabolism is suppressed, the worms would slim down even though they continued to eat the same amount of food.

This shows that the body processes the food differently. The mechanism lies within the proteins that serotonin controls. The transmitter has an effect on both the appetite and metabolisms rate, each is independent of the other. That’s why people with similar eating and exercising habits can have very different weights.