Dr. Mercola looks at the science behind high protein diets:

Scientists suspected amino acids like leucine activate highly active mTOR enzymes in the hypothalamus, a sector of the brain that regulates appetite in humans and rats. After injecting a 1 microgram dose of leucine in the brains of rats near the hypothalamus, these animals ate 20 percent less food over the following day.

The results were far more dramatic after a 24-hour fasting: Rats not given a leucine injection gained three times more weight than those that received one.