Researchers have identified a substance in blood that is produced when people exercise. Researchers analyzed blood plasma compounds in mice who had just finished intense treadmill running. They found a modified amino acid called Lac-Phe, derived from lactate. Lactate is the chemical that is responsible for the burning sensation in muscles after a strenuous workout. The substance also reduces food intake and decreases obesity in mice.
In mice with diet-induced obesity (fed a high-fat diet), a high dose of Lac-Phe suppressed food intake by about 50% compared to control mice over a period of 12 hours without affecting their movement or energy expenditure. When administered to the mice for 10 days, Lac-Phe reduced cumulative food intake and body weight (owing to loss of body fat) and improved glucose tolerance.