Melatonin is a hormone produced by the pineal gland that regulates circadian rhythms and other physiological functions. It is involved in controlling body weight and metabolism. Studies show melatonin may play an important role in preventing obesity and related conditions like diabetes. Microdeletions on chromosome 16 that suppress melatonin receptor genes are linked to obesity. Melatonin appears to promote energy consumption and inhibit weight gain, showing potential as a therapeutic tool for obesity and metabolic syndrome.