I have come across the word "leptin" a lot recently and instead of just skimming over it and knowing it is vaguely related to weight, I thought I'd do a bit more research.
Leptin (from the Greek word leptos meaning thin) is a hormone that helps control appetite and metabolism. In a normal weight person, when body fat increases, leptin levels rise which signal the brain that it needs to speed up metabolism and decrease appetite. According to Leo Galland, M.D., author of The Fat Resistance Diet, when folks are overweight the leptin message gets lost and the body cannot regulate its fat stores.
New research indicates that inflammation, a condition in which your immune system is kicked into overdrive, may lead to weight gain and make losing more difficult. Doctors think inflammation interferes with leptin production. So from a nutritional perspective you should eat inflammation fighting foods that are high in omega-3 fatty acids.
Simply put, leptin is part of the complicated chemical process that helps regulate weight.