Leptin Leptin and ghrelin are two hormones that have been recognized to have a major influence on energy balance. Leptin is a mediator of long-term regulation of energy balance, suppressing food intake and thereby inducing weight loss. Ghrelin on the other hand is a fast-acting peptide/hormone, seemingly playing a role in hunger. As a growing number of people suffer from obesity, understanding the mechanisms by which various hormones and neurotransmitters have influence on e