Their researchers, reported in JCI, have discovered a particular form of a gene, previously linked to obesity, known as FTO. FTO is a gene that is traced to increased cravings for high-fat foods. In addition to obesity-related studies and various tests, scientists have also discovered recent genes that have been linked to obesity. The first gene related to obesity is leptin. Leptin is considered the "obesity hormone", leptin is produced by fat cells and is the thermostat for the body's energy needs. In each individual's own leptin input, if for any reason leptin levels drop below the correct amount, the brain understands that the body is starving and needs more calories, if maintained at or above the correct amount, the brain knows that it doesn't need more food. Obese users have higher blood leptin levels. However, researchers are confident that obese people are not getting the signal to stop eating. Another gene is ghrelin. Ghrelin is the gene that is the appetite hormone, making food more desirable. Studies have shown that sleep-deprived people have increased levels of ghrelin. The last gene supposedly related to obesity is neuropeptide Y. Neuropeptide Y triggers eating by manipulating appetite, resulting in mood swings and high levels of stress (Health). According to the source of bariatric surgery, obesity