Scientists discovered another piece to the obesity epidemic puzzle. They've identified how a mutation in a single gene can block the body’s message to “stop eating.” In this study, mice with the mutation ate 80% more food than normal. The gene has been studied before, but this is the first time that researchers could pinpoint how the mutation causes overeating and obesity. After eating, hormones in your body tell your brain that you are full. In the mice with the mutation, this message doesn’t reach the right part of the brain, leading to severe overeating and obesity. The mutation messes with the communication between neurons in the brain, which means that the signals from the hormones—such as insulin and leptin—are ineffective. In the end, eating doesn’t change the appetite, so there’s no sense of being full. Healthy eating and exercise are still important components of maintaining a healthy weight, but researchers noted that 40% to 70% of weight differences between people is caused by genetics. The current study was carried out in mice, so future research will need to be done to confirm that the gene functions the same way in humans. This gene, however, has been previously linked to obesity in humans. For people with the mutation, this research may someday lead to new ways to control their weight by helping the “I’m full” signal reach its destination.