Stomach growling? Thank ghrelin. Produced in the stomach, ghrelin cues the brain that you're hungry. After you eat, leptin swoops in to tell the brain you're full. If these two hormones fall out of sync, you may lose the ability to recognize when your body is satiated and overeat as a result.
What You Can Do
Try your best to get a full night's sleep: A Stanford University study found that habitual sleep restriction (five hours a night as opposed to eight) raised a person's ghrelin levels by nearly 15 percent, lowered leptin levels by 15.5 percent, and was directly associated with increased body weight. Other research has shown that exercise and stress reduction may help keep ghrelin levels in check.