You're overwhelmed with stress.
Researchers at the University of Alabama found that volunteers asked to do stressful tasks like listening to irritating noises and viewing unpleasant pictures swallowed three times more frequently than those who engaged in relaxation exercises. The problem? Repeated swallowing sucks excess air into the stomach and the intestines, causing the abdomen to expand. What's more, stress can make your intestines sensitive enough that you feel extra-bloated even when you're just passing your standard 700 milliliters of gas (it can also make you burp). Relax your mind and slow your swallowing with 10 minutes of progressive muscle relaxation or meditation.