Research by Yale University shows that women with the biggest bellies also suffered with the most amount of stress, which is thought to be due to chronically elevated levels of fat-storage hormone cortisol. Adopt stress reduction techniques to reduce negative emotions, which increase cortisol, such as anger, anxiety, fear and stress. Also, learn how to nip stress in the bud. Stress is okay; most of us thrive on it, but only for a very short time. Drawn out, continuous stress is different, damaging and unhealthy.