abdominal cramps when dieting

My husband gets this sudden severe abdominal spasm on his sides a few inches above waist area and usually reoccur at rest and last for several minutes. This had never happenened to him before. But he told me he usually gets abdominal cramplike pain on his Right side when he diets and exercise. My husband you see is overweight and is trying to lose weight. He skips meal sometimes and has BM 3-4x a day. He has gout and asthma. He's a smoker and drinks in a minimum at night. When he's in pain he has the habit of taking 4 tabs ES Tylenol once or twice a day. But I just couldn't understand why that much pain and the pain is somehow localized on the sides. Stretching seems to relieve the pain a bit. I just could not explain why.