Good morning, After you have had such a major surgery there are disruptions in how you eat, what you can eat, and, most places assign a colectomy patient with a dietitian to work with. The Ankylosing Spondilitis is not related to your colectomy, but what I hear you saying is you have two prominent issues you are trying to deal with. It seems overwhelming and no one is listening? You want an explanation for the weight gain. I can list possibilities since you are not my patient and I have not been able to do a full assessment: your activity has declined since the surgery; imperative to exercise 150 minutes per week (walking briskly is a good way to start out); follow a balanced but strict calorie restricted diet, I usually recommend 1200 calories per day. Figure your protein needs as .8 g per kg body weight. No sugar, no carbonation, - you already know about your surgical guidelines as far as gassey vegetables and rinsing your beans to get the gassey chemicals out? If not, this is what you do with lentils, red beans, etc. If they are canned, drain and rinse well. If soaking, soak all day, then drain all of the water. Then fill and bring to boil and drain again. Then by the next time you fill with water they should be ready for cooking Next, include thermogenic aides until weight loss is going along at a good clip: green tea, caffeine, Tumeric in cooking; blueberries; vitamin D 1000 IU ,1200 mg. calcium citrate from diet or supplement; Human Studies have shown, but recommendation for not available because of few human studies, that 150 mg of resveratrol (purity is important) will raise your metabolism and help with weight loss. Resveratrol is the compound found to be responsible for the lowered cardiac death rates in the Red Wine Studies. I hope this has helped a bit. If you have more specific questions, please feel free to write back. If you give ma a location in US or India, I can refer you to a Dietitian in your area. She will want a food diary: date,time, amount, food, symptoms. It has been a pleasure assisting you. Kathryn Shattler, MS,RDN