Bad sleeping habits You would gain weigh either if you don’t get enough sleep or take too much sleep. Weight gain is from biochemical reaction and your habit of staying awake late night eating snacks. Stressed Stress releases cortisol in your body which increases appetite. Another reason to gain weight The Polycystic Ovary Syndrome Women at the childbearing age would have this hormonal problem. The growth of cysts and hormonal imbalance adds to weight gain. Hypothyroidism You underactive thyroid gland produces less thyroid hormone and slows your metabolism, which in turn gains weight Steroids Prednisone for example increases appetite and retains salt. Combined with poor food choices you would put on weight. Antidepressant’s long term effect Certain antidepressants can cause weight gain on a long term use. Prescription Drugs too BP medications, diabetes pills etc could add to weight gain too. Crushing Syndrome Crushing syndrome is a condition where your body produces too much cortisol. This causes weight gain in addition to many other health problems