Hello dear, Weight gain is one of the feature of hypothyroidism. In this, there is decreased production of thyroid hormones resulting in decreased body metabolism. Eltroxin, a substitute for physiological thyroxin, helps in regulating the metabolic process. So, along with intake of eltroxin, a low calorie low fat diet and regular exercise should be followed such as: 1. Avoid eating white breads, rice and pasta. They have high calories and increases the blood sugar level. 2. It is better to have complex carbohydrates such as whole wheat bread, oatmeal and brown rice. 3. Consume low fat versions of milk and cheese and avoid oily foods. 4. Have a diet rich in low calorie protein foods such as egg whites, skinless chicken, fish, etc. 5. It is better to avoid soft drinks and fruit juices which are rich in calories. Instead, drink large amount of water (about 6 to 8 glasses) throughout the day. 6. Dietary fiber such as whole grains, vegetables, fruits, and nuts can also be included in the diet. If you still find any difficulty, kindly repeat your Thyroid profile investigations & consult your treating physician. Wishing you a Good Health. Thanks & take care.