Follow low-carbohydrate diet: If you have an underactive thyroid, try to avoid simple carbohydrates and sugars that simply add to your calorie intake. Simple carbohydrates are found in foods such as fruits, milk, milk products, as well as processed and refined sugars such as candy, table sugar, syrups, and soft drinks. Instead, choose complex carbohydrates, which are found in whole grains, legumes, and starchy vegetables. The key to losing weight is eating fewer calories than you burn. Also Read - Unveiling The Radiant Secret: Sesame Seeds' Oil Marvels For Your Skin