An underactive thyroid lowers the metabolic rate and makes it very difficult to lose weight. It does not seem like a vain question, it is a matter of good health. Of course, you can watch your diet and get in some good exercise, but this is made more difficult during pregnancy. Depending on just how hypo you are, it can be almost impractical to prevent weight gain, without thyroid med. If you have thyroid test results, post them and you will get some good opinions from experienced forum members. Another way that I believe in, is to check your temperature several times a day for several days and average the results and compare to normal of 98.6.
Yeah but here's the thing your body is a chemistery set and the reason you gain weight is because your body is reacting to PH levels and other levels that or off. Consider this if you gain weight around your stomach would you think its because your producing to much cortisol? No,..your not trained to be thinking that! Your adrenal gland has a mechanism that is Flight or Fight and it will secrete mucho hormones albiet tire. If, you crave a certain food lets say potato well that to me equals potassium. learn your body's eco-system and weight will never factor in.