Weight Gain

You'd have to ask your doctor. If your metabolism is that fast, it is just going to keep burning everything you eat up. Not sure why they put you on an appetite stimulant and not something to slow down the thyroid. Are you also exercising? If so. . . STOP!

I gain weight quickly when I eat a cup of rice 3x a day and lose quickly if I don't.

I think it is still best to eat a well-balanced diet and do some exercises.

maybe your metabolism will change when you're much older. or maybe as mentioned it's your thyroid. is being underweight causing you any problems?

I wish I could help you out. I am envious that you do not gain much weight. I look at food and gain. I must say in the summer I have less on me because I am not that hungry and want drink a lot. I have been on diets but know they are not the answer. I joined overeaters anonymous a long time ago and learned what I have to do. I have to give up things I love to eat that are not good for me like sweets, but, lately I do not eat that much of it. I have to learn to exercise more too. Why don't I do it because I get caught up in other things. Sorry, I cannot help you. I hope you find someone that can.

But why you want to gain weight?? Are you healthy?? If you feel healthy then no need to worry much about it. My only suggestion is eat healthy food at right time. Dont skip breakfast. Dont think to gain weight by consuming fatty foods which would invite other diseases. We need fat protein carbohydrate in balanced. You have a good metabolism..Stay healthy!!