Having a thyroid problem doesn't necessarily correlate to weight problems. Kind of depends on who you talk to. You don't say how bad your problem is -- is your thyroid still working and is just low, in which case you might be able to fix it by eating iodine rich foods such as iodine, or is the thyroid not functional anymore, as with Hashimoto's? Are you on synthetic hormones for it? Because if you can fix it through diet, it ceases to be an issue. If you have to take meds, it will stop working forever and will forever be an issue, because if your meds aren't calculated correctly weight can become an issue again. Depending on who you talk to, of course (endocrinologists will often say no evidence exists tying thyroid to weight, while almost everyone who has the problem does). As for diet, it's not different for someone with thyroid problems than for anyone else. You need to exercise so you burn off what you eat, and need to eat a balanced diet with emphasis on antioxidant rich vegetables. You need to avoid foods that are too high in fat and sugar and eat foods high on the glycemic index in moderation, such as foods made with white flour. And move more than you eat.