weight gain isn't the only factor to consider. However, with that said, if your thyroid isnt within range within 90 days, they might have to increase your dose. If they were to increase your dose, your weight (at best) will stabilize, and might even start losing weight. If you just gained 3 inches to your belly and no actual weight gain, it might be something else not entirely related to your thyroid. Usually, that kind of gain is due to water retention, or some kind of electrolyte imbalance. a full metabolic lab test will answer that.
Problem with thyroid, is that the thyroid itself doesn't absorb alot of thyroid hormone, so that is why they will have you go back again in 90 days to do labs to see where you are. Also same reason as to why you have to take that medication on a empty stomach. So moral of the story, give it some time at least 90 days, the meds might not have kicked in fully yet.
getting your thyroid back within range is worth it. Medications are cheap, and its relatively easy to manage. Just remember if you are not "feeling yourself..(tired, fatigue or irritable or can't sleep) or if you gain or lose weight to fast, or nails or brittle or skin is dry, or hair is dry, or you constipated or having diarrhea..its your thyroid. Basically, if you aint yourself...go get your thyroid checked out.
