Perhaps! But this is not what you should be concerning yourself about. To go to basics, there are two different problems a person can have with their thyroid hormone production as a result of disorders in their system. Either you can have RAISED blood levels from your thyroid hormones or REDUCED blood levels of your thyroid hormone.

Overproduction of your thyroid hormone known medically as "hypERthyroidism" does cause sweating and diarrhoea as well as weight LOSS. But insufficient thyroid production known as "hypOthyroidism" -(my capitals are to avoid you confusing the two) causes weight GAIN!

But what doctors should be trying to do if they are doing their job properly is try to regulate what happens inside you until they get it right. and that is, a bit like balancing a scale. When two much weight is on left side of the scale, more weights have to be put on the right side of the scale to make it balance again, and if they inadvertently put a little too much that again has to be rebalanced. That is more or less what they should try to do inside you. And as part of this, when you have hyperthyroidism, it is likely you would be prescribed synthetic thyroid hormone preparations levothyroxine and liothyronine. But the doctors presumably know because too sudden an increase in a person's thyroid hormone level can strain some people's hearts, these drugs are usually prescribed in low doses that are GRADUALLY increased? That is probably why you have apparently had a bit of both symptoms during your treatment, although of course I do not know your precise circumstances.

So while your weight is likely to go down when you have hyperthyroidism and go up when you have hypothyroidism because of feedback system in you involving your pituitary gland and hypothalamus. So the long term aim of your treatment should be to get your bloodstream just right. This is important for you not for any reason to do with your weight but because if the blood levels of the triodothyronine and thyroxine produced by your thyroid is not kept within correct limits you either suffer from the problems caused by hyperthyroidism OR the problems caused by you having hypoithyroidis.

So that is why the primary consideration for you to become healthy is that you do have regular visits to the doctor and have blood tests to monitor the exact levels of the four different thyroid hormones being produced by your thyroid gland. Your doctors are not primarily addressing the issue of you being too heavy or not heavy enough because there are far more important problems for your health if you have either hypothyroidism or hyperthyroidism

When they eventually succeed in getting the right balance you are then healthy and your weight should hopefully then neither increase nor decrease. But until they get the balance right, depending on the dosage of corrective action your weight will temporarily fluctuate. so just do not let that concern you.