Hey there!
Just wanted to add my 2 cents!!
I am a thyroid cancer survivor and the girls I work with call me the "thyroid queen" because I know so much about thyroid function, thyroid meds, etc.!
I just want to say that those who stressed how important taking your medication is are 100% right! Once you develop hypothyroidism (low functioning/sluggish thyroid) you generally have to take medication for the rest of your life (there may be very rare cases where you can stop, but generally the rule is it's a lifelong med).
I think the 1 pound is totally a coincidence - it takes about 4-6 weeks for the medication to take it's full effect (thus your doc will give you a lab slip to do in 6 weeks each time he adjusts your medication).
Your thyroid produces hormones that EVERY cell in your body need to function properly! It's extremely important!
There are basically 2 different types of thyroid medication:
Synthetic (i.e. "Synthroid")
Or Natural (Armour Thyroid, Westhroid, Nature-Throid --- it's "natural" because it's made from porcine thyroid glands aka "desiccated thyroid")
After I had my thyroid removed I was on Synthroid for a few months which works for many people, but I was not one of them, I continued to have depression/anxiety, memory loss, fatigue, excessive weight gain, dry skin, cold intolerance, etc. so I was switched to Armour Thyroid and all my symptoms are gone (except for the weight problem, but that was an issue before my thyroid cancer, and I did lose 30 lbs after starting Armour) - I've been on it for 2 years and my levels have stayed very consistent.
Anyway, my point is that if after being on Synthroid for awhile if you don't feel an improvement do some research on natural thyroid medication and see if it might be right for you...
One more thing, you said your TSH was 4. something? After I had my thyroid removed they didn't give me any medication because of this special kind of radiation treatment I had and my TSH got up to FIFTY (the higher the number the more hypothyroid you are). I felt like an 80 year old! It was horrible!
Anyway, I could go on and on about this subject all day LOL - if you have any other questions let me know!