My TSH level was 43 when they discovered I was hypothiroid. I was gaining weight also but after a year of being on Levoxyl I've finally got my weight under control and my TSH level is down to 2.6. Still feel tired and crappy but I am a lot better than I was. Think it all depends on age too. I'm 54 and I think hormones are affecting the way I feel too. If your TSH level is 18 you need to be on Levoxyl. You'll start feeling much better in 3-4 months. Take care now.