I don’t think it has anything to do with them. For the 3 months before I started on ATDs and beta blockers, I didn’t lose any weight – but I know it’s because I ate like a horse. After the ATDs started working (a few weeks later), I wasn’t cutting back on food and so I started to gain weight. The ATDs slow the thyroid down, and hence, your metabolism. I am back to fighting my lifelong battle with weight, but for those few months it was great to eat,eat,eat and not gain!