I've been on letrozole for four years without any weight gain. I was at my lowest weight since college when I started it and weigh the same now. Independently of breast cancer diagnosis, I spent the last decade or so increasing exercise and decreasing calories a very small amount at a time. Many people wouldn't find such a slow system rewarding and I'm not recommending it, but I can maintain it--and no effects from the letrozole. Wishing you the best with the aromatase inhibitors.