I've been on estrogen only HRT for ~15 years following a hysterectomy. I lost 16.5 lbs the first 3 months on Atkins and it took a little over a year to lose the next 10 (I've since gained back a bit after a stressful past 6 months. However, I'm also right at the normal BMI point, where every pound can be a struggle. I think that is more of an impact on my weight loss than HRT.

In short, I think it is important to get your hormones balanced and let the weight loss be secondary. Post-menopausal women generally gain some weight and change proportions. I think it is probably going to help more than hurt for you have have your hormones normalized.