I started HRT earlier this year. Although I was slim everywhere, but round my waist. ( what waist? Little difference between waist and hips). My bmi was 22. But the gynaecologist warned me I was at as great a risk from diabetes type 2 as people more obviously overweight. I have a very strong family history of type 2 diabetes. I had slightly raised glucose levels, cholesterol and BP levels. So I followed advice and cut all sugars down and stopped snacking. I lost a stone and a half pretty quickly. Probably too quickly. Swapped diabetes for gall stones, though the doctor says that has no bearing on it. As my weight is still falling, I have had naughty things to eat again, but not like I did.
I think my story shows you can lose weight, HRT or not. Be honest, what are you eating and how big are your portions. Do you go out for walk, cycling etc.? By the way I have a waist, though I still have a band of fat around my middle, but I can hide it now.