I think about half a stone around the waist is fairly inevitable, hormones change our shape.
Not it's not.
That's a LOT of abdominal/visceral fat to carry and very bad for health.
Women's shape does change (although maybe not if on HRT) but not in such a drastic way as half a stone. Weight put on tends to settle on the waist but that's weight put on. It's not inevitable to gain weight.
It's worth googling Zoe and Prof Tim Spector. He believes that everyone loses or gains weight in a very individual way according to gut health and gut microbes. Some people lose weight on a high fat/ low card regime, others do better on a medium carb and low fat.
What is clear is that gut microbes are very important and he suggests that we all eat at least 30 different plants a week. (You can't count the same one twice!)
Plants includes all veg and fruit, as well as herbs and spices, and wholegrain cereals/pulses.
Low carb works for some people- that's no more than 50gms a day max- whereas for other people they feel starving and can't keep it up long term.
I'm the same weight as I was in my 20s but I know I am carrying a couple of pounds more fat on my tummy and have lost muscle off my thighs. It's an ongoing battle! For me, low carb works, which means I only eat carbs once a day or twice in very small amounts.
You've just got to work out what works for you!
Exercise doesn't always cut it and you may be eating more than you need, in spite of it being healthy food.