I don't think menopause automatically sentences someone to be fat.
My sister took up competitive rowing in her early 50s, and you should see her rock-hard, whippet-like body. She comments that she is in the best shape of her life.
Other lifestyle changes in the menopausal years can be as much to blame as menopause itself, for weight gain. But it never hurts to attack the problem with some kind of exercise.
Also not every women is the same. There are going to be women who have no trouble at all. Stay thin, don't get depressed, just ease on through it. I call them SO LUCKY! Depends on your own body, YOUR Hormones.
40 is a little young to start Menopause, but not unheard of, it can happen. I started @ 49, for 1 year, I would bleed for 7 weeks, then it stop, started, did that for a year. I have not had a period for 2 yrs now. I started gaining weight a little weight in my mid section, I also got very depressed. I'm not a depressed type, always happy, not moody. I had to go on Prempro, it took 2 weeks, I was better. I am having trouble with words, simple words, I forget how to spell them, or even say them. I am really frustrated with that. But I'm going to get a Natural one, Hormones and then ween myself of the prempro. That can cause Cancer . Hope that answer your ?