No, you are not imagining it. Your body composition begins to change at peri-menopause, and those changes persist throughout the rest of your life. It's not your "fault," and there is no more reason to be alarmed than when your body underwent changes during puberty. Menopause is a normal process for women. It's not a disorder, and it doesn't need to be fixed. You just need to learn how to work with the changes.
The initial reaction of many women to weight gain is to restrict calories, and many turn to the latest diet fad. Restricting calories likely will produce short term results. But in the long term, the weight comes back. In addition, particularly if you are an active woman, you are probably undereating, not overeating - this makes the problem worse!
Studies show that many women experience low energy availability as a result of a net calorie deficit. Undereating will cause your body to store fat...it thinks you're starving. And undereating will make you cranky, sluggish, brain foggy, and decreases your energy during exercise. Since the lower estrogen levels of menopausal women also produce those symptoms, it's easy to see how undereating only makes things worse. (And it might explain why your symptoms are not resolved even with menopause hormone therapy (MHT).)
So, what's a woman to do? A few thing will definitely help:
Eat throughout the day, 3-4 meals including before and within 30 minutes after exercising.
Make sure you get enough protein - plant protein like beans and tofu, eggs, cottage cheese, yogurt, and lean meats and fishes are the best choices. (I confess that it requires effort to eat protein 3-4x/day so supplement with a high quality - NSF or USP certification - whey or casein protein powder if you need.)
Eat lots of fibrous fruits and vegetables. They will make you feel fuller, will increase your gut health. Moreover, no one ever became obese because they ate too many fruits and vegetables.
Don't cut out carbohydrates. Lots of fad diets (think keto) restrict carbohydrates but those are required by your body for brain and muscle function.
Consider a food tracking app to hold yourself accountable for what you're actually putting inside your body. I've had personal success with the Weight Watchers app, which has settings for losing weight and healthy eating, as well as healthy recipes and shopping lists. .
Speaking of being held accountable, enlist a friend to join you. Studies show that if someone asks you regularly about your habits, it will have a positive impact.
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