FACT: If you're trying to lose weight and you're not, you're not in a calorie deficit
You may have read somewhere that it's because of hormones, or genetics, or your age, or metabolism.
While these can play a small part, the majority of your loss or gain will be based off of the calories you eat.
Studies have concluded vast underreporting of calorie intake
So, a little tough love here. If you're "eating healthy" or eating "pretty good" and you're still gaining weight (and you don't want to be gaining weight) - you have to track food! You have to learn how to eyeball quantities and stick to it.
You learned how to read, write, drive a car, open a bank account, rent or buy a home, and many other things. You CAN learn how to control nutrition intake to benefit your health and longevity.
I teach people how to do this. It's my mission. I'm sorry they don't teach this in school (they should) - but it is a basic human skill!
The food industry is NOT your friend. They want your money, not your health. Cheaper processed foods are more expensive, health wise, in the long run.
It's the old saying, "Cheap now, expensive later."
YOU are worth it.
YOU should be your biggest investment, not some fancy car or faux-luxury lifestyle - YOU.