I heard a report on NPR that a typical American adult was at a healthy weight when they were in their twenties but then put on an average of just 2 pounds per year (which doesn't sound like much) until they wake up one day in their fifties and find they are seriously obese.
That's me! The attached plot shows all the weights (pounds) I have records for since I graduated high school (1975). You'll see that I was 143 in college and reached a peak of 216 a little over three years ago.
I tried several times in the interim to lose weight and each time put it all back on. Then I finally got disgusted with myself and totally changed my attitude to eating and exercise. I lost 66 pounds! Yes, it can be done!
But then I did exactly what I said I wouldn't do and what I have seen every other person do who has lost lots of weight: I've been putting it back on.
You can see I've regained nearly half of what I had lost. I've seen one guy who must have lost 100 pounds (he was my hero!) turn around and put it all back on and more in about a year. That must be heart wrenching. Aside from a (temporary?) knee issue that limits the kinds of exercises I can do, I have no reasons I can give for my own problems. I'm currently back on the way down but who knows for how long.
My only advice is (1) take a look at that apparently typical graph and ask yourself if it resembles you, (2) look and feel your body
and honestly ask yourself if you think you're healthy, and if not then (3) do something about it (I don't know what or how because I clearly don't have the complete answer). I wish you luck!