As one gets older, metabolism slows down and that is what makes you fat. The trick to staying in shape in old age is to keep your metabolism rate higher. Only 1 way you can do that. Regular exercise. I was overweight from my 30’s into my late 50’s. Then I made a lifestyle change and took up regular exercise. Now at age 82 I still have the same size suit as at age 25. There are multitude of side benefits to regular exercise after Medicare age. Such as better resistance to respiratory diseases, much better balance which avoids falls, better bone density, and lots of energy. I rarely see anyone over age 70 in the gym.
Yep, and my wife and I keep each other in check. We both like keeping the excess weight off. She quit soda pop about 10 yrs ago (a pop has been rare for me for 40+ yrs). We avoid deep fried anything most if the time.
We don’t go to a gym. We have a couple of cheap machines: a rowing one, and an old nordic track ski machine. We do some exercises in the family room, and ride bikes some.
That, AND being less active. It's both.
Especially these days when often the only activity people do is stare at a screen.