“Has something happened — a change in relationship or job? Has that affected the times that you’re eating, how and what you’re eating, and who you’re eating with? Those changes in eating nutritionally can affect your weight,” Weiner said. “If you used to eat with other people, you maybe had more vegetables. Alone, you may be eating less healthy foods.”
If you were very active in your younger years, you may have had some injuries. Like a spicy pepperoni pizza does after dinner, those injuries from your carefree days can come back to haunt you. These ghosts of injuries past show up in the form of early arthritis, bone spurs, tighter muscles, pinched nerves, etc. After our 30’s, new injuries also take longer heal. No wonder we slow down.
There appears to be a connection between estrogen and body weight regulation. With lower estrogen levels, lab animals tend to eat more and be less physically active. Levels that are too high or too low appear to lead to fat storage. And, lower estrogen levels may also slow down your metabolic rate (the speed at your body converts stored energy into working energy).
Guys often wonder whether a dip in testosterone is at the root of their weight gain, says Dr. Stanford. "When men develop overweight and obesity, they tend to have a drop in testosterone that leads to a drop in energy and more retention of adipose tissue,” she says. The excess adipose tissue drives testosterone down. But taking testosterone isn’t usually the answer. “That’s not the underlying problem. Once we normalize the weight, the testosterone normalizes," she explains.
When you were young, you probably didn't spend too much time thinking about preparing your body for the future. In your teens and twenties, you're in peak condition and it's the perfect time to start exercising. Cut to 20 years later and, if you didn't start exercising, you probably wish you had since there's something we all start to experience in our 40's—weight gain.