My grandparents made a summer visit to our home for many years. In 1967 I was measured at 4 ft 9 inches upon their visit. A year later, I was 6 feet 3/8 inches. My weight was 112 lbs. The growth spurt pushed me from size 6D shoes to 10EE and gave my parents fits trying to keep me in clothing that fit. By the end of 7th grade, I had "bulked up" to 135 lbs. Upon gradation from high school at age 16, I was 155 lbs. During the summer after high school, I managed to get to 180 lbs. That was bad because I was competing in judo and there were weight classes. I was matched against a 250 lb opponent because there was nobody else in a closer weight range. Thankfully I was faster and won the match before the extra weight became a problem. I had to work out 7 days a week for 3 hours per day to pare down to 162 lbs. That was a far more competitive weight.
In 1985 I had cancer. The treatments made it damn hard to keep weight off. If I don't work out every day and watch me food intake, it is very easy to gain weight and living hell to burn it off. Atkins is just about the only thing that works.
A cold virus may be to blame for sudden, unexplained switches from a normal weight to packing on lbs. It's happened a few times with no clear reason. It would be nice to have a better handle on the mechanism and a means to control it.
I am absolutely certain my entire metabolism changed when I contracted pneumonia.
I have to deal with it, but no question, things changed.