I'm 52 and have been very active over the past five years (CrossFit until my ankle gave out, rowing at home, personal trainer, cycling), but couldn't keep the weight down, though up until my mid/late 40s, I could eat anything I wanted whenever I wanted, and was a skinny mini. I guess getting the idea that those days are gone didn't sink into my thick skull. I always joked that I was the fittest fat person I know, but it's not funny anymore. I'm on a very strict diet (very low cal paleo) that I won't be able to maintain and be healthy when my ankle is healed enough to start doing some serious mileage on my bike again, but since the weight is coming off quite easily, I can't even pretend that all my weight issues aren't diet related. I've already lost 23 pounds, and am now starting to get how quickly I could put it back on if I'm not very careful. Ugh.