This morning I woke up and weighed in at 168 lbs (at 6 feet tall). This is the same weight I've been at for most of my adult life. In fact, it is the same I weighed when I graduated high school 20 years ago (are there any awards for this?). However, as I wrote about years ago, my body composition doesn't seem to be quite the same as it was then.
Looking back, there are some other differences between now and then. First, like many 18-year olds, I paid no attention to my eating back then. I ate whatever was around. Now I take tremendous care in what I eat. Yet even with this increased effort, I still have the downward shift in body composition.
Second, I seemed to have more "miscellaneous muscle" back then. Looking back at a high school picture, I seemed to have more muscle in the shoulders and trapezius muscles, even though I didn't lift weights at the time. Now I lift weights, but this by itself doesn't seem enough to regain this miscellaneous muscle.
All this points to bigger factors, like hormones, in driving body composition. Hormones are obviously at full-blast when you are 18. As you get older, testosterone declines. Then it feels like you are putting more and more effort into diet and exercise, but that you keep getting less and less out of it.
I've got a couple posts coming up on using alternate methods to improve body composition.