Oh, 20-somethings. :)

I used to think that way too. When I was 26, I went off to the Netherlands to do my Masters. 18 months later, I sent my graduation pictures to my parents. They asked whose picture I'd just sent! Apparently, some time between 26 and 28, my metabolism shifted gears and my old habits led me to serious weight gain.

If that didn't hammer the point home enough, I had an uncle say to me, without meaning to be malicious, that "I was the fattest person he could ever remember in three generations of the Lee family." :)