Yup. As I said, I run three days a week (10 miles total), weight train three days a week (four hours total), eat six small meals a day of chicken, soy, vegetables, whole wheat, sometimes potatoes, and occasional a protein supplement after a really hard workout. Drink only water.
You'd think I would drop weight like a bad religion, but at best (which means when I am my heaviest due to an "extended" vacation or holiday... 215 lbs. or so) I can drop one to two pounds a week. That's pretty fast, but it levels off whenever I get down to 195 or so.
I can't imagine how much more I'd have to run, or starve myself, to drop any more weight than that. And my gut won't ever completely dissapear... it just goes into hibernation for a while and isn't visible for a short time (until the next "vacation").
I think it is metabolism. I was always thin, and when younger I could eat as much as often as I wanted too, and still seemingly lose weight. Now one week of eating fast food takes two or three weeks to undo the damage. And it's anything but easy. I run and work and starve my ass off just to "maintain" a decent body fat percentage.
thank god for puberty taxing my body with the extra height and thus drainin me fat off like butter, grew to 5 11 in 4 yrs, never grew much after 17-18, got a spinal curvature, stand between 5 10 and 5 11 depending on my spine 
