1. BMI is nonsense. I was once considered "obese" according to BMI. I was 6'4" 255 or something, and my body fat was less than 10%. I wasn't in the best shape of my life or anything (well, cardio-wise... I was a big, strong guy though), but I was hardly obese.
2. You should not be obese. If you are, what are you thinking? Take care of that ****. At the ER where I work, I see people who come in every day who would not be in that position if they had taken care of themselves when they were younger.
3. Maybe its the personal trainer/kinesiology-degree-holder in me, but typically, I consider obesity to be a sign of irresponsibility and laziness. If I was on an adcom, I would definitely wonder what the hell was wrong with someone who is in their early-20's and in that condition. At what point does it occur to you that maybe you shouldn't eat as much, or maybe you should be a little more active? Is it when you can't see your junk anymore? When you can't walk up a flight of stairs? The onset of diabetes? Your first BKA? Your second BKA? Obviously, there are exceptions, but if I was on an adcom, I would want to know what the problem was if I interviewed someone who had allowed themselves to get like that.
4. For those of you who are obese, or close to it... don't let it get out of hand. Take care if it while you're still young, and your body can handle the stress a little better. You'll be happy you did when you're 50 and can still walk comfortably.