Stupid.
Fat people are nothing new. The military has ways of dealing with them without slowing everyone down. In the Marines, people who couldn't keep up physically were dropped out of their platoon and into Physical Conditioning (better known as the Pork Chop Platoon). I'm sure the other branches have similar programs.
Also, even if you come out of Basic meeting only the basic minimum of standards for military service, so what? That's what basic is supposed to do, which is why they call it that. Even in the Marines, you aren't expected to be combat ready out of boot camp. You still have to go to school for that.
And that's my final point. A modern military requires something like 4 non-combat personel for every combat troop. If a guy can't handle the physical burdens of combat training, exchange him for one who can who isnt in a combat MOS. But then, the military doesn't need me to tell it to do this, it does it all the time.
Oh, wait. One more thing. You have to remember that fat people aren't necessarily lazy. Young people, at least, generally get that way not because they avoid physical activity, but because they don't have to do it or they enjoy other activities more. When put in a pressure situation such as boot camp, most will rise to the challenge.
Those who do not don't need to be there in the first place.
The kid, maybe 12-14 years of age, living in war torn Iraq, wearing pyjamas that an 8 year old girl would wear in the western world, but he still is showing strength. I have respect for that.