[Jimmy Valentine]

Remembering basic training, a lot of people came in heavy and slimed down pretty quickly.

[AZJeep]

Yes,
Moreover:
The military can straighten up the criminals and educate the uneducated.
I remember a a great engineering professor. He dropped out of high school and joined military. They straighten him up and made a PhD professor out of him eventually.
Long time ago - he was one of the greatest professors, I have ever had. Nowadays, they would not taken him in, and he would be probably doing some menial job somewhere.
The military stayed with him though. He was kind of drill sergeant, pretty strict, tattooed and chain smoking.
The snowflakes now would not like him.

[SamAdams76]

In Parris Island, they had the PCP (Physical Conditioning Platoon) for that. This was also called the fatty platoon. I was in it for four weeks but not because I was overweight but because I needed to build up my upper body strength. I could run though, I usually came in first in the free runs.

I would say at least half of those PCP fatties went on to graduate. You can lose weight quickly in Marine boot camp.