For me nothing happened weight-wise the first 2 weeks on the PB. Then I lost about 2 lbs. a week at a steady clip. I think I was fairly low carb with little fruit and no starches.
I was also doing the exercise portion as well.
I'd say he either goes heavy, by changing his lifestyle to the PB or he goes home. Trying to lose that much blubber in 10 weeks would just be a brutal crash diet where he'll shed both lean muscle and bone mass as well as fat, the latter of which will be packed on as soon as he resumes his old lifestyle.