I've often heard this amongst other...facts and/or old wives tales.
It takes 30 days for a urine test to turn up negative for metablites,
etc.; however, I would love to see a paper (i.e., peer-reviewed, no
URLs please) that indicate that fat-burning can occur at a rate high
enough to cause an acute, I'll say, intoxication.  I honestly don't
know.

If he's developed a 'tolerance' and was/is 'psychologically' addicted
(I'll leave out the physical part for fear of starting and endless
thread), steer clear of drug therapies and supplements that might
affect neurotransmitter levels.  He's young enough and his brain will
work its way back to an equillibrium without the need for exogenous
librium.  ;)  

Eat healthy, get lots of fresh air and study (perhaps one of the most
mind-numbing exercises known to man).