Fat is a storage device for lots of stuff. For example, THC (marijuana) builds up in fat cells. Losing weight releases some of that stored up junk. It's not out of the question that some of it would cause you to stink up a storm.
Also, LSD and other drugs. So it must be weird? awesome? for an ex-consumer to try to lose weight.
I can't get the site to load, but if he's using the Atkins diet it's well-known to cause odors due to ketosis.