True, being overweight (or obese) is a risk in its own right, and maybe even greater.
I started in Nov 2007 at just under 300 pounds; was on Dukan really strictly until June 2008; then moved to the UK and have been mostly maintaining (phase 3) and occasionally going back to cruise briefly, then back to maintaining; then... slipped. Yeah, shame but now that it is a fact I am back to Dukan for good.
P.S. Right, why would they call it a crash diet if it is a life-long plan, in a way - considering the life style changes one has to accept and principles to stick to...