In addition with the other responses to this, people who smoke, drink, or do drugs generally aren't snooty about it (unless they're in high school and feel cool), and they CERTAINLY don't claim it's healthy for them, despite the weight loss benefits associated with all three.
"Hey, I've lost ten pounds since I started smoking! You should try it!"
"I've been drinking heavily lately, so I puke a lot! I've lost tons of weight by only partially digesting my food! Best diet ever!"