"Proven to have no benefit" in this case only means that most people won't lose weight after being told to. A minority will though, so doctors refusing to tell

"Proven to have no benefit" in this case only means that most people won't lose weight after being told to. A minority will though, so doctors refusing to tell fat people to lose weight is a disservice to the few who stand a chance of making it. The rest should either be signed up for surgery, drugs, or written off as lost causes.