Reggie Miller -- Warning to NBA: Skinny LeBron James Is a Dangerous LeBron

LeBron James and Carmelo Anthony are gonna wear out opponents even more this season… if diet doc Reggie Miller knows what he's talking about -- and he's a Hall of Famer, so we'll assume he does.

Reggie -- one of the skinniest HOFers ever -- weighed in on the NBA trend of superstars trimming down … and told us LBJ shedding LBs means he won't be carried off the court with cramps anymore.

In fact, Reg explained why 'Melo and LeBron's thin-to-win plan will spell trouble for the NBA … for years to come.

Hard to argue. Reggie Miller knows skinny. And 3s … and Knick-killing.