Given the infamous "munchies" which occur when smoking marijuana, you might think being a regular smoker would make you gain weight.
Not so, according to University of Miami researchers.
Over a six-year period they studied more than 13,000 people, ranging from heavy users to those who didn't smoke at all.
They found women who smoked marijuana daily had a body mass index 3.1 percent lower than that of non-smokers, and for men it was 2.7 percent lower.
But previous studies contradict this one - their subjects gained weight.
And long-term marijuana use can hurt the immune system and lead to personality changes and reduced sexual capacity.
So don't ditch that gym membership just yet - a weight loss weed diet isn't the answer to that summer body.