Study: people using marijuana more than five times per month have a lower body mass index and are more physically active.

FTA:

The study also suggested that people who consume marijuana on a regular basis are more physically activity than those that use it sporadically or not at all. […] A 2013 study published in the American Journal of Medicine found that cannabis consumers have 16 percent lower levels of fasting insulin and 17 percent lower insulin resistance levels than non-users. The research found “significant associations between marijuana use and smaller waist circumferences.”