While cannabis alters the functions of neurobiological circuits controlling appetite, its effect on weight gain is complex since several factors appear to be involved, says Didier Jutras-Aswad, University of Montreal professor and researcher at the CHUM Research Centre. “It is known – and often reported by users – that cannabis causes temporary increase in appetite. As to whether it actually causes weight gain in the long term, the available data is limited. The question is all the more difficult to answer since many other factors can influence weight. For instance, cannabis use may be associated with cigarette smoking, which also alters appetite, and many effects of cannabis vary by gender and level of use. For this study, we wanted to better understand the association between cannabis and weight gain by paying particular attention to these factors. The main finding of our study shows that long-term cannabis use indeed influences weight gain. But above all, we noted that certain factors drastically modify this effect, including gender, level of use, and concomitant cigarette smoking."