No Way, Dude!

Marijuana Slims? Why Pot Smokers Are Less Obese

The headline is misleading; they don't really know why but they observe that pot heads are, on average,  skinnier than non-pot heads:

Researchers analyzed data from two large national surveys of the American population, which together included some 52,000 participants. In the first survey, they found that 22% of those who did not smoke marijuana were obese, compared with just 14% of the regular marijuana smokers. The second survey found that 25% of nonsmokers were obese, compared with 17% of regular cannabis users.

But before you go on the pot weight reduction plan (recommended by Northern California and Mexican growers everywhere) be aware that the relationship might not be causal in the usual sense:

Many other factors could account for the connection. For example, some research finds that highly religious people are less likely to take drugs, but more likely to be obese — perhaps because they're substituting one compulsive behavior (overeating) for the other (smoking marijuana). So, some of the obese people in the national surveys may be religious folk, who might otherwise be heavy marijuana smokers, but are eating too much instead. That could make it look like marijuana is slimming.

Also consider that one of the most popular uses of medical marijuana is to stimulate appetite in people with cancer, AIDS or other diseases. Such patients are significantly less likely to be obese than the general population — so in this case, weight loss would precede or prompt the marijuana smoking.

They allegedly controlled for health so I'm not sure the second one is consistent with the study.  The first seems a bit of stretch, but stranger statistical associations have happened.