Think weed munchies will take a toll on your waistline? It's not that simple. According to the results of a study published in the journal Heath Economics on Nov. 25, states that implemented laws allowing medical marijuana saw a reduction in the likelihood of being overweight.

"The enforcement of [medical marijuana laws is] associated with a 2% to 6% decline in the probability of obesity," researchers from the San Diego State University and Cornell wrote.

"These findings are consistent with the hypothesis that MMLs may be more likely to induce marijuana use for health-related reasons among older individuals," they wrote, "and cause substitution toward lower-calorie recreational 'highs' among younger individuals."

The findings also showed places that embraced medical weed had a roughly $58 to $115 reduction in per-person costs of obesity-related medical expenses. "What we know, and have strong evidence for, is that these policies do have significant effects on health outcomes," study co-author Jeffrey Swigert told Mic.

The big surprise: Swigert, a Ph.D. student in Economics at Cornell University, told Mic that the good news came with one significant caveat. It has very little to do with weed itself.

The reason we get the munchies when we're high is that weed can be an appetite stimulant. Naturally, consuming more calories than we burn will make us gain weight. But the benefits occurred in this study because marijuana acted as a substitute for a considerably more dangerous and calorie-rich drug.

That'd be alcohol.

Alcohol! Getty Images

It came a surprise to researchers: Legalizing weed in any capacity tended to replace alcohol in both younger and older populations. Among young people, who are most prone to binge-drinking, the effects could be particularly significant.

"If you think about our ability to cut down on binge-drinking, five beers, that's a lot of calories," said Swigert. Marijuana therapy also caused "increased physical activity" among older cohorts, which was credited with weight reduction in that demographic.

The numbers, however, looked at populations as a whole, and as Swigert pointed out to Mic, any individual who didn't drink would likely pack on the pounds if they developed a sudden appetite for grass. "It very well could be that among some people, those who don't drink, their weight could go up" due to smoking weed, he said.

The good news on the calorie front was also coupled with some of the most potentially significant scientific findings on the drawbacks of marijuana use. According to a study published in Psychological Medicine just two days later, a number of potent weed varietals legally available in some U.S. markets could potentially cause neurologic damage and psychosis later in life.

As weed continues to become more available, and scientific studies become easier to perform legally, it is likely that the industry — and the product — will face increased and more rigorous scientific scrutiny going forward.