Marijuana, as everyone knows, causes the munchies. People with the munchies eat a lot of junk food. Junk has a lot of calories. Therefore people who smoke marijuana should gain weight.
A new study calls that bit of common sense into question. At the same time, it suggests cannabis may have promise as a tool in the fight against obesity.
The study was conducted by a team of scientists at San Diego State University and Cornell University, led by economist Joseph Sabia. They examined the answers to health surveys taken from patients across the United States between 1990 and 2012, and they found obesity rates are 2 to 6 percent lower than expected in states that allow medical marijuana.
If that result seems counter-intuitive, it is. Other science has shown, repeatedly, that marijuana is a potent appetite stimulant. That’s one of the main reasons patients with HIV/AIDS or cancer use the drug.
But the researchers concluded that young adults who toke often use marijuana in place of alcohol. Instead of binge drinking on the weekends, they’re smoking up. And since heavy alcohol consumption can pack on considerable weight, these people are staying slim.
That “substitution effect” has been documented in other studies. Among other benefits, it may cut down on opiate addiction, overdoses, and drunk driving deaths. At least one study suggested that states with some degree of legal marijuana tend to have lower highway fatality rates.
Nor is this the first study to specifically conclude that cannabis use leads to weight loss. Previous research found the drug encourages low insulin levels, low levels of insulin resistance, and slimmer waistlines. All three are critical aspects of health for people with diabetes and people at risk of developing diabetes.
The researchers aren’t going so far as to recommend marijuana as a weight loss tool, though it appears to work for many people. They say not enough is known about the full health effects of the drug to use it in place of dieting and exercise.
“We are certainly not arguing that medical marijuana laws are a central tool in the fight against obesity,” Sabia said. “We are arguing that there is an unintended health benefit of these laws in that regard.”
If nothing else, the results give scientists new data in the discussion of whether cannabis helps or hurts the public health, said Brendon Saloner, an assistant professor at the Bloomberg School of Public Health at Johns Hopkins University. And those results are certainly curious.
“If you had asked me before reading this study which direction I would have thought the results would go, I would definitely have thought that the munchies effect would have been the bigger factor here,” Saloner said.
The research still needs focus, he said, and more direct evidence of how marijuana affects the weight of individual users, not just general statistics about weight and the legality of medical marijuana.
“I think this is a novel and important study, and a well-done study,” Saloner said. “But we still need to zero in on people who are actually consuming cannabis through a state program and more directly measure how their health changes.”