Researchers have found that marijuana users have lower fasting insulin levels compared to non-users, as well as healthier waist sizes and BMI scores.

Epidemiologists at the Harvard School of Public Health, the University of Nebraska College of Medicine, and Beth Israel Deaconess Medical Center have discovered something surprising about the metabolic effects of Cannabis sativa, better known as marijuana. A drug notorious for giving users the munchies can in fact help moderate blood sugar levels, waist size, and body mass index (BMI).

Their novel study, published in the current issue of The American Journal of Medicine, lays the groundwork for further investigation.

“Previous epidemiologic studies have found lower prevalence rates of obesity and diabetes in marijuana users,” said lead investigator Murray Mittleman, M.D., in a press release. “Ours is the first study to investigate the relationship between marijuana use and fasting insulin, glucose, and insulin resistance.”

Using data from the National Health and Nutrition Examination Survey (NHANES) collected between 2005 and 2010, the researchers found a significant link between the regular use of marijuana and better blood sugar control. In their analysis, participants who reported using marijuana in the past month had:

  • 16 percent lower fasting insulin levels
  • 17 percent lower levels of insulin resistance
  • higher levels of high-density lipoprotein cholesterol (HDL-C)
  • smaller waist circumference

The study incorporated data from 4,657 patients who completed a drug-use questionnaire, took a physical exam, and provided a blood sample following a nine-hour fast. Of these, 579 were current marijuana users, 1,975 had used it in the past, and 2,103 had never used marijuana.

Both insulin resistance and a large waist circumference have been linked to a greater risk of developing diabetes. The fasting insulin test used in this study is a common way to diagnose diabetes.

Marijuana users tend to consume more calories than non-users, but according to Mittleman, “two large studies found that marijuana users tended to be leaner than non-users, even after accounting for other behavioral and clinical characteristics.”

Mittleman told Healthline News that the mechanisms at work are still not entirely clear. “We know from previous work that drugs that block the cannabinoid receptors in the body have similar favorable metabolic effects,” he explained. “It is possible that some of the cannabinoid compounds in the marijuana used by the study participants may have had mixed effects, partially stimulating and partially blocking the [cannabinoid] receptors.”

Although marijuana has been illegal in the U.S. since 1937, its use continues unabated. By current estimates, 18.1 million Americans use marijuana, or about seven percent of the adult population.

The herb Cannabis sativa has been used for centuries to relieve pain, improve mood, and increase appetite. Medical marijuana is a synthetic form of its active ingredient, tetrahydrocannabinol (THC), now approved to treat the side effects of chemotherapy, AIDS-induced anorexia, nausea, and other medical conditions.

Currently, 19 states and the District of Columbia have legalized THC for medical use, and legislation is pending approval in 10 other states. The number of patients currently using medical marijuana is estimated at nearly 2.5 million, according to, based on data from state registries.

And state legalization of recreational marijuana is gaining momentum as well. So far, Colorado and Washington have legalized cannabis for all uses.

“With the increasing number of states that allow marijuana use for medical or recreational purposes, it is crucial to expand the research to better understand the biologic effects of marijuana,” said Mittleman.

The medical community is becoming increasingly vocal in the push to investigate the therapeutic properties and side effects of cannabis.

AJM editor-in-chief Joseph S. Alpert, M.D., made his position clear in an editorial accompanying the current study: “I would like to call on the NIH and the DEA to collaborate in developing policies to implement solid scientific investigations that would lead to information assisting physicians in the proper use and prescription of THC in its synthetic or herbal form.”