(CBS News by Michelle Castillo) You may have heard that marijuana smokers get hungry after using the drug, and the authors of a new study point out that marijuana users tend to take in more calories than their counterparts.
But, their study found that pot smokers aren't any more likely to be obese than non-smokers.
Equally surprising, the researchers found marijuana may actually be a tool in controlling blood sugar -- and may be key in helping diabetics keep their condition in check.
The new study, which was published on May 15 in The American Journal of Medicine, showed that regular marijuana use was linked to significantly lower levels of fasting insulin.
Smokers were also less likely to be insulin resistant, a condition where the body's cells no longer respond to a hormone that controls carbohydrates and fat metabolism called insulin. High levels of fasting insulin and insulin resistance could lead to diabetes.
Marijuana (Cannabis sativa) has been known to relieve pain, improve mood and increase appetite for patients who are prescribed it medicinally. The study's authors estimate that there are 17.4 million users in the U.S. alone, and 4.6 million of them use pot daily or almost daily.
The legitimacy of medical marijuana has been highly debated. Currently, nineteen states and the District of Columbia allow people to posses the Schedule 1 drug with a doctor's prescription. Washington and Colorado recently legalized pot for recreational purpose, but employees can still be fired if they test positive on a test according to their company's digression.
A synthetic form of the active ingredient, tetrahydrocannabinol (THC), has also been approved to treat side-effects of chemotherapy, AIDS-induced anorexia, nausea, and other medical conditions.
However, some opponents claim marijuana is a "gateway drug" that leads to more drug use, and that pot's negative effects outweigh any potential medical benefits. The National Institute on Drug Abuse says marijuana has the potential to cause problems in daily life including poorer mental and physical health, relationship problems, and less academic and career success compared to their peers who came from similar backgrounds but don't use the drug.
Researchers looked at 4,657 patients who were part of the National Health and Nutrition Survey (NHANES) between 2005 and 2010 and completed a drug use questionnaire. Out of the subjects, 579 were current marijuana users -- meaning they had used in the last 30 days -- 1,975 had used marijuana in the past but were not current users, and 2,103 had never inhaled or ingested marijuana.
They were then asked to fast for nine-hours before a blood sample was drawn to determine their fasting insulin and glucose levels. They also were tested using a homeostasis model assessment of insulin resistance (HOMA-IR) to figure out their insulin resistance.
Though pot smokers consumed more calories than their counterparts, participants who smoked marijuana had significantly smaller waistlines and lower body mass indexes (BMI), the researchers found. Large waist circumference has been linked to diabetes risk.
Those that used marijuana in the past month had lower levels of fasting insulin and HOMA-IR and higher levels of "good" high-density lipoprotein (HDL) cholesterol. Current users had a 16 percent lower fasting insulin level than people who said they never smoked pot, as well as 17 percent lower levels of insulin resistance. The association was weaker for people who said they used pot at least once, but not within the past month.
"We know from previous work that drugs that block the cannabinoid receptors in the body have similar favorable metabolic effects," lead investigator Dr. Murray Mittleman, a researcher with the department of epidemiology at the Harvard School of Public Health in Boston, told HealthLine. "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."
The findings remained the same even when people with diabetes were ruled out of the study.
"It is possible that the inverse association in fasting insulin levels and insulin resistance seen among current marijuana users could be in part due to changes in usage patterns among those with a diagnosis of diabetes (i.e., those with diabetes may have been told to cease smoking)," author Dr. Elizabeth Penner, a researcher with the department of epidemiology at the Harvard School of Public Health in Boston, said in a press release. "However, after we excluded those subjects with a diagnosis of diabetes mellitus, the associations between marijuana use and insulin levels, HOMA-IR, waist circumference, and HDL-C were similar and remained statistically significant."
The American Journal of Medicine editor-in-chief Dr. Joseph S. Alpert, professor of medicine at the University of Arizona College of Medicine in Tucson, Ariz. Commented in a press release that the findings were not only remarkable, but backed by solid evidence.
"We desperately need a great deal more basic and clinical research into the short- and long-term effects of marijuana in a variety of clinical settings such as cancer, diabetes, and frailty of the elderly," Alpert said." 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."