Does Smoking Weed Make You Gain Weight? 

Dr. Lee on the blog to present a new topic: body weight and marijuana. I’m super excited to dive into this subject because it comes up so often. The image of the lazy stoner crushing a bag of chips on the couch is all too common a trope in media and our collective cultural imagination. The evidence regarding marijuana’s effects on metabolism overall is a bit cloudy right now, but it seems like this particular topic is well validated…

The data shows that SMOKING WEED DOES NOT MAKE YOU GAIN WEIGHT! It actually looks like it makes you lose a few pounds. The big takeaway on this topic is that years of research have confirmed that the average marijuana user has a BMI slightly less than the average non-user. Here we will summarize some papers from the last 10 years.

I would like to stress this: that does NOT mean that you, dear marijuana user, are necessarily healthier than your non-using peers. Having a lower BMI does not always correlate with better health. Also, marijuana users have been historically shown also to have inferior diets and worse exercise habits in general. And, as we often discuss, the act of smoking itself is not healthy no matter how you shake it.

So are the Munchies Real?!

Short answer: yep! Long answer: There’s a fair amount of information (1,2) that shows that cannabis users, on average, have a higher caloric consumption than non-users. That makes it even more interesting that we maintain a slightly lower BMI.

Before writing this blog post, I would maybe have guessed that marijuana makes you add weight because of the munchies.

The ‘munchies’, or increased appetite, is common with marijuana use and sometimes one of the therapeutic aspects of its use. Marinol is a fairly commonly used medication that is derived from the THC molecule and often prescribed to patients to stimulate the appetite. When I did a lot of geriatric medicine (working with the elderly), I appreciated it for its relative lack of side effects. Even in traditional medical circles, we are kind of giving patients the munchies on purpose.

A pile of capsules next to an open bottle of Marinol labeled '5mg'.

And of course, I personally have done things to plates of food that would have been impossible without marijuana (It’s true…I’ve seen it -Dr. Do)

I love reading formal scientific papers and their descriptions of stoner phenomena! It’s a guaranteed good time. Look at the way they describe the munchies below, haha! (Alshaarawy et al. 2019)

Research with this sentence highlighted: "User anecdotes suggest that cannabis use promotes appetite."

What’s the Evidence?

There are numerous small and retroactive studies that show a correlative relationship between marijuana use and lower BMI. Beulaygue et al (2016) show a good example of a retrospective study that relies on surveys to prove a point. (3). Le Strat et al (2011) summarizes the results of two large-scale population surveys in American populations. Both of these studies confirm a 1.3-2.1 dip in BMI amongst marijuana users compared to their peers.

Having this historical information allows us to build on it and develop stronger research. Recently, a prospective study was published in 2019 by Alshaarawy et al (5) that did just that. Dr. Alshaarawy developed a prospective research protocol to follow patients over three years in order to see firsthand the changes in weight.

A prospective study enrolls patients and observes them for a period in the future. It’s considered far stronger than a retrospective study, which typically involves patients recalling the events of the past several years. Dr. Alshaarawy’s study was also published in a reputable journal and was conducted on a very nice cross-sectional American population. Snaps to all of that.

What did the Alshaarawy study find?

“Its evidence shows an attenuated BMI gain for cannabis-use subgroups when compared with never-users and a possible gradient as we look across subgroups of quitting, initiation, and persistent use.”

This basically means that cannabis users have a lower BMI and that patients that report higher amount of cannabis use might have an even lower BMI. Among all subgroups (separating patients by age, gender, and other factors), marijuana use was stillassociated with a decreased BMI and decreased weight gain over the study interval. Fascinating!

And wait…There’s More!

At this point, the statistics have made it pretty clear that marijuana use over time leads to a lower BMI. Still, we don’t really know why. But what other broad conclusions can we draw?

Another very interesting paper published by Vidot et al (2016) shows that marijuana users have a decreased risk of metabolic syndrome. Metabolic syndrome, in essence, is the state of being overweight, hypertensive, and out of shape.

“Metabolic syndrome was defined as ≥3 of the following: elevated fasting glucose, high triglycerides, low high-density lipoprotein cholesterol, elevated systolic/diastolic blood pressure, and increased waist circumference.”

The statistics shared in this study are pretty impressive. It defines emerging adults as the ages 18-24 and states that,

“Among emerging adults, current marijuana users were 54% less likely than never users to present with metabolic syndrome.”

Although this is a survey-based study and therefore not super-strong evidence, if true, it provides further evidence that marijuana may not be as bad as we’ve been taught for years.

Take-Aways

Marijuana is definitely associated with a significant decrease in BMI, but we don’t know why, and we don’t know how long it takes to get there.

In addition, it seems like the things in the plant are good for you in a number of different ways, our understanding of which expands yearly. The compounds in marijuana clearly have some type of positive effect on our metabolisms, but that doesn’t mean that marijuana is risk-free. Keep the smoke to a minimum, people!

Reviewing this information has been a breath of fresh air for me, and I’ll be happy to discuss it with other physicians and patients in the future.

— Dr. Lee

Citations

  1. Smit E, Crespo CJ. Dietary intake and nutritional status of US adult marijuana users: results from the Third National Health and Nutrition Examination Survey. Public Health Nutr. 2001 Jun;4(3):781-6. doi: 10.1079/phn2000114. PMID: 11415485.
  2. Le Strat Y, Le Foll B. Obesity and cannabis use: results from 2 representative national surveys. Am J Epidemiol. 2011 Oct 15;174(8):929-33. doi: 10.1093/aje/kwr200. Epub 2011 Aug 24. PMID: 21868374.
  3. Beulaygue IC, French MT. Got Munchies? Estimating the Relationship between Marijuana Use and Body Mass Index. J Ment Health Policy Econ. 2016 Sep;19(3):123-40. PMID: 27572145
  4. Le Strat Y, Le Foll B. Obesity and cannabis use: results from 2 representative national surveys. Am J Epidemiol. 2011 Oct 15;174(8):929-33. doi: 10.1093/aje/kwr200. Epub 2011 Aug 24. PMID: 21868374.
  5. Alshaarawy O, Anthony JC. Are cannabis users less likely to gain weight? Results from a national 3-year prospective study. Int J Epidemiol. 2019 Oct 1;48(5):1695-1700. doi: 10.1093/ije/dyz044. PMID: 30879064; PMCID: PMC6857742.
  6. Vidot DC, Prado G, Hlaing WM, Florez HJ, Arheart KL, Messiah SE. Metabolic Syndrome Among Marijuana Users in the United States: An Analysis of National Health and Nutrition Examination Survey Data. Am J Med. 2016 Feb;129(2):173-9. doi: 10.1016/j.amjmed.2015.10.019. Epub 2015 Nov 5. PMID: 26548604; PMCID: PMC4718895.