New Report Claims Weed Helps You Lose Weight! Not So Fast…

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New year, new you! Old you was lazy and dumb. New you is productive and smart! And of course, old you was fat while new you is sexxxy. According to surveys, the top resolutions this year are the same as every year: eat healthier, exercise more, lose weight. And for most Americans, those are really good goals, because we are very fat and unhealthy. Yes, myself included — I’ve gained about 15 pounds since Trump was elected two years ago, and while I don’t have problems with my cholesterol and I’m nowhere near to being at risk for Type II diabetes or other problems linked with obesity, I do have a degenerative spinal disc that I’ve dealt since I was a teen, and when my weight creeps up, it literally cripples me. So yeah, I have to join the boring masses with the same boring resolution: be less fat.

I say that it happened since the election because I’ve noticed that I’ve been eating more and drinking more alcohol since then, and alcohol has shitloads of calories. It’s easy to drink and drink without filling up, and once you’re drunk it’s easy to raid the fridge for any fatty, salty, delicious thing you can find. If you drink enough whiskey and then eat enough mozzarella sticks, you may be able to forget about Donald Trump for up to four hours. It’s remarkably effective, but yeah, not great for your body.

That’s why cutting out alcohol is a good first step if you want to lose weight and be healthier, and for several of my friends out here in California, they’ve found it pretty easy to drop alcohol — and replace it with weed. Cannabis is easy and legal to get here, and if you drink alcohol to be more social or to relax at the end of the day, weed can be a good replacement for some people. And here’s the kicker: weed can help you lose weight.

Biologists at South Bend University have just published a meta-analysis in Cannabis and Cannabinoid Research, the premiere journal for scientists who are also giant potheads, showing clear evidence that people who use cannabis have lower BMIs than non-users. Digging further into the data allowed the researchers to offer some hypotheses about the causation and the reason for it.

One hypothesis is the one that I stated: potheads, particularly younger people, may be drinking less alcohol, and also just straight up being too lazy to make mozzarella sticks. On the other end, older people who start using cannabis may actually become more active, since it can help with pain relief and other medical issues.

But there is one confounding factor: the researchers report that in several studies, frequent cannabis users had lower BMI but higher caloric intake compared to non-users. And not a small amount — we’re talking 500 to 600 calories, like an extra giant donut a day, and in one study up to 1,000 calories more. That’s tough to work out in the gym — as they say, you can’t outrun your fork, so the researchers looked at other possible explanations.

Their main hypothesis is that cannabis stimulates a receptor in your brain that can, basically, amp up your metabolism and make you less likely to absorb the calories from the typical processed food Western diet. Their paper includes some observations that suggests this might be true, but it’s worth noting that there is no direct, clinical evidence.

But more concerning is the initial assumption that all of this conjecture is based upon: the idea that if you use cannabis, you consume more calories but have a lower BMI. The researchers base this statement on four studies they examined. Let’s go through them one by one:

In “Cannabis use in relation to obesity and insulin resistance in the inuit population”, the researchers note that the subjects who used marijuana had higher caloric intake, but it wasn’t statistically significant. Honestly if that’s the case it should not have even been mentioned. Statistical significance is there for a reason — it helps us tell what is likely to be a real effect and what is more likely to just be statistical noise, or random chance. Not statistically significant? Throw it in the trash.

In “Marijuana use, diet, body mass index, and cardiovascular risk factors,” they found cannabis users to have increased caloric intake of 600 calories but about the same BMI as non-users, but the calories were self-reported. No one in a lab was determining how many calories each of 3,600 people were consuming every day. So really all we can say is that cannabis users think they eat more than non-users think they eat, but also they’re fucking high, so if they’re anything like me when I’m high, they’re not really the most trustworthy sources of information. The same is true of the next study: in “Dietary intake and nutritional status of US adult marijuana users: results from the Third National Health and Nutrition Examination Survey,” they used a survey, aka self-reported data, to determine caloric intake. They found that potheads said they ate 500 calories more than non-potheads but had slightly lower BMI. Did they? Maybe! But to be sure we’d need to put people in a clinical setting where their food intake is strictly monitored along with their weight, and then we can know for sure.

Luckily, that’s exactly what happened in the fourth study cited by these researchers! In “Effects of smoked marijuana on food intake and body weight of humans living in a residential laboratory,” they put six men in a laboratory for about two weeks and monitored everything they ate while giving them two joints per day to smoke. Yes, six men isn’t a great sample size but it IS a good start and I do find it a bit more convincing than asking people to self-report their calories.

Sure enough, in this lab setting the men did consume more calories — not during mealtimes, but during snacktimes, taking in a whopping extra 1,000 calories per day. And how much weight did these guys lose? Well, let me just quote the authors: “Increases in body weight during periods of active marijuana smoking were greater than predicted by caloric intake alone.” Increases in weight were greater than predicted by calories alone. They gained weight, and they gained more weight than the researchers thought possible by how many calories they were taking in. That’s…that’s not what the meta-analysis seemed to take away from that study.

So sadly I’m not sure that there’s really anything there with regards to cannabis helping you lose weight, though I will state with a high (haha) degree of confidence that if you are a heavy drinker and you switch alcohol for weed, and if you try to limit your snacking while high, you’re gonna lose weight. But it may not be the magical weightloss cure the meta-analysis authors were hoping for.

Rebecca Watson

Rebecca is a writer, speaker, YouTube personality, and unrepentant science nerd. In addition to founding and continuing to run Skepchick, she hosts Quiz-o-Tron, a monthly science-themed quiz show and podcast that pits comedians against nerds. There is an asteroid named in her honor. Twitter @rebeccawatson Mastodon Instagram @actuallyrebeccawatson TikTok @actuallyrebeccawatson YouTube @rebeccawatson BlueSky

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  1. So many studies of weight loss fail because of self reporting in which people are bound to fool themselves. In fact if calorie intake AND usage is not strictly monitored in a weight loss study, it can have no scientific value at all.

    This is why I weep at so many of the Michael Mosely documentaries, which would otherwise be interesting – the opportunity was right there, they had a good idea, they had the volunteers, but usually they manage to flub it in some way.

    IDK, fuckin doctors, they look like scientists, they talk like scientists, but as Einstein said, there isn’t a single scientist among them.

    Speaking of which, in the last study, where was the control group??

  2. If a study measures ‘x’ and finds it statistically insignificant, reporting that fact obviates the need to answer “Yabbut, did you consider/measure ‘x’?” over and over again.

    1. Yes. It may just mean that larger numbers are needed.
      A statistically insignificant effect may still be important.

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