Despite cannabis being associated with increased appetite, bariatric surgery patients who used cannabis weekly had equivalent weight loss outcomes at every time point through two years.
Read this if you use cannabis and are considering or have had bariatric surgery — the data suggests it won't hurt your weight loss results.
What the researchers found
One of the most common concerns about cannabis use after bariatric surgery is the 'munchies' — cannabis stimulates appetite, and the whole point of bariatric surgery is to restrict eating. This study put that concern to the test and found it largely unfounded.
Among 364 sleeve gastrectomy patients, 31 (8.5%) were weekly cannabis users. The researchers tracked weight loss at 1 week, 1 month, 3 months, 6 months, 9 months, 1 year, and 2 years post-surgery. At every single time point, there was no significant difference in excess weight loss between cannabis users and non-users.
Interestingly, the cannabis group actually trended toward slightly more weight loss, though the difference wasn't statistically significant. Secondary outcomes — post-operative nausea and vomiting, length of hospital stay, readmission rates, and need for additional intervention — were also similar between groups.
This is reassuring data for the growing number of bariatric patients who use cannabis, whether medicinally or recreationally. The concern that appetite stimulation from cannabis would undermine surgical weight loss appears not to materialize in practice, at least through two years of follow-up.
Why it matters
About 8% of bariatric surgery patients use cannabis, and that number is growing as legalization expands. Surgeons and patients need to know whether cannabis use will compromise outcomes. This study provides the first focused evidence that it doesn't — giving clinicians data to counsel patients rather than relying on theoretical concerns about appetite stimulation.
The numbers in context
364 sleeve gastrectomy patients: 31 cannabis users (8.5%), 333 non-users. No significant difference in excess weight loss at any time point from 1 week through 2 years. Post-operative nausea/vomiting, length of stay, readmission, and reintervention rates were comparable between groups.
How the study worked
Retrospective cohort study of 364 sleeve gastrectomy patients divided into cannabis users (at least once weekly, n=31) and non-users (n=333). Primary outcome was excess weight loss (EWL) at multiple time points through 2 years. Secondary outcomes included post-operative nausea/vomiting, length of stay, readmission, and need for additional intervention. Cannabis users were also surveyed by phone for additional information.
Who was studied
N=364 adults undergoing sleeve gastrectomy, 8.5% cannabis users, US-based study.
What this study cannot tell us
Retrospective design with a small cannabis user group (31 patients). Cannabis use was self-reported and defined broadly as 'at least once weekly' — dosage, potency, and route of administration varied. No data on whether cannabis use patterns changed after surgery. Single-center study (sleeve gastrectomy only, not gastric bypass). The cannabis group may differ from non-users in unmeasured ways. Two-year follow-up, while meaningful, may not capture very long-term differences.
How to read the evidence
This is a retrospective cohort study with a reasonable sample but a small cannabis user subgroup (31 patients). The consistent null finding across multiple time points is reassuring but should be confirmed in larger, prospective studies.
When this study was published
Published in 2023. As cannabis legalization expands, more bariatric programs may begin collecting cannabis use data prospectively.
The bigger picture
This study challenges a simplistic understanding of cannabis and appetite. While THC does stimulate appetite acutely, the long-term metabolic picture is more complex. Epidemiological studies have consistently shown that cannabis users tend to have lower BMI than non-users — a paradox this surgical data reinforces. The findings connect to broader questions about cannabis and metabolism that cut across the research database.
Replication
Not stated in abstract.
Funding
Not reported in abstract.
Conflicts of interest
Not reported in abstract.
Questions still open
- Does the route of cannabis consumption (edibles vs. smoked) affect post-surgical eating patterns differently? Would higher-frequency or higher-dose cannabis use produce different results? Does cannabis use affect micronutrient absorption or nutritional outcomes after bariatric surgery, even if weight loss is comparable?
Read the original research
Weight loss outcomes are not compromised in bariatric patients using cannabis.
Surgical endoscopy, 37(3), 2194-2201
Surgical Endoscopy is a peer-reviewed journal focused on minimally invasive surgery.
Citation
Huang, Estella Y; Broderick, Ryan C; Li, Jonathan Z; Serra, Joaquin L; Ahuja, Pranav; Wu, Samantha; Genz, Michael; Grunvald, Eduardo; Kunkel, David C; Sandler, Bryan J; Horgan, Santiago; Jacobsen, Garth R. (2023). Weight loss outcomes are not compromised in bariatric patients using cannabis.. Surgical endoscopy, 37(3), 2194-2201. https://doi.org/10.1007/s00464-022-09453-x
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