A Preliminary Study on the Influence of Cannabis and Opioid Use on Weight Loss and Mental Health Biomarkers Post-Weight Loss Surgery

• This study used objective biological measurements to examine how cannabis and opioid use influence both weight loss and mental health after weight loss surgery.
• After bariatric surgery, the body processes substances differently due to smaller stomach size, changed absorption, and altered appetite hormones.
• The study measured stress hormone (cortisol) and mood-regulating chemical (serotonin) markers, providing more objective assessment than self-reported use alone.
• Some patients experience 'addiction transfer,' where compulsive eating is replaced by other compulsive behaviors after surgery.
• This is one of seven publications by the research team examining substance use and behavioral health after bariatric surgery.
• For patients with substance use concerns, this demonstrates evidence-based, nonjudgmental guidance is part of comprehensive care.

Why This Study Was Needed

Some bariatric patients use cannabis, opioids or both, and these substances affect mood, appetite and stress hormones. How they relate to anxiety, depression and weight loss after surgery was unclear.

How the Study Was Done

This preliminary, cross-sectional study included 18 patients whose duodenal tissue (the first part of the small intestine) was sampled during surgery to measure serotonin, a mood-regulating chemical, and cortisol, the main stress hormone. Patients reported their cannabis and opioid use and completed standard depression and anxiety inventories, and total weight loss was calculated.

What the Study Found

• 27.8% used cannabis only, and 16.7% used both cannabis and opioids; no one used opioids alone.
• Patients using both substances had more depressive symptoms and greater weight loss (34.1%) than cannabis-only users (23.2%).
• Cannabis-only users had higher serotonin and cortisol levels than combination users and never users.

What This Means for Patients

Substance use after surgery is tied to mood and stress in ways we are only beginning to understand. Greater weight loss in combination users is not a benefit if it comes with worsening depression. If you use cannabis or opioids, tell your team so they can support both your mental and physical health. See Mental Health, Body Image, and Alcohol After Bariatric Surgery.

Clinical Pearls

• Combined cannabis and opioid use was associated with more depressive symptoms.
• Gut tissue biomarkers of serotonin and cortisol differed by substance use pattern.
• Opioid use after bariatric surgery warrants careful screening.

Strengths and Limitations

This study is unusual in pairing tissue biomarkers with self-reported substance use. With only 18 patients and a cross-sectional design, it is hypothesis-generating; larger studies are needed to confirm the patterns.

Expert Commentary

Rapid weight loss is not always a sign that a patient is doing well. In this small study, patients using both cannabis and opioids lost more weight but were also more depressed. That is a reminder to look at the whole person at every follow-up visit.

— Dr. Nestor de la Cruz-Muñoz

Related Research

• Postoperative Marijuana Use and Disordered Eating Among Bariatric Surgery Patients
• Self-Reported Depression and Duodenal Cortisol Biomarkers Are Related to Weight Loss in Young Metabolic and Bariatric Surgery Patients