Naltrexone for weight loss: Does it work?

An Older Drug Gets a Second Look in the GLP-1 Era

Dr. Westin Childs, whose metabolic health content has built a substantial following, examines naltrexone's role in weight management in this video with over 106,000 views. Naltrexone is not a GLP-1 medication. It is an opioid receptor antagonist that has been used for decades to treat alcohol and opioid dependence. But its involvement in the weight loss space, primarily through the combination drug Contrave (naltrexone/bupropion), makes it directly relevant to anyone comparing their pharmacological options for weight management.

The conversation about naltrexone in weight loss has become more nuanced as GLP-1 medications have raised the bar for what pharmaceutical weight loss looks like. Before Wegovy and Zepbound, losing 5-7% of body weight with medication was considered a good result. Now that 15-22% weight loss is achievable with GLP-1 drugs, older medications like naltrexone face a tougher comparison. But that comparison is not entirely fair, and understanding where naltrexone fits in the broader toolkit matters.

How Naltrexone Affects Weight

Naltrexone blocks opioid receptors in the brain, which has an indirect but meaningful effect on food reward and appetite. The endogenous opioid system (your body's natural opiate molecules, endorphins and enkephalins) plays a role in the pleasure you experience from eating, particularly from highly palatable foods rich in sugar, fat, and salt. When naltrexone blocks these opioid receptors, it reduces the hedonic (pleasure-based) drive to eat. Food becomes less rewarding, and the compulsive urge to eat beyond hunger diminishes.

This mechanism is fundamentally different from how GLP-1 medications work. GLP-1 drugs suppress appetite through gut-brain signaling, gastric emptying delay, and hypothalamic satiety center activation. Naltrexone works primarily on the reward circuitry. In theory, these two approaches are complementary, targeting different aspects of the complex neural control of eating behavior.

Dr. Childs explains that naltrexone alone at standard doses (50 mg, used for addiction treatment) produces modest weight loss, typically 2-4% of body weight. This is statistically better than placebo but clinically unimpressive compared to GLP-1 outcomes. The weight loss effect is more pronounced in patients who are emotional eaters or binge eaters, whose eating behavior is more strongly driven by the reward pathways that naltrexone modulates.

Contrave: The Combination That Made It to Market

The more clinically relevant weight loss application of naltrexone is in the combination drug Contrave, which pairs low-dose naltrexone (8 mg) with bupropion (90 mg) in an extended-release tablet taken twice daily. Bupropion is an antidepressant (Wellbutrin) that also affects appetite through its action on dopamine and norepinephrine pathways. Together, naltrexone and bupropion target multiple neurotransmitter systems involved in appetite regulation and food reward.

The COR clinical trial program for Contrave showed average weight loss of approximately 5-8% of body weight over 56 weeks, which was significantly better than placebo and better than either drug alone. This places Contrave in a middle tier of weight loss medications: more effective than lifestyle intervention alone but substantially less effective than GLP-1 receptor agonists or tirzepatide.

Contrave's side effect profile includes nausea (which can be significant in the first few weeks but typically improves), constipation, headache, insomnia, and dry mouth. Because bupropion lowers the seizure threshold, Contrave is contraindicated in patients with seizure disorders, eating disorders (particularly bulimia, which increases seizure risk), or those undergoing abrupt discontinuation of alcohol or benzodiazepines.

Low-Dose Naltrexone: The Off-Label Conversation

Dr. Childs also discusses low-dose naltrexone (LDN), typically dosed at 1.5-4.5 mg, which has gained significant popularity in integrative and functional medicine circles. At these very low doses, naltrexone is believed to have different effects than at the standard 50 mg addiction dose. The proposed mechanism involves brief opioid receptor blockade that triggers a compensatory upregulation of endogenous opioid production (an "opioid rebound" effect) and modulation of inflammatory pathways through effects on Toll-like receptor 4.

The evidence for LDN's direct weight loss effects is limited. Most LDN research focuses on autoimmune conditions, chronic pain, and fibromyalgia rather than obesity. However, some practitioners report weight loss as a secondary benefit in patients taking LDN for other conditions, possibly through reduced inflammation, improved sleep, or modulation of the reward system at sub-therapeutic opioid blockade doses.

Dr. Childs is appropriately cautious about LDN claims. He notes that the evidence base is much weaker than for standard-dose naltrexone or Contrave, and that most LDN research consists of small studies, case reports, and clinical observation rather than large randomized trials. Patients interested in LDN should work with a prescribing physician familiar with its use and should not expect weight loss results comparable to GLP-1 medications.

Where Naltrexone Fits in a GLP-1 World

Dr. Childs positions naltrexone-containing medications as options for specific patient populations rather than as first-line weight loss treatments. Patients who cannot access GLP-1 medications due to cost, insurance coverage, or supply issues may find Contrave more accessible (it is available as a generic, making it significantly cheaper than brand-name GLP-1 drugs). Patients who refuse injectable medications and cannot tolerate oral semaglutide may prefer an oral alternative like Contrave.

Patients whose eating behavior is primarily reward-driven (emotional eating, binge eating, food addiction patterns) may benefit from naltrexone's specific targeting of the opioid reward system. While GLP-1 medications also modulate reward pathways, naltrexone's mechanism is more directly targeted at the hedonic pleasure component of eating. For some patients, combining a GLP-1 medication with low-dose naltrexone or Contrave may provide complementary benefits that neither drug achieves alone.

This combination approach (GLP-1 plus naltrexone-based therapy) is not yet well-studied in clinical trials, but some obesity medicine specialists are prescribing it off-label for patients who need additional reward-pathway modulation on top of their GLP-1 therapy. The rationale is sound (different mechanisms targeting different aspects of appetite and eating behavior), but the safety and efficacy data for the combination is limited to clinical observation rather than rigorous trials.

Practical Considerations for Patients

If you are considering naltrexone or Contrave for weight management, here are the practical factors Dr. Childs recommends evaluating. Cost: generic naltrexone is inexpensive ($20-50/month), and generic Contrave (naltrexone/bupropion) is available at moderate cost ($80-150/month), both substantially cheaper than brand-name GLP-1 medications. Side effects: nausea is common initially but usually resolves. Insomnia and headache are reported by some patients. The bupropion component can cause anxiety or agitation in susceptible individuals.

Drug interactions are important to review with your physician. Because naltrexone blocks opioid receptors, it renders opioid pain medications ineffective. If you take naltrexone and later need emergency surgery or pain management, your medical team needs to know you are on an opioid blocker. Wearing a medical alert bracelet or carrying a medication card is recommended for naltrexone users.

Effectiveness expectations should be calibrated appropriately. Contrave produces 5-8% weight loss on average. If your goal requires 15%+ weight loss, Contrave alone is unlikely to get you there. It may serve as a bridge while you work toward GLP-1 access, or as an adjunct to GLP-1 therapy for additional reward-pathway modulation, but it is not a substitute for the higher-efficacy options currently available.

The Bigger Picture of Multi-Target Pharmacotherapy

Naltrexone's story illustrates a broader principle in obesity medicine: effective weight management often requires targeting multiple biological systems simultaneously. Appetite is regulated by GLP-1 and other gut hormones, insulin, leptin, ghrelin, endocannabinoids, opioid peptides, serotonin, dopamine, and norepinephrine, among others. No single drug can address all of these pathways. The future of obesity pharmacotherapy almost certainly involves rational combinations of medications that target complementary pathways, similar to how hypertension and HIV are treated with multi-drug regimens.

Dr. Childs's video is a useful contribution to this evolving conversation, helping patients understand where naltrexone fits within the growing toolkit of weight management medications and how to evaluate their options based on their specific clinical situation, budget, and treatment goals.

Real-World Patient Experience and Expectations

Understanding what day-to-day life on naltrexone or Contrave looks like helps set realistic expectations. Patients typically start at a low dose and titrate up over 2-3 weeks to the full therapeutic dose. The most common experience during the first week is mild to moderate nausea, which usually resolves within 7-14 days. Some patients report vivid dreams or mild insomnia during the adjustment period, particularly from the bupropion component.

Once at the full dose, the appetite suppression from Contrave is generally described as more subtle than what GLP-1 patients report. Rather than dramatically reduced hunger, Contrave patients often notice that they are less driven to eat for emotional reasons, less likely to seek out snacks between meals, and better able to stop eating when they are physiologically satisfied. The experience is less about not being hungry and more about not being compelled to eat when you are not hungry. This distinction matters because patients expecting the dramatic appetite shutdown that GLP-1 users describe may feel disappointed by the more nuanced effect.

The weight loss trajectory on Contrave is also different from GLP-1 therapy. GLP-1 patients often see noticeable weight loss within the first 2-4 weeks. Contrave users may not see significant scale movement for 4-8 weeks, and the rate of loss is typically slower throughout treatment. Physicians generally assess Contrave response at the 12-week mark: if a patient has not lost at least 5% of body weight by week 12 at full dose, the medication is unlikely to produce meaningful long-term results and alternative options should be discussed.

For patients who do respond to Contrave, the long-term question is the same as with any weight management medication: what happens when you stop? Weight regain after discontinuing Contrave is common, similar to the pattern seen with GLP-1 medications. This shows the reality that obesity is a chronic condition requiring ongoing management, whether through medication, behavioral strategies, or both.