Why Does Wellbutrin® Cause Weight Loss? What We Know

What is Wellbutrin® (Bupropion)?

Wellbutrin® is a brand name for bupropion hydrochloride, an atypical antidepressant that doesn’t work the same as more commonly prescribed options, including SSRIs (selective serotonin reuptake inhibitors). 

Instead of targeting serotonin, bupropion acts as a norepinephrine-dopamine reuptake inhibitor (NDRI). This means that it increases the availability of dopamine and norepinephrine in the brain, which are involved in mood, motivation, attention, and energy.

The FDA has approved bupropion for the treatment of major depressive disorder (MDD), seasonal affective disorder (SAD), and smoking cessation (under the brand name Zyban®). It’s available in immediate-release (IR), sustained-release (SR), and extended-release (XL) formulations. 

However, you may have heard about it in relation to weight loss. So, what’s the connection? 

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Does Wellbutrin® Cause Weight Loss?

Unlike many antidepressants that are commonly associated with weight gain, Wellbutrin® is one of the few linked to weight reduction in some individuals. This has made it a frequent topic of interest among both patients and providers.

However, Wellbutrin® is not FDA-approved for weight loss on its own. When weight changes do happen, they’re considered a side effect of the medication, not its intended purpose. And ultimately, the amount of weight someone loses, if any, depends on factors such as dosage, individual metabolism, lifestyle habits, and whether bupropion is used alongside other treatments.

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How Bupropion May Influence Weight

The exact mechanism behind Wellbutrin® weight loss is still being studied. Researchers believe several factors may contribute to this effect.

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Appetite and Cravings

Bupropion’s effects on dopamine and norepinephrine may influence appetite and cravings in some individuals, though these effects are not fully understood and not consistent across all patients. These neurotransmitters are involved in the brain’s reward system, and by modulating their activity, bupropion may facilitate some individuals’ ability to resist impulsive or emotion-driven eating.

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Energy and Activity

Bupropion has mild stimulant-like effects, and some individuals report increased energy or motivation while taking it. This uptick in energy may lead to increased physical activity throughout the day, which may be associated with healthy weight management.

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Mood and Eating Behaviors

Depression can impact eating habits in various ways. While some people eat less, others may eat more when they feel low, turning to food for comfort. 

By improving mood and emotion regulation, Wellbutrin® may have cascading effects on other lifestyle factors. This may involve eating habits, and this behavioral shift, while indirect, can be a factor in weight management for some individuals.

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Research About Wellbutrin® Weight Loss

Several clinical studies have explored the connection between bupropion and body weight. These include:

• Premarketing Wellbutrin® SR trials: In placebo-controlled studies submitted to the FDA, weight loss of more than five pounds was reported in a subset of participants taking 300-400 mg/day, compared with 6% of those receiving a placebo.
• 48-week randomized controlled trial with lifestyle counseling: In a double-blind study of adults with obesity, participants taking bupropion SR 300 mg or 400 mg daily experienced greater average weight loss than placebo when combined with diet and exercise counseling. At 24 weeks, participants showed modest average reductions in body weight.
• A study in overweight and obese women: A placebo-controlled trial found that many women taking bupropion experienced some degree of weight loss during the initial treatment phase, with continued reductions observed among those who remained on therapy for 24 weeks.
• 2024 systematic review and meta-analysis: A meta-analysis of 25 studies involving over 22,000 participants found that bupropion use was associated with modest average reductions in body weight. In addition, greater reductions were observed when bupropion was combined with naltrexone.

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Bupropion and Naltrexone: Contrave® for Weight Management

In 2014, the FDA approved Contrave® (naltrexone HCl/bupropion HCl) for chronic weight management in adults who meet specific BMI criteria. It’s the only FDA-approved oral weight management medication combining these two ingredients.

The combination targets two brain regions linked to eating behavior, including the hypothalamus, which regulates appetite, and the mesolimbic dopamine circuit, which influences cravings and reward. Naltrexone, an opioid antagonist, is believed to enhance bupropion’s appetite-related effects by impacting areas of the brain involved in reward and pleasure.

Across four phase 3 clinical trials, participants taking the naltrexone-bupropion combination achieved greater average weight loss than placebo when used alongside lifestyle modifications.

It’s worth noting, however, that neither naltrexone nor bupropion is FDA-approved for weight loss when used individually. On top of this, Contrave® is intended for use alongside a reduced-calorie diet and increased physical activity.

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Side Effects and Safety Considerations

Like all medications, Wellbutrin® may cause side effects, such as:

• Dry mouth
• Headache
• Nausea
• Difficulty sleeping
• Dizziness
• Constipation

However, these side effects may be temporary and may lessen over time, though experiences vary.

At the same time, bupropion also carries important safety warnings. There is an increased risk of seizures, particularly at higher doses or in individuals with certain medical histories. The medication is further contraindicated in people with a history of seizures, eating disorders such as bulimia or anorexia, or those currently taking monoamine oxidase inhibitors (MAOIs). It also carries a boxed warning regarding the risk of suicidal thoughts and behavior, particularly in younger adults. Any concerns about side effects should be discussed with a licensed healthcare provider.

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Final Thoughts

So, does Wellbutrin® cause weight loss? For some people, it might. 

With that said, Wellbutrin® is not a weight loss drug. It’s a prescription antidepressant with specific FDA-approved uses, and any weight-related effects are secondary. If you’re considering bupropion for any reason, talk with a licensed healthcare provider. They can evaluate your health circumstance and determine whether it may be appropriate for you.