Antidepressants that cause weight loss

Antidepressants have a reputation for causing weight gain. This reputation has largely been proven true, with a few exceptions–bupropion (brand name Wellbutrin), fluoxetine (brand name Prozac), and Duloxetine (brand name Cymbalta). These medications have been found in multiple studies to be associated with weight loss, but not all of them result in long-term weight loss for patients. If you've been prescribed an antidepressant, you may be interested in the potential effects of the medication on your weight. Continue reading to learn more about maintaining a healthy weight on antidepressants that cause weight loss.

There are more than a dozen antidepressant drugs that are popularly prescribed. However, only three have been connected to weight loss in studies. 

1. Bupropion 

A study of the long-term weight loss effects of various antidepressants from 2016 found that non-smokers who took bupropion lost an average of 7.1 pounds over two years of treatment compared with those who used fluoxetine (brand name Prozac). However, these effects were neutralized among cigarette smokers: participants who used bupropion and smoked gained an average of 2.2 pounds compared with smokers who took fluoxetine over the course of the treatment period.

Bupropion also seems to help with weight loss maintenance. A 2012 study found that adults with obesity who took bupropion SR (standard release) in 300 mg or 400 mg doses lost 7.2% and 10% of their body weight, respectively, over 24 weeks and maintained much of that weight loss at 48 weeks. 

In fact, bupropion is part of the popular weight loss drug naltrexone-bupropion (brand name Contrave), which is FDA-approved for the treatment of overweight or obesity. 

2. Fluoxetine

In a 2022 review of studies involving adults with overweight or obesity, participants who took 60 milligrams (mg) of fluoxetine per day saw an average weight loss of 6 lbs over the first 6 months of treatment. However, participants who took a lower dose for a longer duration did not experience weight loss. That means that fluoxetine (Prozac) might not be the ideal option for someone who needs antidepressants as well as significant weight management, but the medication might be a good option for someone not looking to gain additional weight. 

3. Duloxetine

An analysis of 10 clinical studies conducted in 2006 found that participants who took duloxetine (brand name Cymbalta) to treat depression experienced minimal weight loss (1.5 lbs) after a short duration of treatment. However, after 52 weeks of treatment, participants gained an average of 2.4 lbs.

Antidepressants that may cause weight loss (whether long-term or temporary) including bupropion, fluoxetine, and duloxetine may do so for a variety of reasons:

• Some antidepressants can suppress your appetite, leading to a calorie deficit (you burn more calories than you consume.

• Depression and/or anxiety may impact eating habits, causing weight loss. As your mental health symptoms are treated, eating habits may return to normal, and you may regain weight. 

Gaining weight is much more common than losing weight when taking antidepressants. SSRIs (selective serotonin reuptake inhibitors) are second-generation antidepressants and typically have fewer side effects than older antidepressants. Still, the following SSRIs can cause weight gain:

• Citalopram (name brand Celexa)

• Paroxetine (name brand Paxil)

• Sertraline (name brand Zoloft)

• Fluoxetine (brand name Prozac) may cause weight loss in some, but can cause weight gain in others.

First-generation (older) antidepressants that can cause weight gain include:

• Nortriptyline (brand name Pamelor)

• Trazodone (brand name Desyrel)

• Amitriptyline

• Imipramine

• Monoamine oxidase inhibitors (MAOIs)

Weight gain on antidepressants may be caused by:

• Depression can cause inactivity, resulting in fewer calories burned.

• Increased appetite, resulting in more calories consumed.

• Antidepressants may impact metabolism, which means that the body burns calories more slowly.

Still, experts aren't exactly sure why weight changes occur with antidepressants. Antidepressant medications’ effect on weight is, in the words of one study, "only partially understood" and "poorly described.”

Some weight changes may be unavoidable when you’re taking an antidepressant, but there are steps you can take to address them. Fear of weight gain shouldn't keep you from taking antidepressants if you need them. Speak with your healthcare provider if you're bothered by weight changes—adjusting your diet, increasing exercise, or, in some cases, switching medications can be effective solutions.

Sometimes, antidepressants may affect weight because they’re doing what they’re supposed to do—improving anxiety and depression. Some people lose their appetite when they are anxious or depressed, while others tend to eat more. By addressing the symptoms of your underlying mental health condition, antidepressants may indirectly lead to changes in your weight.

Speaking with your healthcare provider will be the most important step you can take to address any weight change concerns. They can work with you to determine whether it would be useful to meet with a nutritionist, implement any lifestyle changes, or perhaps even change medications.

In some cases, depression can have a medical cause, such as hypothyroidism, vitamin B12 deficiency, low testosterone, or side effects of medication. A healthcare provider can diagnose and treat these.

Unfortunately, most cases of depression can’t just be addressed with a vitamin or supplement. Most cases of depression require comprehensive treatment by a healthcare professional, including antidepressant medications and psychotherapy.

Therapy

Research shows that antidepressants and cognitive behavioral therapy (CBT) are about equally effective for the treatment of depression. However, CBT may have more long-lasting effects and prevent relapse. The combination of the two treatments can be even better for some people. During CBT, therapists encourage patients to replace negative, unhelpful thoughts with more positive ones. 

Diet and exercise

Both aerobic and resistance exercises have been found to be effective at relieving depression. Some studies indicate that the Mediterranean diet is associated with a lower rate of depression. Still, what you eat isn’t going to cure depression. Instead, think of your diet and exercise as two components that might help improve your symptoms in combination with a comprehensive treatment plan. 

Other things that might improve depression include getting better sleep, increasing social interaction, and avoiding excessive alcohol and tobacco use. It goes without saying that if you’ve experienced depression, these can all be very difficult to achieve. Getting on the right treatment path with a combination of therapy and medication can often help jumpstart your ability to function in other walks of life as well.  

If you are feeling anxious or depressed, it’s important to seek out the help you need. Speak with your healthcare provider or a mental health professional to determine whether antidepressants, therapy, or a combination of treatments is right for you. If you are concerned about weight gain or weight loss on antidepressants, be sure to discuss that with your healthcare provider as well. Together, you can determine a treatment approach that’s best for you.

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Current version

January 18, 2024

Written by

Michael Martin

Fact checked by

Yael Cooperman, MD

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About the medical reviewer

Yael Cooperman, MD, Ro

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.