Do Antidepressants Cause Weight Gain?

Some antidepressants are linked to weight gain, but the average amount is small and it differs by medication. The largest head-to-head comparison so far, published in Annals of Internal Medicine in 2024, followed 183,118 patients across 8 U.S. health systems. Six months after starting, people taking escitalopram had gained about 0.41 kg (0.9 pounds) more than people taking sertraline, while people taking bupropion had gained about 0.22 kg (0.5 pounds) less.

The same study reported more than average. Escitalopram, paroxetine and duloxetine were each associated with a 10% to 15% higher risk of gaining at least 5% of starting body weight, so a small average hides a group of people who gain a meaningful amount. And only 28% to 41% of patients were still taking their medication at six months, which means the real effect for people who stay on treatment may be larger than the headline figures. This post covers which antidepressants are linked to the most and least weight change, why it happens, and what to do about it.

This article is for general education and is not medical advice. Talk with your prescriber before starting, stopping or changing any medication.

Do All Antidepressants Cause Weight Gain?

No. Weight change varies from one antidepressant to another, and from one person to another on the same drug.

The 2024 study, led by Petimar, compared eight common first-line antidepressants using electronic health records from 2010 to 2019. It used sertraline as the reference point. Five medications were linked to more weight gain than sertraline, one was about the same, and one was linked to less.

The authors summarized it this way: small differences in average weight change were found between the eight medications, with bupropion consistently showing the least weight gain.

Which Antidepressants Are Linked to the Most and Least Weight Gain?

These are the estimated differences in weight change at six months, each compared with sertraline, from the Annals of Internal Medicine study.

• Escitalopram (Lexapro): 0.41 kg more, about 0.9 pounds.

• Paroxetine (Paxil): 0.37 kg more, about 0.8 pounds.

• Duloxetine (Cymbalta): 0.34 kg more, about 0.75 pounds.

• Venlafaxine (Effexor): 0.17 kg more, about 0.4 pounds.

• Citalopram (Celexa): 0.12 kg more, about 0.3 pounds.

• Fluoxetine (Prozac): about the same as sertraline.

• Bupropion (Wellbutrin): 0.22 kg less, about 0.5 pounds.

These numbers are differences between drugs. They are not the total amount a person gains, and they are averages across a very large group.

The study was observational. Patients were not randomly assigned to a medication, so the researchers used statistical methods to account for differences between groups. They also listed limits, including incomplete data on whether patients kept taking their medication and incomplete weight measurements over time.

How Much Weight Gain Should You Expect?

On average, the difference between one antidepressant and another was under a pound at six months. That is small enough that it should not be the only factor in choosing a medication.

The more useful figure is the chance of a larger gain. Escitalopram, paroxetine and duloxetine were associated with a 10% to 15% higher risk of gaining at least 5% of baseline weight compared with sertraline. Bupropion was associated with a 15% lower risk. For a person who weighs 180 pounds, 5% is 9 pounds.

No study can tell you in advance which group you will fall into. What it can do is help you and your prescriber weigh the options if weight is a concern for health or personal reasons. The post on the most common medications for depression gives background on the drugs compared here.

What About Mirtazapine and Other Antidepressants Not in the Study?

The 2024 study did not include every antidepressant. Mirtazapine (Remeron) is one that was left out, and its own FDA label addresses weight directly.

According to the Remeron label, appetite increase was reported in 17% of patients taking mirtazapine in U.S. controlled studies, compared with 2% on placebo. Weight gain of 7% or more of body weight was reported in 7.5% of patients on mirtazapine, compared with 0% on placebo. The label lists increased appetite and weight gain among its warnings.

That effect is not always unwanted. For someone whose depression has caused poor appetite and weight loss, a prescriber may see it as useful. It is a good example of why the right medication depends on the person.

Why Can Antidepressants Change Your Weight?

More than one thing can be going on, and not every pound is a drug effect.

Depression itself changes appetite and weight. The National Institute of Mental Health lists "changes in appetite or unplanned weight changes" among the common symptoms of depression. When treatment works and appetite returns, some weight change reflects recovery.

Some medications also increase appetite directly, as the mirtazapine label shows.

Then there is everything else that affects weight over six months or two years: age, activity, sleep, other medications and other health conditions. Sorting out the cause is part of what a follow-up visit is for. The post on managing psychiatric medication side effects covers how those conversations work.

What Should You Do If You Are Gaining Weight on an Antidepressant?

Start by telling your prescriber. Do not stop the medication on your own. The National Institute of Mental Health advises talking to a health care provider before starting or stopping any medication, and stopping abruptly can cause its own symptoms, described in the post on the side effects of stopping antidepressants.

Bring specifics to the visit: your weight before starting, your weight now, when the change began, and any changes in appetite, sleep or activity. With that information, your prescriber can consider the options, which may include watching and waiting, adjusting the dose, addressing sleep or other contributors, or switching to a different medication.

Keep the trade-off in view. A medication that has lifted a serious depression is doing something valuable, and untreated depression carries real risks of its own. The goal is a plan that protects both your mood and your physical health. The post on whether you can stop psychiatric medication on your own explains why changes should be supervised.

Should Weight Decide Which Antidepressant You Take?

It can be one factor. The authors of the 2024 study wrote that clinicians could consider potential weight gain when starting antidepressant treatment.

It should not be the only factor. Your symptoms, medical history, other medications, past response to treatment and side effects you most want to avoid all matter. Bupropion showed the least weight gain in the study, but it is not the right choice for everyone, and only a prescriber who knows your history can judge that.

Say so at the start if weight is a concern for you. It is a legitimate medical consideration, and raising it early is easier than changing course later.

FAQ

Which antidepressant causes the least weight gain?

In a 2024 study of 183,118 patients, bupropion was consistently associated with the least weight gain among eight common antidepressants.

Does Lexapro cause more weight gain than Zoloft?

On average, slightly. At six months, people taking escitalopram (Lexapro) had gained about 0.41 kg, or 0.9 pounds, more than people taking sertraline (Zoloft).

Does Prozac cause weight gain?

In the same study, weight change with fluoxetine (Prozac) at six months was similar to sertraline.

Will I lose the weight if I stop my antidepressant?

That is not something the 2024 study measured. Stopping without guidance can bring back depression or cause discontinuation symptoms, so talk with your prescriber before making a change.

How soon does weight gain start?

The study followed patients for 24 months, with the main comparison at six months. If you notice a change earlier, report it to your prescriber.

Is weight gain a reason to switch antidepressants?

It can be, especially if the gain is significant or affects your health. Switching is a decision to make with your prescriber, who can weigh it against how well the current medication is working.

Medication Management for Depression in Greensburg, PA

T and C Psychiatric Services LLC in Greensburg, PA provides medication management with regular follow-ups to check effectiveness and adjust treatment as needed. Its board-certified nurse practitioners treat depression, anxiety and other conditions through in-person visits and online and remote services.

If you or someone you know is in crisis, call or text 988 to reach the 988 Suicide & Crisis Lifeline, text HOME to 741741 to reach the Crisis Text Line, or call 911 for an immediate emergency.

Visit T and C Psychiatric Services or call 724-951-2413 today. Contact us for more information.