Why SSRIs Cause Weight Gain

Weight gain can be a distressing side effect of certain antidepressants in the class of selective serotonin reuptake inhibitors (SSRIs), some of which include Zoloft, Paxil, and Lexapro. Typically, SSRI weight gain is modest. However, the upset it causes can complicate recovery from the condition being treated.

Common SSRIs and Their Effect on Weight

The most commonly prescribed SSRIs in the United States include Zoloft (sertraline), Celexa (citalopram), Prozac (fluoxetine), and Lexapro (escitalopram). These medications work by inhibiting serotonin reuptake, thereby increasing its levels in the brain.

How common is weight gain with these drugs? In one study involving 294.719 people, 11.2% of individuals prescribed antidepressants had a body weight increase of 5% or higher in the first year. Additionally, their weight gain risk continued to stay elevated for more than six years.

Most antidepressants are associated with weight gain, but the risk of weight gain is higher with some SSRIs than with others. For example, some research suggests that Paxil (paroxetine) is linked to greater weight gain than Zoloft or Prozac.

SSRI Weight Gain or Loss Tied to Length of Use

Research looking at the effects of individual SSRIs on weight gain is complex. One reason is that the short-term effects of antidepressants on weight can differ from their long-term effects.

For example, research has found that some SSRIs are associated with weight loss in the short term. In this study, "short term" was described as four months or less. After this time, the weight loss effect tended to disappear.

Why SSRIs Cause Weight Gain

Experts aren't certain about the mechanisms by which SSRIs lead to weight gain, but there are some theories. It may be that the drugs trigger changes in metabolism that cause the body to use calories less efficiently, or that they affect the appetite, leading to overeating.

Another hypothesis is that weight gained while taking an SSRI may be partially due to the fact that some people don't feel like eating when they're depressed, causing them to lose weight. Once they start taking an antidepressant, however, they begin to feel better and as a result, their appetite may come back, they may eat more, and eventually return to their previous weight.

Other Types of Antidepressants Linked to Weight Gain

Several types of antidepressants can cause weight gain, though to different extents. One study compared many of these to the SSRI citalopram. It found that duloxetine, a serotonin and norepinephrine reuptake inhibitor (SNRI), resulted in similar weight gain amounts.

Conversely, three other antidepressants were associated with "significantly less weight gain" than citalopram. In order of greatest to least difference, they were:

• Nortriptyline hydrochloride - a tricyclic antidepressant
• Amitriptyline - another tricyclic sold under the brand name Elavil
• Bupropion - an atypical antidepressant sold under the brand name Wellbutrin
  

How to Prevent Weight Gain When Taking SSRIs

If you're concerned about weight gain while taking antidepressants, you may be tempted to stop taking your medication. But before you do, talk to your healthcare provider. In all likelihood, you can avoid gaining weight without sacrificing your mental health.

Here are a few things you can do to manage your weight (which includes stopping weight gain as well as losing weight), improve your health, and help you have a healthy relationship with food and eating while taking an SSRI.

Mindful Eating

Eating mindfully can be beneficial in helping you manage your weight. Mindful eating involves focusing more on your internal signals of hunger and satiety and less on external signals.

Bringing yourself to the present moment, paying attention to your hunger levels, and slowing down while you eat are all examples of how to be more mindful when eating. Notably, mindfulness-based practices have also been shown to improve the severity of depressive symptoms.

Increasing Activity

Incorporating physical activity into your lifestyle not only helps manage weight but is good for your overall health. Consider joining a gym, taking up a sport, climbing around on the jungle gym with your kids, or walking your dog.

On top of reducing the risk of type 2 diabetes, stroke, high blood pressure, and other health issues, exercise has also been shown to reduce symptoms of depression.

Switching Medications

It's possible that a healthcare provider will be able to prescribe a new SSRI that doesn't cause weight gain, or they may have you try a non-SSRI antidepressant such as Wellbutrin (bupropion), a norepinephrine-dopamine reuptake inhibitor (NDRI). Wellbutrin works differently in the brain than SSRIs do, and some people even lose a little weight while taking it. 

A Word From Verywell

While dealing with some weight gain as a result of your antidepressant medication might be frustrating, don't forget that you're taking a positive step in getting help for yourself by seeking mental health treatment.

Side effects of medications are a reality, but you can always work with a healthcare provider to find the best antidepressant for you. Just remember that this process could take a few tries, so don't get discouraged. Along the way, focus on making healthy lifestyle choices, and applaud yourself for taking care of your mental health.