An overview of which antidepressants do or don’t cause weight gain

The 3 most common questions I get regarding antidepressants are 1) are they addictive; 2) how long do they take to work; and 3) do they cause weight gain? (See this post to answer if they are addictive, and this post to see how long they take to work).

Weight gain is unfortunately not a rare occurrence with antidepressants. The exact rate is difficult to establish. Some will say that weight gain with antidepressants will occur in around 25% of patients, but some estimates can be as high as 65% of patients. The truth is that we don’t know the exact rate, and that it will vary by antidepressant. If weight gain does occur, studies have shown this to be a significant cause of people giving up and stopping their treatment. So, it’s important to talk about this openly.


How do antidepressants cause weight gain?

There are different mechanisms that can account for weight gain with antidepressants:

Increased appetite

This one doesn’t require any more explanation. If you are hungrier, you will eat more. If you eat more than you need to, it can lead to weight gain.

Reduced satiety

In plain English, this just means that you don’t get full as quickly after eating. So, if you don’t feel full, you will keep eating (more than you actually need to).

Increased carb cravings

While carbohydrates (also referred to as carbs) are not inherently bad foods, there are many high carbohydrate comfort foods that have almost no nutritional value to speak of (e.g. potato chips). Ingesting more of these empty calories will inevitably lead to weight gain.

Changes to metabolism

There are a few different mechanisms for this one. First, some may lower blood sugar levels; which will then trigger your body into being hungry (which will make you eat more). Second, some may actually affect how your body stores energy; some antidepressants can impact the amount of fat that your body will use to store energy from food.

Efficacy of the medication

If someone was struggling with reduced appetite as a symptom of their mental illness, then once they feel better they may regain their appetite. So, this weight gain may actually just be getting them back to their “normal” body weight.


Slight weight gain over the years is normal

It’s also important to note that weight gain with aging is common. It’s estimated that the average person will gain approximately 1-2 lbs every year. These normal and expected changes in weight may sometimes be attributed to antidepressants. As I’ve said before, correlation doesn’t always equal causation (read this post for more details on that). While antidepressants can cause weight gain, it’s also not 100% of the time either.


Which antidepressants can cause weight gain?

I’ve taken the liberty to create the following tables for each class of antidepressant (if you wanted to compare them side by side or get a bit more information for specific classes):

Selective serotonin reuptake inhibitors (SSRIs)

AntidepressantEffect on weight?
Citalopram
(Celexa)
Weight gain can occur
Escitalopram
(Cipralex)
(Lexapro)
Weight gain can occur
Fluoxetine
(Prozac)
Weight gain less likely
Fluvoxamine
(Luvox)
Weight gain less likely
Paroxetine
(Paxil)
Weight gain is common
Sertraline
(Zoloft)
Weight gain can occur
**This table is only a general summary

Initially, SSRIs may actually reduce weight. But this effect tends to only last for the first few months.

Long term, weight gain can occur in some people. This is thought to be from increased appetite and also from carbohydrate cravings (serotonin has a role in weight/appetite management).

Citalopram and paroxetine seem to be the most likely to cause weight gain in this class of medications. Fluoxetine and fluvoxamine seem to be the least likely to cause it.

For more information on SSRIs, check out my other article here.


Serotonin-norepinephrine reuptake inhibitors (SNRIs)

AntidepressantEffect on weight?
Desvenlafaxine
(Pristiq)
Weight gain can occur
(less than SSRIs)
Duloxetine
(Cymbalta)
Weight gain can occur
(less than SSRIs)
Venlafaxine
(Effexor)
Weight gain can occur
(less than SSRIs)
**This table is only a general summary

Like what is seen with SSRIs, initially the SNRIs may actually reduce weight.

But eventually they can be associated with some weight gain when you look more long-term (due to the same mechanisms as we see with the SSRIs). However, compared to SSRIs, these agents tend to be associated with less weight gain than with SSRIs.


Tricyclic Antidepressants

AntidepressantEffect on weight?
Amitriptyline
(Elavil)
Weight gain
is common
Clomipramine
(Anafranil)
Weight gain can occur
Desipramine
(Norpramin)
Weight gain less likely
Doxepin
(Sinequan)
(Silenor)
Weight gain can occur
Imipramine
(Tofranil)
Weight gain less likely
Nortriptyline
(Aventyl)
(Pamelor)
Weight gain can occur
**This table is only a general summary

All tricyclic antidepressants can cause weight gain. This is caused by both increased food intake and also due to metabolic changes that can occur.

Certain tricyclic antidepressants have a very high weight gain potential (amitriptyline seems to be the worst), while other members of this class (e.g. imipramine and desipramine) seem less likely to cause weight gain.

Amitriptyline can also be associated with many other side effects, such as dry mouth, constipation, and drowsiness; so it’s not often used for depression these days.


Serotonin modulators

AntidepressantEffect on weight?
Trazodone
(Desyrel)
Neutral
Vortioxetine
(Trintellix)
Neutral
**This table is only a general summary

These 2 agents technically act in on the same neurotransmitter (serotonin), however they do it in different ways. But, since they both work on serotonin, they get lumped into the same category of serotonin modulators.

Trazodone has been around for a long time, and is generally considered to be a weight neutral agent. However, due to its high likelihood of causing drowsiness, it has fallen out of favor as a primary treatment of depression. Now it’s often used as an add-on agent to help for sleep and also to augment the effect of other treatments.

Vortioxetine is a newer agent, but in studies done to date it doesn’t seem to impact weight in any significant way (i.e. considered weight neutral).


Atypical antidepressants

AntidepressantEffect on weight?
Bupropion
(Wellbutrin)
Weight loss
Mirtazapine
(Remeron)
Weight gain
is common
**This table is only a general summary

Atypical antidepressants include different agents that generally don’t fit into other classes.

Bupropion is usually associated with weight loss. Due to this effect, it’s actually combined with another drug (naltrexone) in a combination drug called Contrave, which is used as a weight loss treatment.

Mirtazapine, on the other hand, is often associated with weight gain. Due to its very high likelihood of causing drowsiness, it has fallen out of favor as a primary treatment of depression. Now it’s often used as an add-on agent to help for sleep and also to augment the effect of other treatments.


Monoamine oxidase inhibitors (MAOIs)

AntidepressantEffect on weight?
Moclobemide
(Manerix)
Neutral
Phenelzine
(Nardil)
Weight gain
is common
Tranylcypromine
(Parnate)
Weight gain
less common
**This table is only a general summary

MAOIs are not frequently used, due to an increased risk of severe toxicity if mixed with other medications (or even certain foods). However, they can still be effective treatments for some patients.

Phenelzine is highly associated with weight gain, whereas tranylcypromine seems to be less associated with weight gain. The newer member of this class, moclobemide, seems to be weight neutral (or even associated with very slight weight loss).


Tips to deal with weight gain from antidepressants

Speaking as someone who takes an antidepressant, you generally don’t want to stop taking something if it’s helping you function properly. So, if ever there is weight gain from an antidepressant, its important to have tips on how to deal with it.

Here are some different strategies that could be used to help deal with weight gain from antidepressants:

Eat more (real) fruits and vegetables

Many people aren’t aware that Canada’s Food Guide recommends that half of every meal/snack that you eat should be fruits and vegetables. Following this simple piece of advice will help reduce the amount of calories you ingest during a day, while also giving you many more nutrients. As a bonus, all the added fiber found in these foods will help keep you full longer than if you were eating more processed foods.

Track your food intake

The simple act of tracking what you are eating has been shown to help lose weight. There are many apps available to help with this; the 2 most popular seem to be:
MyFitnessPal: available as a free app to log food and exercise, or as a (paid) premium service. The free version seems to be sufficient for most people.
Noom: available as a free app to help log food and exercise. It’s also available as a paid premium service. The premium service adds stuff like one-on-one coaching, and also psychological support in the form of courses and support groups.

Don’t eat while watching TV

Eating while watching TV can often result in overeating. Try to avoid doing this if possible!

Exercise

I know, this isn’t exactly ground-breaking advice. While exercise alone will rarely achieve significant weight loss… it can at least help. As a bonus to being good for physical health, exercise has been shown to help mental health. So, even if it doesn’t help you lose weight, you’ll at least potentially feel better.

Change the antidepressant

If ever you feel discouraged and can’t seem to drop the weight that was gained, it’s also a reasonable choice to consider switching to a different antidepressant. If you had weight gain from one, it doesn’t always mean you will from another.
Note: changing/stopping an antidepressant should always be done in consultation with your care providers (e.g. doctor, pharmacist, etc).


Final thoughts

Many antidepressants can be associated with weight gain. However, some don’t impact your weight, and a few can actually cause weight loss.

If you do experience weight gain from an antidepressant, there are actions you can take to try to lose the weight. Otherwise, it’s always an option to switch to a different medication (in consultation with your care providers).

If you found this post useful, please consider sharing it on social media. There is a lot of health misinformation on the internet; help me reach more people in order to spread reliable information!

Sources:
– RXFiles (08-2021)
– Gill H, et al. Antidepressant Medications and Weight Change: A Narrative Review. Obesity (Silver Spring). 2020 Nov;28(11):2064-2072. doi: 10.1002/oby.22969. Epub 2020 Oct 6.
– Wharton S et al. Medications that cause weight gain and alternatives in Canada: a narrative review. Diabetes Metab Syndr Obes. 2018; 11: 427–438.
– Lexicomp – Drug monographs (08-2021)

Dan Landry

Daniel (Dan) Landry, founder of Rxplanation.com, is an infectious diseases pharmacist at the Dr-Georges-L.-Dumont University Hospital Centre in Moncton, NB, Canada.

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