Do SSRIs cause carb cravings? (What the science says)
I gained weight while I was on Citalopram and Lexapro for over a decade and have posted about this gain before but I’ve been noticing a lot of posts specifically about carb cravings on SSRIs. It made me curious about why these cravings happen, so I looked into the science (I have a BSc in Anatomy with Biochemistry) and found out a few things I want to share with everybody.
The simple answer: It’s not a lack of willpower but likely a biochemical feedback loop your brain has built.
Why this Happens
Months 1 to 6: Your fullness signalling starts to fade
SSRIs increase serotonin by preventing it from being reabsorbed between nerve cells. In the short term this stimulates receptors in a part of the brain called the hypothalamus which are responsible for signalling fullness when you eat. This is why many people notice reduced appetite in the early weeks of treatment.
But with prolonged use the stimulation causes the receptors to desensitise and downregulate. When this fullness signalling weakens, your appetite increases and the brain may begin looking for serotonin from another source.
The Loop: Carbs - Insulin - Serotonin
Serotonin is made from tryptophan, but tryptophan has to compete with other amino acids to cross the blood brain barrier. Carbohydrates help with this: they trigger an insulin release, which clears competing amino acids from the bloodstream, giving tryptophan easier access to the brain. So more tryptophan getting in - leads to more serotonin being synthesised - which leads to temporary relief - and this in turn reinforces cravings.
This tryptophan-carbohydrate link is well established science from MIT research going back to the 1970s and is still being studied.
So the full loop looks like this:
SSRI use → receptor desensitisation → fullness signalling drops → brain seeks serotonin via food → carbs trigger insulin → tryptophan floods the brain → serotonin rises → craving is reinforced - and the process repeats*.*
How this Differs by SSRI
The effect isn’t the same across all SSRIs - weight and appetite changes vary quite a bit depending on which one you’re taking.
At the higher end, paroxetine (Paxil/Seroxat) and escitalopram (Lexapro/Cipralex) are the two most associated with weight gain. A 2024 Harvard study of over 183,000 patients found both carried a 10-15% higher risk of clinically significant weight gain compared to sertraline, with escitalopram slightly ahead on average weight gained. Citalopram (Celexa/Cipramil) sits in the middle - there is evidence specifically linking it to carb cravings early in treatment, though its overall weight gain in the Harvard study was less than paroxetine or escitalopram.
Sertraline (Zoloft/Lustral) is lower risk and fluoxetine (Prozac) is generally considered the most weight-neutral SSRI in the class - the study found no significant difference in weight change between fluoxetine and sertraline. Fluvoxamine (Luvox) is relatively weight-neutral but is used mainly for OCD, so the long-term data is thinner.
That said, it’s important to remember that not everybody experiences appetite or weight changes on SSRIs and for many people the benefits far outweigh the downside. This was true for me despite the weight gain I experienced.
The Key Takeaway
If you’re craving carbs on an SSRI your willpower isn’t failing. Your brain has likely lost a fullness signal it depended on and it’s compensating by using a hardwired pathway which was around long before SSRIs, so it isn’t imagined and it isn’t a character flaw.
I hope this information helps. Has anyone noticed this pattern? - early appetite suppression followed by cravings months later?
Sources:
-Wurtman & Wurtman (1995) - Brain serotonin, carbohydrate craving, obesity and depression. Obesity Research
-Bouwer & Harvey (1996) - Phasic craving for carbohydrate observed with citalopram. International Clinical Psychopharmacology
-Petimar et al. (2024) - Medication-Induced Weight Change Across Common Antidepressant Treatments: A Target Trial Emulation Study. Annals of Internal Medicine. Harvard Medical School & Harvard Pilgrim Health Care Institute
-Mouawad, Nabipur & Agrawal (2025) - Impact of Antidepressants on Weight Gain: Underlying Mechanisms and Mitigation Strategies. Archives of Clinical and Biomedical Research
(All these studies are available via PubMed for anyone who wants to do a deeper dive)
Please note that this is educational information only - never adjust medication without speaking to your doctor.