Short-term studies suggest antidepressants are associated with modest weight gain but little is known about longer-term effects and differences between individual medications in general clinical populations: some of the drugs are linked to more weight gain than others.
Objective of this study was to estimate weight gain associated with specific antidepressants over the 12 months following initial prescription in a large and diverse clinical population.

Researchers identified 22,610 adult patients who began receiving a medication of interest with available weight data in a large New England health care system, including 2 academic medical centers and affiliated, outpatient primary and specialty care clinics and they used electronic health records to extract prescribing data and recorded weights for any patient with an index antidepressant prescription including amitriptyline hydrochloride, bupropion hydrochloride, citalopram hydrobromide, duloxetine hydrochloride, escitalopram oxalate, fluoxetine hydrochloride, mirtazapine, nortriptyline hydrochloride, paroxetine hydrochloride, venlafaxine hydrochloride, and sertraline hydrochloride.
As measures of assay sensitivity, additional index prescriptions examined included the antiasthma medication albuterol sulfate and the antiobesity medications orlistat, phentermine hydrochloride, and sibutramine hydrochloride.
Mixed-effects models were used to estimate rate of weight change over 12 months in comparison with the reference antidepressant, citalopram.

Clinician-recorded weight at 3-month intervals up to 12 months.

The results showed that people taking citalopram (Celexa), from a class of antidepressants known as selective serotonin reuptake inhibitors, or SSRIs, gained more than two and a half pounds, on average.

Other SSRIs were associated with weight gain similar to citalopram, with people taking fluoxetine (Prozac) gaining on average a pound and a half and those taking sertraline (Zoloft) gaining nearly two pounds, the authors write in JAMA Psychiatry.

On the other hand, people taking bupropion (Wellbutrin) lost on average nearly half a pound. The tricyclic antidepressants nortriptyline and amitriptyline were also linked with significantly less weight gain than the SSRIs.

See also
Can antidepressants cause weight gain? (23/07/2010)

For more information
An Electronic Health Records Study of Long-Term Weight Gain Following Antidepressant Use (with the "Conflict of Interest Disclosures")

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