Wondering which antidepressants cause the most weight gain? A new study of eight first-line antidepressants offers some answers.

“Although there are several reasons why patients and their clinicians might choose one antidepressant over another, weight gain is an important side effect that often leads to patients stopping their medication,” Dr. Jason Block, senior author of the study published Tuesday in Annals of Internal Medicine, said in a statement.

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Block and other researchers at the Harvard Pilgrim Health Care Institute in Boston examined the electronic health records of more than 180,000 patients who were first-time antidepressant users, tracing their weight changes over the course of a year.

At six months, patients taking escitalopram (Lexapro), paroxetine (Paxil) and duloxetine (Cymbalta) had gained approximately 1 pound more than people taking sertraline (Zoloft), the most commonly prescribed antidepressant. These patients also were 10-15% more likely to gain at least 5% of their baseline weight than Zoloft users.

Patients taking bupropion (Wellbutrin) gained the least amount of weight compared to people on other antidepressants and were 15-20% less likely to gain a clinically significant amount of weight than those taking Zoloft. 

Approximately 14% of U.S. adults report taking antidepressants.

“This study provides important real-world evidence regarding the amount of weight gain that should be expected after starting some of the most common antidepressants,” Joshua Petimar, the study’s co-author and a Harvard Medical School assistant professor, said in a statement. “Clinicians and patients can use this information, among other factors, to help decide on the right choice for them.”

Patients whose medical records were used in the study ranged in age between 21 and 79.