Many people who are prescribed antidepressants hesitate to take them because of the common side effect of weight gain. In a new study, researchers analyzed eight different first-line antidepressants and identified the drugs that lead to the most weight gain and the ones with relatively lesser impact.

According to the study published in the journal Annals of Internal Medicine, patients who use bupropion have 15-20% less risk of weight gain compared to those who use sertraline, the most common medication.

An estimated 14% of U.S. adults use antidepressants. The weight gain associated with these medications can impact long-term metabolic health, often discouraging patients from continuing their prescribed treatment and leading to poor mental health outcomes.

The latest study conducted by the research team from the Harvard Pilgrim Health Care Institute suggests that although antidepressants are in general associated with weight gain, specific antidepressant medications may affect weight differently.

"Patients and their clinicians often have several options when starting an antidepressant for the first time. 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. Clinicians and patients can use this information, among other factors, to help decide on the right choice for them," lead author Joshua Petimar said in a news release.

The study analyzed electronic health record prescription data from eight health systems in the U.S. comprising 183,118 adults between the ages of 18 and 80. The participants were new users of one of eight common antidepressants: sertraline, citalopram, escitalopram, fluoxetine, paroxetine, bupropion, duloxetine, and venlafaxine. Their weight changes were recorded at 6, 12, and 24 months after starting antidepressant therapy.

Bupropion users gained the least amount of weight compared to users of other antidepressants. They were 15-20% less at risk of having clinically significant weight gain compared to sertraline users. Having a weight gain of 5% or more is considered clinically significant.

Antidepressants within the same class had varying impacts on weight gain. For instance, among Selective Serotonin Reuptake Inhibitors (SSRIs), escitalopram and paroxetine were each linked to an approximately 15% higher risk of significant weight gain compared to sertraline in the first six months.

The researchers also noted that a majority of patients were on an antidepressant linked to greater weight gain than alternatives available in the same class or subclass.

"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. Our study found that some antidepressants, like bupropion, are associated with less weight gain than others. Patients and their clinicians could consider weight gain as one reason for choosing a medication that best fits their needs," said senior author Jason Block.