Antidepressant use is generally not linked with changes in body weight, but some recent studies have suggested a positive association between long-term antidepressant use and weight gain. This study aims to examine the long-term association of antidepressant use and changes in body weight.

This is a population-based cohort study that included a total of 136,762 men and 157,957 women with three or more records for body mass index (BMI) scores. The primary outcomes of the study were an increase in body weight and transition to overweight or obesity associated with antidepressant prescribing. 

Out of all participants, 17,803 (13.0%) men and 35,307 women (22.4%) with mean (SD) age 51.5 years were taking antidepressants. During the follow-up of 1,836,452 years, the incidence of new episodes of weight gain in participants prescribed to antidepressants was 11.2 per 100 person-years, compared with 8.1 per person-years in those not prescribed to antidepressants. The adjusted rate ratios in people who were initially of normal weight and overweight were 1.29 for each, respectively.

The research concluded that the use of prescription antidepressants for a long time could be associated with an increased risk of weight gain. Therefore, clinicians should take note of the potential weight gain when prescribing antidepressants.