Antidepressant Use May Be Linked With Sustained Risk for Weight Gain

Long-term antidepressant use was associated with a sustained increase in weight gain lasting at least 5 years, according to research published in The BMJ.1

Patients taking any of the 12 most common antidepressants were more likely to gain weight compared with patients who were not taking the medications. This risk was greatest during the second and third years of antidepressant treatment.

A research team based in the United Kingdom led by Rafael Gafoor from King’s College London used data from the UK Clinical Practice Research Datalink (CPRD) to analyze body weight and body mass index (BMI) in more than 300,000 adults (mean age 51; 136,762 men, 157,957 women) whose BMI had been recorded 3 or more times during general practitioner consultations from 2004 to 2014.

Participants were grouped according to BMI (normal weight to severely obese) and according to whether or not they had been prescribed an antidepressant in a given year.

To estimate adjusted rate ratios, researchers used a Poisson model adjusting for age, sex, depression recording, comorbidity, co-prescribing of anti-epileptics or antipsychotics, deprivation, smoking, and advice on diet. The participants were monitored for 10 years.

The researchers found that in patients taking antidepressants, the absolute risk of gaining at least 5% weight was 9.8 per 100 person years compared with a risk of 8.1 per 100 person years in patients not taking antidepressants. In other words, for every 59 people taking antidepressants, 1 extra person would gain at least 5% weight during the study period.

The researchers found this risk to be greatest during the second and third years of treatment: in the second year of treatment, the risk of gaining at least 5% weight was 46% higher than in the general population.

No association was found during the first 12 months of treatment.

In individuals taking antidepressants, individuals who were originally a normal weight had a higher risk of moving to the overweight or obese groups, and individuals who were initially overweight had a higher risk of moving to the obese group.

After taking into account factors including age, sex, and whether the participants had other conditions such as diabetes, stroke, and cancer, these findings remained largely unchanged.

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The researchers noted that this was an observational study, and therefore no conclusions can be drawn as to cause and effect; limitations of the study could have also affected the results. However, the strengths of the study include a large number of participants and long-term follow-up.

“Widespread [use] of antidepressants may be contributing to long-term increased risk [for] weight gain at [a] population level,” the researchers concluded. “The potential for weight gain should be considered when antidepressant treatment is indicated.”

“Currently, we are still unable to identify patients at higher risk of weight gain with antidepressants,” noted the authors of an accompanying editorial, Alessandro Serretti and Stefano Porcelli from the University of Bologna, Italy.2 “Hopefully it will be possible in the not too distant future to identify a genetic predisposition and [recognize] those at higher risk before treatment is started.”

They noted that while antidepressant treatment should always be offered to patients with moderate or severe depression, alternative treatment such as group cognitive behavioral therapy may be preferable in patients with milder depression.

However, Dr Gafoor noted, “It’s important to stress that no patients should stop taking their medication, and that if they have any concerns they should speak with their doctor or pharmacist.”


  1. Gafoor R, Booth HP, Gulliford MC. Antidepressant utilisation and incidence of weight gain during 10 years’ follow-up: population based cohort study [published online May 23, 2018]. BMJ. doi:10.1136/bmj.k1951
  2. Serretti A, Porcelli S. Antidepressant induced weight gain [published online May 23, 2018]. BMJ. doi:10.1136/bmj.k2151