Antidepressants and weight gain

This week we take a look at an article published in the BMJ at the end of May 2018. It was a review of antidepressant usage in the UK and the weight gain associated with that medication. There were two outcomes that were the focus of the study: i) to see if there was an association between taking antidepressants and gaining 5% of body weight or more and ii) to see if there was an association between taking antidepressants and moving from one Body Mass Index (BMI) group to the next one up e.g. moving from the overweight category to the obese category.

The article included data from almost 300,000 men and women who were assessed for antidepressant use and weight gain over a number of years. The study usefully listed antidepressants by category (e.g. SSRIs) and singled out some named drugs (e.g. fluoxetine), so anyone taking antidepressants, or who knows someone taking them, will be able to see the impact of a particular drug/drug category.

The most striking things to me were the factoids on people taking antidepressants even before the weight aspect of the study was started. Almost one in five people in the UK were taking antidepressants when selected for this study. Women were almost twice as likely as men to be taking antidepressants. People taking antidepressants were far more likely to be taking other medications that are known to be associated with weight gain.

The study did find an association with taking antidepressants and weight gain. The study was large – 2 million person years of data. For every 100 person years (that’s the measure used in these long terms studies of people) 8 people who weren’t taking antidepressants gained ≥5% body weight vs. 11 people who were.