Lexapro may cause weight gain because it blocks the serotonin transporter, which increases levels of serotonin in the brain, but also increases appetite and decreases metabolism. Research has shown approximately 40% of people taking antidepressants such as Lexapro will gain 7% or more of their starting body weight. The weight gain experienced with Lexapro is a lot less than that reported with other antidepressants such as paroxetine, mirtazapine, or doxepin but more than fluoxetine.

This equated to an average weight gain of approximately 0.65kg (less than 1/3 of a pound) over 12 weeks in one study.

When starting antidepressants, make sure you also increase the amount of exercise you do daily and watch what you eat – ensure your meals contain a lot of vegetables and avoid highly processed fast foods. Speak with a nutritionist or a healthcare professional that can give you good dietary and fitness advice. Studies have also shown that people who smoke are more likely to gain weight while taking an SSRI such as Lexapro.

Monitor your weight regularly once you start taking Lexapro and tell your doctor if you notice weight gain of a pound or two within a short period. It is often easier to reverse weight when the gain is small. Stopping Lexapro may not be the answer to weight gain as it tends to occur with most antidepressants, but it is something that could be considered, although it may not necessarily reverse the weight gain. Your blood sugar levels, lipids, blood pressure, and waist circumference should also be checked regularly after starting antidepressants.