Lexapro can cause weight gain, especially with long-term use. Learn why this happens and how to manage this side effect. Lexapro can cause modest weight gain for some people, especially over several months. Others may remain stable or even lose a small amount of weight early in treatment. Lexapro won’t “magically” make you gain weight, but it can decrease your metabolism which can make it almost impossible to maintain or lose as your TDEE isn’t consistent with what you’re able to calculate. Lexapro can cause changes in weight. There are some reports that people begin to lose weight when first taking Lexapro, but this finding is not well supported by research studies. Lexapro does not clinically cause weight loss or gain. It influences your mood and energy and lifestyle - and your reaction to your new normal is what caused changes. Why does Lexapro cause weight gain and what safe switch options exist? Lexapro boosts serotonin, which can stimulate appetite and reduce energy expenditure over time. If you're struggling with depression, the most important question about taking an antidepressant is whether it will work. But another question on your mind may be whether it will fuel weight gain. A new study provides some context. Lexapro (escitalopram) causes modest weight gain on average: about 1.4 pounds at six months and 3.6 pounds at two years, according to data highlighted by Harvard Health Publishing. Lexapro (escitalopram) can cause weight gain, but the amount is relatively modest for most people: about 1.4 pounds at six months and 3.6 pounds at two years, based on a large analysis of electronic health records published by Harvard Health. Lexapro generally causes less weight gain than several other commonly prescribed antidepressants, making it a relatively favorable choice for patients concerned about weight changes.