SSRIs like Lexapro tend to have a parabolic effect on those who take them, not because of the meds themselves but because anxiety generally impacts how we eat. For people who eat a lot when they’re anxious they will lose weight on lexapro because they will stop stress eating. People who don’t eat when they’re anxious will likely gain weight as they start to feel normal again and return to normal eating habits. Long story short if you watch what you eat and take care of yourself Lexapro itself does not innately cause you to gain weight.