There are many factors for weight gain. First question is for how long have you been taking escitalopram for?
Weight gain can also be there because of depression itself, and even escitalopram can cause weight gain.
But the positive side is that can be controlled if you do some lifestyle modifications including your diet and daily excercise. If you have other comorbidities like hypothyroidism, or you consume alcohol the chances of having weight gain increases.
Next Steps
consider life style changes. consult a dietician or nutrition expert to modify your dietary patterns. consider including some exercises in your daily routine.
even the dose of medication can be considered to be tapered down if weight gain is too much. you should consult your psychiatrist and discuss the options of modifying treatment either by tapering the medication or changing the medication to another with lesser potency for weight gain.
Health Tips
do not taper down medication or change it without consultation with your clinician. consider first lifestyle modifications before treatment modification if the treatment has significantly improved your symptoms.