Haven't eaten well since i was put on sertraline. how could weight gain be a side effect of sertraline when i don't even have an appetite?

Appetite changes: Are seen in patients on ssris. Can be either direction and may be different with another drug in the class. Nausea in first 2 weeks usually gets better. If it is longer talk to your doctor about a change.

Be patient : Early side effects to medication may not last beyond few weeks. People respond differently to medication, not 100% of people will gain or lose weight on a medication. Your doctor is best to know your condition and follow up on the issue then decide what is the best course of action to help you.