I always feel pain in my chest.ifeel lethargic.i m putting on weight despite consuming non fatty meals.plz advise.

Many issues: Cannot diagnose you over the internet. It does not matter much whether you are eating non fatty meals. The issue is intake vs. Output. You need to eat 3 meals a day leaving the table satisfied but not stuffed, and exercise regularly. Get a pedometer and make sure you do 10k steps a day at a minimum. Pain in chest definitely demands a doctor's visit and evaluation asap.