I'm not sure if the pills are the reason. You need to have more fruits and vegetables in your diet and cut down on cereals and other carbs, start a frequent feed small quantity eating habit. Drink atleast 3lts of water per day. Having green tea a few times around the clock would help.
It is preferable if you visit a dietician and get a proper diet chart according to your lifestyle, eating habit and previous health record.
Coupling the diet with some daily running and abdominal exercises will yield good results.