eat 4 meals a day (heavy breaker, moderate lunch, small snack in evening such as a pear/ apple/ some nuts and very light dinner). Let your daily diet comprise: complex carbs (preferably thru fiber foods such as wheat, oatmeal, fruits), veggies, if non-veg stick to skinless chicken/ fish say 3 times a week, low fat dairy, some nuts like almonds/ walnuts.
Also do high intensity exercise 3 or 4 times a week. For instance repeat the following 8 times after selecting a good running track (could be a park or a track):
1. run as fast as you can for 30 sec.
2. Jog back to starting point at a very relaxed pace
3. Repeat (1 and 2) 8 times
It should increase your metabolism
and help you burn fat long after you have stopped exercising for the day.
Additionally, whenever you get the opportunity to walk (say up the stairs or walk to & fro work), grab it.