You will lose body fat by doing interval training and proper nutrition. By simply avoiding one food group only sets you up for putting the weight back on when you start eating the foods you've cut out. Are you never going to eat carbs the rest if your life?Get a heart rate chart that shows target heart rate to burn fat.
Carbs with a large surface area take longer to break up and are thus "better" because they dont turn into sugar right away. Thats the deal with whole grain. Its not crushed so it has to be broken down in your system which uses energy (callories).