Read this post in the pinned Mythbuster thread:
http://forum.lowyat.net/index.php?showtopi...post&p=23708601

Start increasing your energy usage by doing labour work, exercise, cardio, resistance training or all of the above.

And come join us in the bodybuilding thread. Don't be afraid to get flamed. At least you'll learn a lot of things. =P

What's your height?

>>Cardio? Do you mean by running and so on? I play tennis 2 times a week duration for 1 hour and is that sufficient? Currently I'm doing 30 times sit up in the afternoon and in the night, is that enough to see 6 packs in like 3 months?<<

More like 300 times twice a day, if you insist on this particular sort of cardio.

That's not an excuse.

HIIT is a good form of cardio and it doesn't take all day either. There is no such thing as spot reduction, so doing a thousand sit-ups a day won't necessarily get rid of all the fat covering your abs, but it'll definitely wear you out and possibly give you a sore back. You need cardio, like it or not, to burn fat. Replace the sit-ups with crunches and add in planks to your ab routines as well.