Knowing what to eat while getting your six pack is absolutely essential. Without it, you'll never get the results you're looking for. And why is this? Because 99% of people trying to get a six pack can't get one because their body-fat percentage is too high. This diet will help you slim down, while still putting on muscle so when your skinny enough you'll have a nice, visible six pack to show for it.
I will summarize this diet through three keys.
1) Low fat high protein meals are necessary.
This is true for absolutely everyone. Protein helps build the muscle you need to maintain toned abs. Without it, your workouts are much less effective. You will still see some results without it, but adding it to your diet will quicken your progress.
2) Cut down on the carbs.
For almost all people this is true. Only a small amount of people actually have a low enough body fat percentage to not cut back on the carbs. You eliminate the carbs, you start to trim down on your waste line, and you start to see results. This is the main reason why people who complain about not having a six pack don't actually have one.
3) Eat your fruits and vegetables.
Easily put, not so easy to do. They simple provide the right vitamins and minerals your body will need for muscle growth. They're low in fat and many are high in protein so you can see why they're an important aspect.
These should get you covered with the basics. If you are serious about getting your six pack and would like more tips/info you can visit my Quick Six Pack website for more info.