OK, here's the whole thing: #1, everybody has a sixpack, but as soon as there is a body fat percentage of much over 10%, it stops being visible. That's the bottom line. You can do 5,000 crunches a day for 50 years, and you will never have a visible sixpack until you get the body fat level down to where you can see your abs.
The question is, how much priority do you put on rocking that sixpack? If you want it badly enough, you will have it. Everybody has a different metabolism and hormone balance, so you have to figure out what works for you. #1 is to cut out ALL fried foods, and cut out salad dressings that have oil or milk in them (lo fat Italian is OK). Cut out milk chocolate (dark chocolate is OK in moderation).
And here is the kicker, which I'm sure some people will call me out on: EAT at least 5 moderate sized meals a day, with the biggest heaviest one being first thing in the morning. Eat plenty of fat-free snacks (granola bars, fruit, etc), so that your stomach is always with food in it. When you constantly are eating, your metabolism changes in a way that it will not store fat as much, since you are showing it that famine is unlikely, and you need not store anything. If you skip meals, or eat NOT on a regular timed schedule, your body will respond by storing lots of fat; even at the cost of taking energy away from you to be stored as fat! That's because in nature, you might fall on hard times and not be able to eat for a week, and you'd need all that fat to live on. Eat balanced, including red meat, chicken and grain. Go very low on the bread & cereal (carbohydrates). Lean red meat, or eggs, would be a good choice for breakfast & lunch. And the last tip on eating, is stop eating anything about 3-4 hours before bed. What you eat within 3 hours of bet, will be converted to fats and stored on the body. When you want that bedtime ice cream, ask yourself if that's more important than lifting your shirt next summer and having people say "Whoa... How'd you do that?"
Charles
I'm not a dietician or a doctor, but I have managed to keep a great sixpack even now at age 45... So I must not be too mistaken about how to do it . In the picture, I have appx 4.8% body fat.