CNN recently posted an article about a 27-year old trying to get a "six pack" of abdominal muscles for his 10-year reunion.
Tony Gentilcore, a Boston-based trainer, blogged about it on the Boston Herald website. Tony's response is well worth reading. It's packed full of information about this guy's quest. Not the least of which, he's 140# of bodyweight and trying to slim down.
Paraphrasing Mark Rippetoe, this is someone trying to get a six-pack before he's even got a cooler to put it in. Unless this guy is really short, 140# is not a lot. He appears pretty skinny in the pictures, and he's worried about a little more definition. His diet is also very low fat, and his exercises include 150 crunches a day with 25 pounds of resistance. That's a lot of work for a very small muscle group...and working your abs won't burn belly fat. It's called the Spot Reduction Myth. You can scroll down on that linked page at EXRX to see a myth about high reps burning more fat, too.
All in all, this guy's quest seems terribly misguided. The abs have become the big biceps of our day - the central pre-occupation of the average gym trainee. The methods he is using to get there are also sub-optimal.