In a word... No. There are studies on this and while there are tricks to cause local fat mobilization from particular areas the degree is so small it is basically zero. You store fat in a genetically and hormonally expressed way and you will lose fat in the same way. Doing endless sit-ups or crunches or any other "core" work will not, I repeat WILL NOT cause you to get lean in the midsection. Only by controlling calories consistently over time will you get that lean body of your dreams.