The research I've read seemed conclusive that what you eat is as important or more important as how much. Intuitively it makes sense that giving you body the correct building blocks would make it healthier and that's definitely not just a function of quantity. And from what I've read the science supports it as well. Here's a relevant book about it:

http://www.amazon.com/Anticancer-New-Way-Life-Edition/dp/067...