As a disclaimer I'm not a nutritionist and you have to decide for yourself if this is something worth pursuing.
I went into a large chain bookstore on the other day and noticed two good sized tables full of different books on losing weight. All of them were about trying to make the reader believe that if they followed the eating plan outlined in the books, then they would look great in a swimsuit. I didn't read all of those books so I can't say whether or not their programs were wrong, but in my estimation the focus isn't where it should be.
I don't mean to say that wanting to look better isn't a valid reason to eat better and workout, but it definitely has lead to a lot of ineffective and some borderline dangerous nutrition programs. It's been my experience that when you use your nutrition to improve your performance your health and appearance improve more than if you use a nutrition program solely for improving your appearance and performance declines and sometimes health as well.
So what do we do to eat better to improve performance thereby improving appearance.
First a paradigm shift is required. You have to look at your food choices in the light of performance rather than "will this make my butt big". Second you have to learn what foods improve performance and what foods impede performance. My answer to this 64 million dollar question is based on my personal experience and research, how it has effected me and the people that that have done it. This is taken from CrossFit, "eat meat and vegetables, nuts and seeds, some fruit, a little starch and no sugar". That's it. It's simple and fairly easy. If something isn't on that list I don't eat it. There are far smarter people than me that have written extensively on this. So if you want to check out all the technical stuff check out the book called "The Paleo Diet" and Google a guy by the name of Robb Wolf, he has some amazing writings on nutrition.