Longtime readers know I'm constantly tinkering with my diet and my exercise plan because I want to live forever. I've done enough research and experimentation to settle on a Paleo diet and a barbell strength training program. I also run and play sports, but those are done for fun more than any health benefit.
I found a great article laying out the Paleo diet in six easy steps - http://www.gnolls.org/1141/eat-like-a-predator-not-like-prey-paleo-in-six-easy-steps-a-motivational-guide/. His advice is medically sound and jives with everything else I've read. The key to a successful diet is to eat real food. If it isn't something you could kill or gather, then don't eat it. If it requires significant processing to be edible, don't eat it.
This diet has worked well for me and I can tell when I've fallen off the wagon. Last weekend, I was feeling crappy so I got a bunch of crap from the grocery store. I ate cookies, cupcakes, ice cream and other garbage. I enjoyed the sugar high for about a day and then I got the farts and dookers and generally felt crappy. I got back on the wagon on Wednesday and have been doing much better since. Sure, it's just anecdotal evidence, but give it a shot and see how you feel.