If you want to know how to live to be 100, take a diet tip from the world's oldest man: don't eat so darn much. Walter Breuning turned 113 in September and has weighed a slender 125 pounds for the last 35 years. So what's his secret for staying so slim? Walter says he hasn't eaten dinner for decades. Instead he eats big meals at breakfast and lunch, snacks on fruit all day, and drinks tons of water. It looks like Walter's got more than 100 years of experience to back him up! A recent Harvard study found that people who eat the most produce have brains two years younger than their actual age. To make sure you're getting the most out of your fruits and veggies, the folks at Prevention magazine say eat from each of the five color groups. Meaning red, white, green, orange-yellow, and blue-purple. Like strawberries, cauliflower, leafy greens, peaches, and especially blueberries! What about all that water that Walter drinks? Well, researchers at the University of Utah found that people who drank eight glasses of water a day had higher metabolic rates than those who had only four glasses. All of your body's chemical reactions - including your metabolism - depend on water. So if you're not knocking back water like Walter does, make it a routine to drink one glass before you eat any meal or snack. *Walter also skips dinner and eats larger meals earlier in the day. While most diet plans say to eat small meals every few hours, Walter's way might not be that bad. According to nutrition experts, short fasts, like skipping dinner, make your body better at regulating blood sugar. Research shows, that most fasters will eat more at their next meal, BUT not enough to make up for the calories they missed. Walter says the secret to a long, healthy life isn't just diet; it's keeping your mind and body occupied. Walter worked for the Great Northern Railroad for 50 years, and then managed the local Shriners club until he was 99. To this day, he listens to the radio to keep himself sharp and he spends a lot of time talking with visitors at his retirement center, who all come by to meet the world's oldest man.