By Dan Friedell, USA TODAY

The average adult male who weighs 150 lbs. requires about 2,000 calories per day to sustain his body weight. Factor in a half-hour of vigorous exercise, and that number increases by about 10%. If he's running a marathon, that number more than doubles.

Consequently the world-class runners who are converging on New York City this weekend must spend about as much time eating each day as they do training for the marathon. We asked three American runners: Miguel Nuci, Jason Lehmkuhle and Meb Keflezighi to keep track of what they ate during a typical training day in October.

Each runner has a different quirk. For instance, Keflezighi, the 2004 Olympic silver medalist and a native of Eritrea in East Africa, likes to work a traditional Eritrean meal made with chicken and a homemade Eritrean bread into his eating plan. Lehmkuhle, who once drove himself crazy weighing and measuring everything he ate, now eats whatever he wants and lets the 150 miles he runs per week burn off oatmeal-chocolate chip cookies and pints of Ben and Jerry's ice cream. Nuci, who makes sandwiches all day at Togo's in his hometown of Turlock, Calif., takes advantage of the easy access to carbs and protein with which he fuels his runs.

Lehmkuhle jokes that the guys at his neighborhood Super America convenience store know him by his first name, since he's a regular late-night visitor to the bakery case. Nuci, who qualified for the Olympic trials race while still a Mexican citizen, enjoys going out once a week with his wife for an authentic meal of enchiladas or camarones a la diabla (shrimp in spicy sauce).

All three athletes share the common characteristic that they have notched a sub-2 hour, 20 minute marathon within the last two years, but they fuel up in distinct ways. See their food logs below:

From weighing every gram of protein to measuring half-liters of water, Olympic-hopeful marathoners can take preparation to an extreme. Others decide that ultra-long training runs require massive calorie consumption, so it's quantity over quality. USA TODAY asked three American Olympic team contenders in the marathon to keep track of what they ate on a typical training day while preparing for Saturday's Olympic Trials in New York City.