Most of us have to carefully count calories and convince ourselves that salad is rewarding if we want to avoid obesity. Not so for Olympic-level endurance athletes like distance runners, cyclists, triathletes, and swimmers, who burn through calories so fast they have to consume piles of junk food to ensure they have enough fuel in the tank. So instrumental is food to an Olympian's success that many Muslim participants are planning to postpone their annual Ramadan fasts when the games begin on Friday. Here, a guide to the "insane" diets of Olympic athletes:

How fast do athletes-in-training burn through calories?
Lickety-split. Normal people are told to consume roughly 2,000 calories or less a day. But elite athletes can burn through 15 to 20 calories in a single minute, Dr. Michael Joyner tells The New York Times. At the peak of their training, athletes work out for four or five hours every day, which means they'll have to replenish some 4,000 to 6,000 calories if they want to "train again the next day." 

What are they eating?
In 2008, gold-medal-winning swimmer Michael Phelps made headlines when details of his 4,000-calorie breakfast were made public: Three fried-egg sandwiches, a five-egg omelet, a bowl of grits, three slices of French toast, and three pancakes with chocolate chips. Indeed, a typical meal for endurance athletes can resemble an episode of Man v. Food, says Gretchen Reynolds at the Times. An athlete might sit down for dinner and inhale a pound of pasta cooked with olive oil (800 calories), a dozen eggs (840 calories), an entire cheese pizza (2,000 calories), a pint of Ben & Jerry's cheesecake-brownie ice cream (1,000 calories), and beer (about 150 calories per bottle). 

Why not eat healthy food?
"You can only eat so much oatmeal and tofu," says Dr. Joyner. And the calories don't add up. A bowl of oatmeal gives you just 150 calories, while a cup of tofu only boasts 175. But processed junk foods — candy bars, cookies, Pop-Tarts — provide more energy-replenishing calories per gram. Even when restricting their diet to pizza and ice cream, some athletes still shed weight. Of course, not everyone agrees with Dr. Joyner. Here's an example of a healthy 6,000-calorie diet for high-endurance Olympic athletes that relies on lean meats, whole grains, and low-fat dairy. Of course, it requires athletes to eat six times a day.

Could I eat like this, too?
If you work out like crazy, then why not? "The overwhelming body of science" about weight loss and food "continues to show that any diet will succeed if you take in fewer total calories than you burn," says Dr. Dena Bravata, a food researcher from Stanford. "Large quantities of pizza? Ice cream? Beer?" says Dom Consentino at Deadspin. "That settles it. My own quest for the 2016 Olympics begins tonight."

Sources: Deadspin, ENI News, New York Times, Newser, NPR