It seems almost impossible that runners could become overweight. All that running, all those calories burned along city streets and down park paths--it just doesn't seem right (or fair).

The problem is that we read about the performance-oriented nutritional habits of ultrathin elite runners (lots of carbo-loading and truckloads of energy bars, gels, and drinks), then assume that as recreational runners we should do the same. But we're not elite runners. We're average people who use running to manage our weight, increase our energy, and lead healthy lives.

Think about this scary fact: It takes only 100 extra calories a day to gain 10 pounds in a year. That's one high-calorie prerun snack that you didn't need. Or one unnecessary bottle of sports drink before a 30-minute walk. The extra weight many runners carry around is simply the result of eating for energy or performance--with little regard for total calories. But calories do count, and as runners we tend to underestimate the amount we eat and overestimate the amount we burn.

What you need to do is match your eating plan to your running habits. You need to know exactly when to eat those carbohydrate-rich foods that will give you the energy you need to run well.

You also need to know when to consume the lean proteins and heart-healthy fats that will keep you satiated while still losing weight. You need the Runner's Diet.

The Runner's Diet helps you determine the real number of calories you need to maintain or lose weight based on your current running schedule. It's a 50-25-25 eating plan, where 50 percent of your calories come from carbohydrates, 25 percent from protein, and 25 percent from fat. With half of your calorie intake coming from carbs, the diet provides you with plenty of readily available fuel for your runs. And with the rest of your calories split evenly between proteins and fats, you feel full longer, which is key to losing weight. The diet also focuses your carbohydrate intake around your runs and emphasizes the right proteins and fats for all other meals to optimize performance and weight loss. Finally, you'll have lots of choices when deciding what to eat. To start the Runner's Diet, follow this simple, six-step process.

Step 1
Determine Your Daily Calorie Goal

To estimate your daily calorie needs for maintaining your current weight, take your present weight and multiply by 13. That number covers your metabolic needs for the day, factoring in a bit of light activity. So if you weigh 180 pounds, you need about 2,340 calories per day. To lose a pound a week, you must then create a calorie deficit of 500 calories a day (3,500 calories equals one pound).

How many calories you can cut from your diet depends a lot on how much you're eating right now. There's a big difference between cutting 500 calories if you're eating 1,500 a day than if you're eating 3,000. But remember: Weight loss is a lot easier when you factor in your running mileage (1 mile = 100 calories). So your calorie deficit can--and should--be created by eliminating some calories from your daily diet and increasing the number you burn per day through running.

Step 2
Distributing Your Calories

After you've determined the total number of calories you should be consuming per day to meet your weight-loss goals, divide those calories so that 50 percent of them come from carbohydrates, 25 percent come from protein, and 25 percent come from fat. So, for example, if you've determined that your daily calorie goal is 1,800 calories, then 900 of those calories should come from carbohydrates, 450 from protein, and 450 from fat. Remember: You're not striving to have every food you eat meet this ratio. You're simply aiming to get your total daily calorie intake to fall within these guidelines.

Step 3
Selecting Carbohydrates

Lots of runners will look at the 50-percent carbohydrate guideline and think they'll go into macaroni withdrawal. They'll argue it's not enough--that they need 60 percent or more. After all, carbohydrates are the body's preferred energy source.

While it's true that elite runners need a very high percentage of calories from carbohydrates, recreational runners simply don't need as many carbs. Taking in 50 percent of your daily calories from carbohydrate sources will provide you with all the energy you need.

Because high-carb foods sustain you during your workouts, they are best eaten just before and just after your runs. When choosing which carbs to eat, opt for those that are fiber-rich and have a high water content to keep you feeling full.

Step 4
Selecting Proteins

While protein's primary role is maintaining muscle integrity, it also satisfies hunger. Protein provides a greater feeling of fullness, ounce for ounce, than an equivalent amount of carbohydrate. The effect: You're content with fewer calories. That's why 25 percent of your calories should come from protein.

When you choose proteins, lean is always best. Fat adds flavor to protein--but also calories. So be sure to limit the number of calories in the protein sources you choose. A good rule of thumb: The fattier the protein, the smaller the serving.

Step 5
Selecting Fats

Most dieters immediately start cutting fat. But instead of just cutting out junk-food sources of fat, they also cut fatty foods that are healthy, including nuts and nut butters, and olives and olive oil.

Foods with a little fat help slow the rate of digestion and provide a sense of fullness. Try to get 25 percent of your daily calories from good fats by selecting heart-healthy vegetable, nut, and fish sources.

Step 6
Establish an Eating/Running Pattern

The wild card in the 50-25-25 eating plan is how you distribute your calories throughout the day. That depends on your running schedule. Because you want to eat the bulk of your carbohydrate calories around the times when you will be active, you need to know ahead of time when you're going to exercise each day. Then select mostly carbohydrate-rich foods to fuel up beforehand or afterward. By eating most of your carbohydrate calories around your runs, you'll then eat most of your protein and fat calories the rest of the day when you're more sedentary.

Remember one other guideline when establishing your daily eating pattern: Don't go too many hours without eating or your brain will signal starvation mode and stimulate your appetite. So go ahead and have a morning, afternoon, and evening meal, along with snacks. Just make sure that when you tally up all your eating, you're still within your daily calorie range.