How much food does a runner need?
Consider everyone’s favorite “F” word: fuel. On the surface, it’s a simple concept -- eat enough throughout the day to power your body. But determining ideal caloric intake is tricky business. Get it right, and you’ll supercharge your running. Get it wrong, and you may sabotage your training.
Several factors influence how many calories a person needs per day, including age (young runners require more), and gender (women need fewer). Things are further complicated by natural variations in metabolic rate -- some people are simply born calorie-burning machines. Even living in an especially cold or hot climate can influence fueling needs, since a body in one of these environments requires more energy to maintain proper temperature.
Here’s the good news: We can still estimate a runner’s daily caloric need through a series of Good Will Hunting-style calculations (Do you like Apples? Well I got her number, how do you like them apples). Most nutritionists consider the BMR, or basal metabolic rate, a good jumping-off point. This number represents the amount of calories a body needs simply to exist – so… lying in bed, doing nothing, after at least a 12-hour fast.
For men, that calculation looks like this: BMR = 10 x weight (in kilograms) + 6.25 x height (in centimeters) - 5 x age (in years) + 5.
For women, that calculation looks like this: BMR = 10 x weight (in kilograms) + 6.25 x height (in centimeters) - 5 x age (in years) - 161.
And for people who’d rather not crunch numbers, that calculation can be done by a computer.
Of course, runners don’t spend all day lying in bed doing nothing (recovery days spent binging Ozark notwithstanding). And all additional activity requires additional fueling. A formula for building on the BMR calculation to determine total energy expenditure exists, but it requires labeling your running routine according to one of several vague categories. (A “lightly active” person, for example, is someone who engages in “light exercise” -- a fairly subjective phrase -- 1-3 days per week.)
Some experts offer more cut-and-dry recommendations for runners. Runner’s World offers a calculator that determines calories burned on a specific run, so that this number can then be added to the BMR on a daily basis, to discover total calorie expenditure. (Wearing a heartrate monitor that tracks calorie burn is also an option.) And the Rock and Roll marathon series suggests consuming between 19 and 21 calories per pound of bodyweight for one to one-and-a-half hours of running per day; 22-24 calories per pound for one-and-a-half to two hours of running; and 25-30 calories per pound for two to three hours of running.
It’s important to remember that not all calories are created equal. No amount of calculations will help your running routine if your diet consists mainly of marshmallows and Mountain Dew. In fact, chronically consuming empty calories can increase the inflammation that will sabotage a running regime, BMR bedamned. On the flip side, the more nutrient dense the fuel (cough, Trishmoves, cough), the healthier -- and happier -- you’ll be.