Fat. Not so long ago, it was basically a four-letter word. Athletes and experts believed that eating too much of it packed on pounds and drug down performance. Going farther, faster and longer meant making sure you got your three Cs: carbs, carbs and more carbs.
Now researchers are calling this nutritional tunnel vision into question. A growing stack of studies shows that female athletes are better at tapping into their fat stores for energy than men -- and other evidence finds that the nutrient can protect against injuries. To clear up the fat facts, we went to the experts for the skinny.
Fat as fuel
"Athletes are a hybrid engine, burning both carbohydrate and fat," said Peter Horvath, Ph.D., an associate professor of exercise and nutrition sciences at the University at Buffalo. During longer (one- to four-hour) workouts, 40 to 50 percent of your energy comes from fat. Translation: If you don't get enough of the nutrient, you'll run out of gas sooner. In fact, female athletes on a low-fat diet tired out 20 percent earlier during a race than those on a moderate-fat plan, according to a study in Medicine and Science in Sports and Exercise.
Making friends with fat can do more than help you reach the finish line -- it can also keep you off of the sidelines. When University at Buffalo researchers tracked female runners logging more than 20 miles a week, they found those who restricted their fat intake were more likely to suffer an injury than those who didn't. That's because the nutrient may help deliver vitamins important for tissue repair, support menstruation (which safeguards bones) and fight the fatigue that can literally trip you up. What's more, fat has been shown to reverse the immune-suppressing effects of a grueling training regimen, which, say experts, can fight off colds and flu.
Get the right amount
If you're going hard, you'll want to take in about 30 percent of your calories from fat. For a 2,000-calorie diet, that's about 67 grams per day. Some experts advocate going as high as 42 percent. On the flip side, dipping south of 15 percent will take a toll on your performance. Are your workouts less intense (walking) or lengthy (sprinting)? Set your target at 20 to 25 percent of calories.
Keep in mind that it takes your body longer to digest a handful of nuts than the same amount of crackers. To avoid race-day digestion drama, scale back in the two days leading up to the event. Consider dropping your fat intake to 25 percent of calories while upping carbs to about 60 percent. You'll continue to burn fat like a well-oiled machine, Horvath said, but you'll also top off your glycogen (carbs stored in muscle) bank.
Strike a balance
This doesn't mean inhaling pizza and cheese fries will shave minutes off your personal best. The type of fat you eat is just as important as the amount. For heart health, aim for a 1:1:1 ratio of monounsaturated (olive oil, avocado), polyunsaturated (salmon, walnuts) and saturated (cheese, beef) fats. And when it comes to the polyunsaturated category, look to add more omega-3 fats from cold-water fish, canola oil and flaxseed to further strengthen the immune system, Horvath said.
Worried that eating fat will go straight to your gut? Relax. Although fat contains more calories (nine per gram, more than twice the amount of carbs and protein), it also keeps you fuller for longer. To stay at your racing weight, stick to your usual daily calorie tally -- and opt for fat from whole foods, like salmon, nuts and avocado, instead of packaged foods.