When Fat Goes Bad
While you need some fat – especially healthy fats -- you don't need these two: Saturated fats and trans fats. "There is no amount of training that makes these good for you," says Jenna Bell, Ph.D., RD, nutrition consultant and cofounder of swimbikeruneat.com.
Saturated fats, found in meat and full-fat dairy products (think butter, cheesecake and ice cream) push up your risk of heart disease and stroke.
More: 5 Heart-Healthy Nutrients for Athletes
Trans fats—oils that are hydrogenated to increase the shelf life of the products they're in—are even worse (think packaged cookies, chips, and many margarines).
For every two percent of extra calories from trans fats that you eat daily, your risk of coronary heart disease goes up 23 percent.
Considering that heart disease is already the number one killer in America, that jump in risk is huge (and potentially deadly).
More: How You Can Lower Your Risk for Heart Disease
Although dietary guidelines recommend keeping saturated and trans fats to less than 10 percent of your calorie intake, "there's really no acceptable level," Kendig says.
How do you tell the difference between good and bad fats?
When it comes to getting healthy fats in your life, you can look at labels and figure out percentages, or you can follow Bell's easy, restaurant and farmer's market-friendly system:
"Look at fats in two ways. Ask yourself, 'is it plant or sea fat, or is it animal (or farm) fat?' Focus on plant and ocean fats and they will serve you well."
More: 3 Plant-Based Pre-Race Meals for Runners
Perfect your nutrition to boost your performance. Sign up for a race near you.