A 2007 study found that a diet rich in monounsaturated fats can help prevent weight gain.
By Leslie Goldman
From the Runner's World April 2009 issue (title linked above)
Dieter's Strategy: Eat low-fat foods.
Runner's Strategy: Eat the right fats.
Though the fat-free craze peaked in the '90s, many dieters still avoid oils, butter, nuts, and other fatty foods. Their logic: If you don't want your body to store fat, then don't eat fat. Many dieters also know that one gram of fat packs nine calories, while protein and carbohydrate both contain just four calories per gram. Dieters can stretch the same number of calories a lot farther if they eat mostly carbs and protein in place of fat.
But the notion that having fat in your diet isn't a bad thing is catching on again. "I think it's a pretty antiquated thought now that we need to eliminate fat to lose weight," says Jonny Bowden, Ph.D., author of The 150 Most Effective Ways to Boost Energy Naturally. In fact, studies have shown that eating moderate amounts of fat can actually help you lose weight. The key is to make sure you're eating the right kinds. Saturated and trans fats are unhealthy because they raise your levels of LDL (so-called "bad cholesterol"). Trans fats may also lower your HDL (or "good cholesterol") levels and increase your risk for heart disease—not to mention weight gain. But unsaturated fats (which include mono- and polyunsaturated) have important benefits. Here's why runners should include these fats in their diet.
1. Keep You Satisfied: Unsaturated fats promote satiety, reduce hunger, and minimally impact blood sugar. That's important because if your blood sugar dips too low, you may experience cravings, brain fog, overeating, and low energy, making it "fiendishly difficult to lose weight," says Bowden.
2. Protect Heart Health: Unlike trans-fats, monounsaturated fats found in vegetable oils (such as olive and canola) and avocados have the added power to help lower LDL and reduce your risk of heart disease.
3. Reduce Injury: Unsaturated fats can help stave off injuries, such as stress fractures. A 2008 study in the Journal of the International Society of Sports Nutrition found that female runners on low-fat diets are at increased risk of injury—and a sidelined runner can't burn as many calories.
4. Decrease Joint Pain: Bowden adds that omega-3 fatty acids—which are a type of polyunsaturated fat found in fish (particularly in salmon), walnuts, and ground flaxseed—possess anti-inflammatory properties that can help soothe knee, back, and joint aches and pains that plague many runners. Translation: You'll hurt less and run more.