The Upside of Sugar
We've been over the evils of sugar, but it does have its benefits, especially if you're active. "Sugar has a bad connotation attached to it," says Sternlicht. "But in moderation, unrefined sugars are an important and vital part of your diet." Sugar that is needed for activity-such as weight training or a cardio workout-can be used as fuel, and the rest will be stored in the liver and muscles as glycogen for later use. Unfortunately, our storage space is limited, and anything left over turns to fat.
This balancing act is a result of science which shows that sugar boosts performance. According to John Ivy, Ph.D., professor in the department of kinesiology and health education at the University of Texas, Austin, "[Any kind of] carbs taken during exercise improves endurance performance, especially if an athlete is competing for a prolonged period of time during which stores would be depleted. In fact, there is even some indication that carbs also improve short-term performance of intense exercise as brief as 20 minutes."
Taken after a workout, sugar-combined with protein-expedites recovery while helping you pack on new muscle. We've already established that sugar boosts insulin levels, which are typically low after a workout. In turn, insulin propels amino acids-the building blocks of muscle that you get from protein-directly into your tired and hungry musculature. In this way, sugar acts as a transport system, efficiently feeding your muscles when they need it most. (This also works with creatine, which is why many commercial creatine products are mixed with a Kool-Aid type of powder and why experts recommend you mix plain creatine in a non-acidic fruit juice.)
Each person reacts individually to sugar, but regardless of one's metabolism, paying strict heed to the following rules will keep your training efforts on track.
Limit Refined Sugars
Lack in nutrients and fiber, refined sugars are calorically dense, meaning they have lots of calories with little bulk. As a result, they don't put a dent in your appetite, so you can quickly eat too many. Sternlicht says no more than 15 percent to 20 percent of total carbohydrates should come from refined sugars. That's about 250 calories' worth in a 2,500-calories-a-day diet.
Choose Unrefined Sugars
Unrefined sugars are found in fruits, some vegetables and other whole foods and should make up the bulk of the carbs you eat every day. Fruits and vegetables still have fiber, water and vitamins, so it's nearly impossible to eat too many of them. For example, the average man would have to eat about 50 oranges or 24 pounds of cabbage per day just to maintain his weight.
Use Sugar for Peak Performance
Despite its drawbacks, sugar is essential for tough workouts. "Not only do you need a source of sugar or other carbohydrate to restock glycogen stores necessary for enhanced athletic performance," says Sternlicht, "but carbohydrates are also needed to burn fat. With an inadequate amount of glucose in your system, you will be left feeling lethargic during workouts and unable to train effectively." High-glycemic foods such as Gatorade (78) or pretzels (83) are good choices for long hikes or runs.
Don't Overdo It
Just because you work out doesn't mean you can eat a bowl of Pepsi-over-Cap'n Crunch for breakfast every morning. Your body still has a limited storage capacity for glucose, and excess sugars will be stored as body fat. That means you should eat unrefined sugar sources such as fruits, vegetables and grains to trim down, while avoiding candy, soda and other processed foods.
Time It Right
A study in the American Journal of Physiology has shown that taking in sugar immediately before you exercise inhibits the fat-burning effects of cardio. If you run in the morning, do so before eating breakfast. If you work out in the afternoon, focus on foods that have a low glycemic index, and eat them at least two hours before hitting the pavement.
Take In Sugar After Training
In contrast, consuming sugar after a workout is vital for restocking muscle-glycogen stores. In fact, in the hour immediately after a workout, almost none of the sugar you eat will be used to form fat. This is where high-glycemic-index foods come into play. Since insulin is anabolic-it quickly shunts nutrients into your muscles, stopping muscle breakdown while hastening repair-a quick insulin spike right after a workout is desirable.