A runner asks: What’s wrong with sugar?

If I don’t need to lose weight, is there some reason I shouldn’t be using sugar? I do watch what I eat to get the best nutrition because I am training to run a marathon. I have sugar in my coffee in the morning. I think it helps during long runs.

Lanie

Don’t stress about those few teaspoons of the sweet stuff in your java, say a couple of nutrition experts we consulted. As long as you’re eating a healthful, balanced diet, it’s not the worst thing you can do.

The body needs carbohydrates — which include fruit sugars, refined sugars or starches such as bread and pasta — as an energy source to fuel the muscles. When you eat carbohydrates, the body breaks them down into glucose, which is pulled out of the blood and used by our body cells for energy. Refined sugars, such as table sugar and corn syrup, found in energy bars and sports drinks, are processed and used by the body extremely quickly.

So they’re actually fine for exercise — as long as you’re not gulping down handfuls of M&Ms, says Suzanne Girard Eberle, a Portland, Ore.-based registered dietitian and author of “Endurance Sports Nutrition.” “That’s the preferred fuel that our muscles are asking for,” she says. And it explains why the sugar in your coffee gives your morning runs an extra kick.

It also explains why so many sports foods, such as energy gels and drinks, contain sugar. True, you can get the same boost from foods such as raisins, fruit or even a bagel, but although some of those foods have better nutritional value, they also can be difficult to digest, especially if you have to refuel during a long training session. Chomping on a dense hunk of bread might be a challenge logistically, and it could cause some stomach distress when you begin moving again.

Eberle cautions to use sports foods wisely. “I shouldn’t be grabbing [a protein bar] because there’s nothing in the house for breakfast,” she says. “We can make smarter choices.”

Nancy Clark, a registered dietitian based in West Newton, Mass., and author of “Nancy Clark’s Food Guide for Marathoners,” recommends eating 200 to 300 calories about an hour before a run. That could include foods containing sugar, such as yogurt, a latte or some animal crackers. “It should be whatever you can tolerate and tastes good, and doesn’t talk back,” she says. Sugar “is easily digested. It’s just not politically correct.”

Some people avoid eating sugar before exercising because they fear an eventual blood sugar crash, but both Clark and Eberle say that’s not likely to happen if you continue to take in about 200 to 300 calories per hour of exercise. Exercise increases insulin sensitivity, which makes it easier for the body to get glucose into the cells, thus helping regulate your blood sugar better. If you do feel lightheaded, eat a little more.

— Jeannine Stein