Whether you're an Olympic athlete or a weekend warrior, winter sports require that you pay special attention to food and water, cautions UC Davis nutritionist Liz Applegate, an expert on nutrition and fitness.

"Particularly for sports like snowshoeing or downhill and cross-country skiing, where you're out for several hours, you need to make sure that you take plenty of food with you," she says. "If your blood sugar gets low, you're more likely to become confused and run the risk of getting lost." Plus, running out of "fuel" results in poor performance and makes it hard to stay warm. She suggests tucking a half-cup of dried fruit and an energy bar -- about 200 calories -- into your pocket before taking off for a half-day in the snow and perhaps something extra in case of an emergency. For all cold-weather exercising,

Applegate stresses that a high-carbohydrate food, perhaps hot cereal and a banana, should be eaten a couple of hours before your workout. "You'll find that you exercise harder and longer, and actually burn more calories than if you started your workout on an empty stomach," she says. And even though it's cold, you need to make sure you're drinking plenty of water because cold air is drier than warm air and draws out more body moisture. She also urges winter athletes to dress in layers, rather than in one heavy coat, so that they can peel off one layer as they warm up without risking a sudden drop in body temperature.

Applegate is one of the nutritionists made available by the International Olympic Committee to advise Olympic athletes. A former award-winning triathlete, she is the author of several books including "Eat Smart, Play Hard."