Winter and Nutrition: Fueling for Cold Weather Exercise
Winter and Nutrition: Fueling for Cold Weather Exercise
By Nancy Clark, M.S., R.D.
Some athletes embrace winter''s chill as a welcome change from exercising in summer''s heat. But others complain about hating cold weather. If that''s your stance, remember that exercising with proper nutrition (and layers of dry clothing) offers the opportunity to chase away the chills. After all, an aerobic workout can increase your metabolism by seven to 10 times above the resting level. This means, if you were to exercise hard for an hour and dissipate no heat, you could raise your body temperature from 98.6 degrees to 140 degrees Fahrenheit. (You''d cook yourself in the process!) In the summer, your body sweats heavily to dissipate this heat. But in the winter, the warmth helps you survive in a cold environment. Runners can enjoy a tropical environment in their running suit within minutes of starting exercise.
Because food provides the fuel needed to generate this heat, the right sports diet is particularly important for skiers, skaters, runners and other athletes who are exposed to extreme cold. The following addresses some common questions and concerns about winter and nutrition and offers tips to help you enjoy the season. For safety''s sake, winter athletes should always carry with them some source of fuel in case of an unexpected slip on the ice or other incident that leaves them static in a frigid environment. Winter campers, for example, commonly keep a supply of dried fruit, chocolate or cookies nearby for fuel if they wake up cold in the middle of the night. You should have an emergency snack such as an energy bar tucked in your pocket, just in case.
Why do I feel hungrier in the winter than in the summer?
A drop in body temperature stimulates the appetite and you experience hunger. Hence, if you become chilled during winter exercise (or when swimming, for that matter), you''ll likely find yourself searching for food. Eating "stokes the furnace" and generates heat, helping to keep your body warm. Food''s overall warming effect is known as thermogenesis (that is, "heat making"). Thirty to 60 minutes after you eat, your body generates about 10 percent more heat than when you have an empty stomach. This increased metabolism stems primarily from energy released during digestion. Hence, eating not only provides fuel but also increases heat production, warmth.
Do I burn more calories when I exercise in the cold?
Cold weather itself does not increase calorie needs. You don''t burn extra calories unless your body temperature drops and you start to shiver. Remember, the weather can actually be tropical inside your exercise outfit. Your body does use a considerable amount of energy to warm and humidify the air you breathe when you exercise in the cold. For example, if you were to burn 600 calories while cross-country skiing for an hour in zero-degree Fahrenheit weather, you may use about 23 percent of those calories to warm the inspired air. In summer, you would have dissipated this heat via sweat. In winter, you sweat less. If you are wearing heavy clothes, you will burn a few more calories to carry the extra weight of skis, boots, heavy parka and snowshoes. The Army allows 10 percent more calories for the heavily clad troops who exercise in the cold. The weight of extra clothing on, let''s say, winter runners is generally minimal.
Why do I find myself shivering when I get cold?
Shivering is involuntary muscle tensing that generates heat and offers a warming effect. When you first become slightly chilled (such as when watching a football game), you''ll find yourself doing an isometric type of muscle tensing that can increase your metabolic rate two to four times. As you get further chilled, you''ll find yourself hopping from foot to foot and jumping around. This is nature''s way to get you to generate heat and warm your body. If you become so cold that you start to shiver, these vigorous muscular contractions generate lots of heat - perhaps 400 calories per hour. Such intense shivering quickly depletes your muscle glycogen stores and drains your energy. This is when you''ll be glad you have some emergency food in your pocket!
What''s a big nutritional mistake made by winter athletes?
Failing to drink enough fluids is a major problem among winter athletes, such as hockey players, skiers, runners and winter hikers. Cold blunts the thirst mechanism; you''ll feel less thirsty despite significant sweat loss (if you overdress), to say nothing of respiratory fluid loss. That is, winter athletes need to consciously consume fluids to replace the water that gets lost via breathing. When you breath in cold dry air, your body warms and humidifies that air. As you exhale, you lose significant amounts of water. Some winter athletes purposefully skimp on fluids because urinating can be problematic, too much hassle to shed layers of clothing (ski suit, hockey gear, snow pants, etc.) Yet, dehydration hurts performance and is one cause of failed mountaineering adventures.
What''s best to eat to warm myself up?
Becoming chilled by the winter weather can easily happen if you:
• wear sweaty, wet clothing that drains body heat,
The best way to warm yourself up is to consume warm carbohydrates such as hot cocoa, mulled cider and steaming soup, as well as oatmeal, chili and pasta. The warm food, added to the thermogenic effect of eating, contributes to rapid recovery.
In comparison, cold foods and fluids chill your body. Research subjects who ate a big bowl of ice cream in five minutes experienced a drop in fingertip temperature of 2 degrees F in the first five minutes, 5 degrees in 15 minutes. In summer, this cooling effect is desirable, but in winter, hot foods are the better way to warm yourself. Bring out the thermos of soup!
Why do I gain weight in the winter?
Some people eat more because they are bored and less active. Instead of playing tennis, they eat mindlessly in front of the TV. For others, the change of seasons has a marked affect upon their mood, known as seasonal affective disorder, or SAD. Changes in brain chemicals increase carbohydrate cravings and the desire to eat more. Holiday temptations also contribute to weight gain. A study of 195 people indicates they gained on average 0.8 pounds in the six weeks between Thanksgiving and New Years. Overweight and obese people gained even more, with about 14 percent of the group gaining more than five pounds. The problem is, very few of the subjects lost those holiday pounds. Hence, yearly holiday weight gain becomes a major contributor to America ''s obesity problem...that''s eight pounds in ten years.
One weight management solution is to stay active in the winter. By investing in proper clothing, you''ll be able to stay warm from head to toe. You''ll benefit from not only being able to enjoy exercise but also from sunlight, a good way to battle winter depression (and attempts to cheer yourself up with food). Winter exercise is an asset for managing health, weight and the winter blues. The tricks are to dress right, fuel well, prevent dehydration - and you''ll stay warm!
Nancy Clark, M.S., R.D., counsels both casual exercisers and competitive athletes at her successful private practice in Healthworks, the premier fitness center in Chestnut Hill, MA (617-383-6100). Her best-selling Sports Nutrition Guidebook, Third Edition ($23) and her Food Guide for Marathoners: Tips for Everyday Champions ($20) are available via www.nancyclarkrd.com or by sending a check to Sports Nutrition Services, PO Box 650124 , W. Newton , MA 02465 .
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