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The Athlete's Kitchen: Winter Nutrition--Fueling For Cold Weather Exercise
By Nancy Clark, MS, RD, CSSD
January/February 2012
If you are a winter runner, you want to pay careful attention to your sports diet. These tips can to help you fuel wisely for cold weather workouts.
Winter Hydration
• Cold blunts the thirst mechanism so you will feel less thirsty despite significant sweat loss and you may not “think to drink.”
• Winter runners (especially those at high altitude) need to consciously consume fluids to replace the water vapor that gets exhaled via breathing. When you breathe in cold dry air, your body warms and humidifies that air. As you exhale, you lose significant amounts of water. You can see this vapor (“steam”) when you breathe.
• Unless you are hot, you do not want to drink icy water. Cold water can cool you off and give you the chills. The better choice is to have an insulated water bottle or a bottle filled with hot sports drink--covered with a wool sock to help retain the heat.
• Dress in layers so you can remove a layer as you become warmer. Simply taking off a hat is cooling--30% to 40% of body heat gets lost through the head.
• Some winter athletes purposefully skimp on fluids to minimize the need to urinate. There's no doubt that undoing layer after layer of clothing (e.g., running or cross country ski outfit, etc.) can be a hassle but dehydration hurts performance. Whether you are running or skiing, you still need to drink.
Winter Fuel
You need adequate pre-run fuel to generate body heat, so fuel-up before you embark on a long winter run or do any outside activity in extreme cold.
• The overall warming effect of food is known as thermogenesis (that is, "heat making"). Thirty to sixty minutes after you eat, your body generates about 10% more heat than when you have an empty stomach. Hence, eating not only provides fuel but also increases heat production (warmth).
• Running can increase your metabolism by 7 to 10 times above the resting level. That means, if you were to run hard for an hour and dissipate no heat, you would 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. Running is an excellent way to warm up in the winter.
• If you become chilled during winter exercise you will likely find yourself searching for food. A drop in body temperature stimulates the appetite and you experience hunger. Your body wants fuel to "stoke the furnace" so it can generate heat.
• Here’s a safety tip: you should always carry some source of emergency food (e.g., energy bar) with you in case you slip on the ice or experience some incident that leaves you static in a frigid environment.
Energy Needs
Cold weather itself does not increase energy needs, but you will burn extra calories if your body temperature drops and you start to shiver. Shivering is involuntary muscle tensing that generates heat.
What happens when you get chilled?
1) When you first become slightly chilled (such as waiting for your running buddies to show up), you will find yourself doing an isometric type of muscle tensing that can increase your metabolic rate two to four times.
2) As you get further chilled, you will 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.
3) 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 emergency food with you.
Winter Recovery Foods
• To chase away chills, replenish depleted glycogen stores, rehydrate your body, and enjoy warm carbohydrates with a little protein, such as hot cocoa made with milk, oatmeal with nuts, lentil soup, chili, and pasta with meatballs. The warm food, added to the thermogenic effect of eating, contributes to rapid recovery.
• In comparison, eating cold foods and frozen fluids can chill your body. Save the slushie (ice slurry) for summer workouts; it will cool you off. In winter, you want warm foods to fuel your workouts. Bring out the mulled cider or thermos of soup.
Winter Weight Gain
Many runners bemoan winter weight gain. Some eat too much because they are bored and less active. Others experience seasonal affective disorder (SAD). The change of seasons has a marked effect upon their mood. Changes in brain chemicals increase carbohydrate cravings and the desire to eat more. The temptations of winter holiday foods can also contribute to weight gain.
• To limit winter weight gain, stay active and keep running. Exercise helps manage health, weight, and the winter blues. The tricks are to invest in proper clothing, fuel well, and prevent dehydration so you can stay warm and enjoy the outdoor winter wonderland.
Nancy Clark, MS RD offers nutrition consultations to casual exercisers and competitive athletes at her private practice located at Healthworks, the premier fitness center in Chestnut Hill MA (617-795-1875). Her popular Sports Nutrition Guidebook and food guides for runners, cyclists, and soccer players are available at www.nancyclarkrd.com. See also www.sportsnutritionworkshop.com.
Reference
1. Johnson C, A Davenport, M Hansen, D Bacharach. Pre-competition hydration status of high school athletes participating in different sports. Med Sci Sport Exerc 42(5): S128 (Abstract 1149).