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Ellen Glickman-Weiss, Ph.D., FACSM
Don't live in LA or Florida? Well, maybe your frigid part of the country isn't so bad after all! Learn how colder temperatures may mean increased metabolism. [And for all you fat loss zealots - this article is NOT a recommendation to run around half-naked in cold air or water!]
During cold exposure the body attempts to maintain core temperature by generating heat, in part through shivering. During exposure to the cold the increase in shivering translates to an increase in metabolic rate that can account for a great amount of additional energy expended. For example, as indicated in Table 1 below, in the absence of cold stress, energy expenditure is approximately 2500 kcal for the average active male [of which resting metabolic rate (RMR) accounts for 1750 kcal, the thermic effect of food accounts for 250 kcal, and exercise energy expenditure is approximately 500 kcal]. It is fairly well understood that during exposure to the cold, shivering can cause up to a 2.5 times increase in metabolic rate in an effort to maintain core temperature. Therefore, if we assume that an individual is at rest and continuously cold stressed (shivering), the overall energy expenditure will increase to be approximately 5125 kcal over a 24-hour period of time! The increase in seen by multiplying RMR x 2.5 or,1750 x 2.5 = 4375 kcal and this value is then subtracted from actual RMR to arrive at the net increase above RMR (or 4375 – 1750 = 2625 kcal); This is the amount of energy expended or generating through shivering thermogenesis to maintain core temperature. Thus, the additional calories expended or used during cold exposure are much greater (2625 kcal greater than the thermoneutral conditions) and therefore the energy requirement or food intake should also be adjusted accordingly (to maintain body weight).
"It is fairly well understood that during exposure to the cold, shivering can cause up to a 2.5 times increase in metabolic rate in an effort to maintain core temperature."
The next obvious question is to optimize ones ability to sustain exposure to the cold, what type of energy requirement should be ingested, or, simply stated what should one eat? On the other hand, if weight loss is the desired option what should be done since it appears that energy expenditure is much greater during rest when one is cold stressed. To answer the first question we have to note that during shivering, many muscle groups are actually recruited and are being utilized at low intensities, this causes an increase in demand for fuel or energy demand to support the muscular activity. Therefore, it is not surprising that metabolic rate increases appreciably during cold exposure. Overall, in resting individuals exposed to either cold air or cold water, carbohydrates and fat contribute approximately equally to this increase in energy expenditure. Therefore a balanced diet is probably the best option as always.
Is cold exposure a possible method of weight loss? It is true that exposure to cold appears to increase energy expenditure considerably; however, is this the best plan? To arrive at the answer to this question, we can begin by explaining how one may expend these additional calories. If sitting semi-nude (swim suit only, no gloves, socks or hat !) in 42°F air with a considerable wind chill appeals to you perhaps this may be an option. However, most people get rather distressed when their fingers and toes get numb and cannot sustain extreme cold conditions for greater than 2-3 hours in this semi-nude state. Therefore, there are more effective ways to lose weight. The option of increasing calories expenditure (exercise) and reducing caloric intake appears not only to be the most healthy (stimulating the cardiovascular system and imposing the needed stress on skeletal muscle as well as bone) but the most effective in reducing ones body fat and maintaining or increasing one muscle mass. These benefits cannot be derived sitting in cold air or cold water.
Finally, what about if one exercises in the cold? Since we have established that exercise is the best way to expend calories, and we expend more calories in the cold, is it than better to exercise in the cold ?
Caloric expenditure is increased during light exercise in the cold, compared with the same exercise performed in a comfortable environment. The additional calories appear to be attributed to the increase in the metabolic demand brought about through shivering. Also, it has been shown (Jacobs et al., EJAP 54: 35-39, 1985) that critically low glycogen concentrations (carb stores) are probably reached more rapidly in an exercising muscle if the individual is being cooled during exercise or has been shivering or cooled before the exercise session. Low intensity exercise in the cold has a higher caloric expenditure than the same exercise in a warmer condition, but a balanced diet will be sufficient to account for this extra energy expenditure (again, if one wishes to maintain body size).
There are, of course are a number of factors that determine the extent to which an individual increases overall metabolic rate when exposed to the cold. These factors include: training status, gender, hormonal status, body composition (the amount of muscle or fat), stature (height, which affects the amount of surface exposed to the cold), diet, age, state of acclimation (use to the environmental conditions), clothing, cold stressor (air vs. water) as well as duration of cold exposure. Therefore, when attempting to make conclusions between studies, the magnitude of a given response is dependent upon the aforementioned factors.
EDITORS' NOTE: Dr. Glickman-Weiss researches thermogenic agents for the military and for industry. She is currently working on a promising botanical thermogenic formula which has recently hit the market and is sold by Bodyonics Pinnacle under the trade name, Adrenerlin. Read more about it upcoming issues of Virtual Muscle.
http://www.virtualmuscle.com/cold and fat loss.htm
Don't live in LA or Florida? Well, maybe your frigid part of the country isn't so bad after all! Learn how colder temperatures may mean increased metabolism. [And for all you fat loss zealots - this article is NOT a recommendation to run around half-naked in cold air or water!]
During cold exposure the body attempts to maintain core temperature by generating heat, in part through shivering. During exposure to the cold the increase in shivering translates to an increase in metabolic rate that can account for a great amount of additional energy expended. For example, as indicated in Table 1 below, in the absence of cold stress, energy expenditure is approximately 2500 kcal for the average active male [of which resting metabolic rate (RMR) accounts for 1750 kcal, the thermic effect of food accounts for 250 kcal, and exercise energy expenditure is approximately 500 kcal]. It is fairly well understood that during exposure to the cold, shivering can cause up to a 2.5 times increase in metabolic rate in an effort to maintain core temperature. Therefore, if we assume that an individual is at rest and continuously cold stressed (shivering), the overall energy expenditure will increase to be approximately 5125 kcal over a 24-hour period of time! The increase in seen by multiplying RMR x 2.5 or,1750 x 2.5 = 4375 kcal and this value is then subtracted from actual RMR to arrive at the net increase above RMR (or 4375 – 1750 = 2625 kcal); This is the amount of energy expended or generating through shivering thermogenesis to maintain core temperature. Thus, the additional calories expended or used during cold exposure are much greater (2625 kcal greater than the thermoneutral conditions) and therefore the energy requirement or food intake should also be adjusted accordingly (to maintain body weight).
"It is fairly well understood that during exposure to the cold, shivering can cause up to a 2.5 times increase in metabolic rate in an effort to maintain core temperature."
The next obvious question is to optimize ones ability to sustain exposure to the cold, what type of energy requirement should be ingested, or, simply stated what should one eat? On the other hand, if weight loss is the desired option what should be done since it appears that energy expenditure is much greater during rest when one is cold stressed. To answer the first question we have to note that during shivering, many muscle groups are actually recruited and are being utilized at low intensities, this causes an increase in demand for fuel or energy demand to support the muscular activity. Therefore, it is not surprising that metabolic rate increases appreciably during cold exposure. Overall, in resting individuals exposed to either cold air or cold water, carbohydrates and fat contribute approximately equally to this increase in energy expenditure. Therefore a balanced diet is probably the best option as always.
Is cold exposure a possible method of weight loss? It is true that exposure to cold appears to increase energy expenditure considerably; however, is this the best plan? To arrive at the answer to this question, we can begin by explaining how one may expend these additional calories. If sitting semi-nude (swim suit only, no gloves, socks or hat !) in 42°F air with a considerable wind chill appeals to you perhaps this may be an option. However, most people get rather distressed when their fingers and toes get numb and cannot sustain extreme cold conditions for greater than 2-3 hours in this semi-nude state. Therefore, there are more effective ways to lose weight. The option of increasing calories expenditure (exercise) and reducing caloric intake appears not only to be the most healthy (stimulating the cardiovascular system and imposing the needed stress on skeletal muscle as well as bone) but the most effective in reducing ones body fat and maintaining or increasing one muscle mass. These benefits cannot be derived sitting in cold air or cold water.
Finally, what about if one exercises in the cold? Since we have established that exercise is the best way to expend calories, and we expend more calories in the cold, is it than better to exercise in the cold ?
Caloric expenditure is increased during light exercise in the cold, compared with the same exercise performed in a comfortable environment. The additional calories appear to be attributed to the increase in the metabolic demand brought about through shivering. Also, it has been shown (Jacobs et al., EJAP 54: 35-39, 1985) that critically low glycogen concentrations (carb stores) are probably reached more rapidly in an exercising muscle if the individual is being cooled during exercise or has been shivering or cooled before the exercise session. Low intensity exercise in the cold has a higher caloric expenditure than the same exercise in a warmer condition, but a balanced diet will be sufficient to account for this extra energy expenditure (again, if one wishes to maintain body size).
There are, of course are a number of factors that determine the extent to which an individual increases overall metabolic rate when exposed to the cold. These factors include: training status, gender, hormonal status, body composition (the amount of muscle or fat), stature (height, which affects the amount of surface exposed to the cold), diet, age, state of acclimation (use to the environmental conditions), clothing, cold stressor (air vs. water) as well as duration of cold exposure. Therefore, when attempting to make conclusions between studies, the magnitude of a given response is dependent upon the aforementioned factors.
EDITORS' NOTE: Dr. Glickman-Weiss researches thermogenic agents for the military and for industry. She is currently working on a promising botanical thermogenic formula which has recently hit the market and is sold by Bodyonics Pinnacle under the trade name, Adrenerlin. Read more about it upcoming issues of Virtual Muscle.
http://www.virtualmuscle.com/cold and fat loss.htm
) , de hometrainer en het roeiapparaat om verveling te voorkomen. 
dat je een laag tempo moet nemen.. nee interval is het je-van-het! Je kunt veel intensiever gaan dan met voluit gaan over de hele tijd genomen en verbrandt nog zeer veel calorieën extra in de rusttijd tijdens en na de oefening..
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