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The research paper "The effects of fasting on core temperature ... in rats" explains that a discontinued calorie intake decreases the core body temperature of rats. Question is if an adequate intake of calories can contribute in preventing hypothermia and frostbites in humans?

For example, say that somebody in Alaska had to travel a small number of kilometers on snow-shoes, in a severe sub-zero temperature. Would one steady meal make any difference to her/his chances of avoiding frostbite and if so, would it matter what that meal consisted of?

A similar question can also asked about hypothermia.

Also, if there are contradictory findings between hypothermia and frostbite would a "sweet spot" exist?

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    What has your research revealed so far? – Carey Gregory Feb 28 at 15:45
  • Hello Constantin; I think that something that can make the question better is adding just one more source for what you have understood (based on the source). Questions with two sources are much more appreciated by the community than questions than just one, although just one is okay as well. – user8225 Mar 1 at 9:21
  • Thx. Will take it into consideration. – Constantthin Mar 1 at 9:25
  • I read on the net just know that the more calories a meal has, the greater the thermogenic affect it has on the body. So that needs to be added to the equation. – Constantthin Mar 6 at 9:39
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Summary

  • A single meal can decrease the risk of hypothermia during a few km travel in severe cold. Consequently, it could also decrease the risk of frostbite, but lack of studies prevents making any reliable conclusions.
  • Dietary protein generates more heat than carbohydrates and these more than fat.
  • Proper hydration can contribute to prevention of frostbite, because dehydration results in constriction of blood vessels in the skin.
  • In cold environments alcohol may lower body core temperature.

Macronutrients

After eating, some energy from food will be released as heat. This is known as diet-induced thermogenesis. The percent of calories that is converted to heat:

  • 15-30% from protein
  • 5-10% from carbohydrates
  • 1-3% from fat
  • ~10% from a mixed meal

According to Nutritional Needs in Cold and High-Altitude Environments: Applications for Military Personnel in Field Operations (National Academic Press, 1996):

  • Fat has the lowest thermogenic effect.
  • Carbohydrates have higher thermogenic effect, which can last for 2-3 hours and protein has even higher effect that can last 5-6 hours.

They also say:

A protein snack prior to retiring to sleep could provide some benefit from the thermic effect of protein in cold environments.

and:

The principal mechanism to reduce heat loss is the neurologically induced constriction of vessels in the skin and extremities. This response diminishes heat transfer from the body core to the surfaces. As a result, body surface temperatures fall rapidly upon exposure to cold (Veicsteinas et al., 1982). These low skin and extremity temperatures can result in cold injuries, especially to the hands and fingers.

..which means that hypothermia increases the risk of frostbite.

In one small 2002 study, they measured the effect of high-carbohydrate and high-protein meal on heat production:

Postprandial thermogenesis at 2.5 hours post-meal averaged about twofold higher on the high protein diet versus the high carbohydrate diet.

In another small 1999 study, they have found similar results:

A high protein and carbohydrate diet induces a greater thermic response in healthy individuals when compared to a high fat diet.

Water

Dehydration can cause constriction of blood vessels in the skin and can thus increase the risk of frostbite. According to one 1998 study, dehydration can reduce the blood flow through the skin in an exercising person by ~40%. So, proper hydration can contribute to prevention of frostbite.

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  • Which of your references supports your claim that a single meal can decrease the risk of frostbite? I can see where the diet-induced thermogenesis could delay hypothermia somewhat, but I'm skeptical it would help prevent frostbite. – Carey Gregory Mar 3 at 21:59
  • I added a quote (the second one) from that military guide, according to which hypothermia results in peripheral vasoconstriction and a drop of skin temperature, which increases the risk of cold injury. So, if food can help to prevent hypothermia, it also helps to prevent frostbite. Since the direct connection between meals and frostbite was not evaluated by studies, I removed the statement about frostbite, because I myself found it too promising. – Jan Mar 4 at 9:36

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