Quote:
JAK...

According to one book I read on the energy costs of staying warm:

It takes 70kcal/hr just to keep the body alive; and
It takes 45kcal/hr to compensate for the heat lost by breathing in zero degree (F) air.

Carbohydrates burn the quickest, fats give the highest number of calories and last a long time, and proteins are the most EFFICIENT source of calories, but they are slow. I think not only do you need to increase your calories during winter, but you also need to base the fuel source you consume to the activity at hand. For stoking the fire at bedtime, a snack heavy in protein and fat, with a scosh of carb, will help keep you warm at night. In the morning you need to go heavy on the carbs and lighter on the fat and protein... you don't want to spend extra energy digesting a heavy meal. Lunch should be a combination of all three, heavier on the carbs again, but enough fat and protein to get you through the afternoon. Dinner could be heavier on the fat and protein, but give yourself time to digest before turning in. And don't forget to drink!!!!!

MNS
Thanks Midnight.
I think you are right on about more fats and proteins at bedtime. As I said the extra pound of food in winter is 50/50 carbs/fats, which works out to an extra 3000 calories per day, which is plenty for me. That is on top of my usual 2 pounds/day for Spring/Fall, which is mostly carbs/protiens with minimal fat because I already have enough on my body. That 2 pounds is not much more than 3000 calories because it has fibre and stuff, and perhaps some moisture. On top of all that I can burn up to a pound of body fat in a long day. Currently I have an extra 50 pounds or so. In Summer I will include as little as 20g of fat in my diet. In Spring/Fall I basically carry twice my summer starvation diet, which is still only 40g of fat, but I always carry at least 500g of honey and 500g of vegetable oil on top of everything else just in case. In winter even though I have fat to burn I find for some reason it takes a combination of dietary carbs and fat to really kick start the bodies furnace to burn its own fat. It also helps to warm the body up now and then to keep the furnace burning. If my hands and feet are cold I know the furnace isn't working as it should. Sometimes putting on a thicker hat and gloves is enough, but sometimes stopping for a meal is the answer.

I am not in great shape right now, and I am getting older, but I have always had a pretty good metabolism for cold weather and cold water, perhaps a little of nature and nurture. Also I have a fairly big engine cardiovascular wise, built more for endurance than speed, but when I am 230 pounds I think I am actually capable of burning fewer maximum calories per day versus when I am 170 pounds. I have done long days in cold weather, but I doubt I would need more than 6000 calories of dietary, even if I did manage to burn 9000 calories. If I was in top cross country skiing shape, perhaps at 165 pounds, I probably would require the 9000 calories for long winter days and nights.


This is more or less what I am striving for, based on 8-12 hours of travel per day, and based on a fairly large frame of perhaps 150 pounds lean body weight, mostly in the legs, but typically carrying about 20-60 pounds of excess fat on top of what would be a healthy minimum weight for endurance sports of perhaps 165 pounds.

Summer Hikes for Weight Loss,
12 hours travel but at long slow activity level max 400 kcal/hour:
Minimum (not counting emergency food):
Protien: 100g ~ 400kcal
Fast Carbs: 200g ~ 800kcal
Slow Carbs: 200g ~ 800kcal
Dietary Fat: 22g ~ 200kcal
Body Fat: 330g ~ 3000kcal
=========================
Food = 2200 kcal (mostly carbs)
Total = 5200 kcal (mostly fat, due to long slow activity)

Spring/Fall Hikes with more moderate weight Loss,
8-10 hours travel including some higher activity levels:
Minimum (not counting emergency food):
Protien: 125g ~ 500kcal
Fast Carbs: 400g ~ 1600kcal
Slow Carbs: 400g ~ 1600kcal
Dietary Fat: 44g ~ 400kcal
Body Fat: 165g ~ 1500kcal
=========================
Food = 4100 kcal (mostly carbs)
Total = 5600 kcal (fat and carbs, due to more mixed activities)

Winter long Slow Trudge Hikes plus night skiing from base camp.
12 hours travel with a mix of activity levels, weather permitting.
Minimum (not counting emergency food):
Protien: 150g ~ 500kcal
Fast Carbs: 500g ~ 2000kcal
Slow Carbs: 500g ~ 2000kcal
Dietary Fat:165g ~ 1500kcal
Body Fat: 165g ~ 1500kcal
=========================
Food = 6000 kcal (still mostly carbs, but a lot more fat)
Total = 7000 kcal (fat and carbs, more mixed activities)

The thing about winter however is the weather needs to be pretty good in order to have the confidence to really exhaust oneself. So I never set out to totally destroy myself in winter or even in Spring/Fall like I might in Summer. Also in Summer I can travel extremely light, which makes it easier to burn more fat over a longer period without destroying bones and joints. Of course even in Summer you could die of exposure in a cold rain if you exhaust yourself first, so you always need to be prepared to take shelter and eat. But in Winter, or even Spring/Fall, the weather can close in and you can have longer colder nights and stronger and colder Northerlies and so you really need to get some energy restored before a storm if you have exerted yourself before hand, which could take days if you have totally exhausted yourself, so you really can't do that, except on the last day perhaps. So I like to plan on long slow trudges or long slow skis mostly, but if the weather is clear and not too cold I will go for a fast ski by moonlight. I am not talking about alpine stuff, which I know nothing about. Similarly when I go paddling on the Bay of Fundy, even in late Summer, I never allow myself to be totally exhausted, because the water is so damned cold. When I want a really long hard paddle I will do that on the Saint John River. Similarly when sailing a small boat you can work pretty hard and long when it is blowing 20-25 knots and the water is not to cold, but once its blowing 30-35 knots you really need to pace yourself if the water is cold, and 30-35 knots just isn't safe at all up here in winter.

Of course no matter how much or how little you bring it always makes sense to have something like an extra 500g of honey and 500g of olive oil. 6500 kcal and pretty easy to pack and put back on the shelf when you get home.

p.s. Perhaps I need more protien for the long slow hikes rather than the short fast hikes. Not really sure. I think over 2-3 days it doesn't matter too much, but on longer hikes you would need to pay more attention to nutrients and protien and stuff like whether or not your body is actually able to rebuild itself as fast as you are tearing it down.