I’m so confused re: daily calorie requirements

[Curtis B.]

I've read perhaps 30 posts and a number of outside resources and confess to being very confused as I attempt to compute approximate daily calorie requirements.

I tend to either starve or gain weight during weekend or longer hikes. I'd like to find a middle ground.

My family is doing a 5-day, 75 mile hike in Yellowstone later this month. If I go to a number of calorie counting websites (ie caloriesperhour.com) I find that for a 10-hour day of hiking I should be consuming 8300 calories (age 43, 230lbs).

Yet here most people talk about having a caloric intake of ~3500/day. Are people assuming that the remainder are going to be provided by body fat? I certainly have plenty of weight to lose, but planning to lose 1 pound per day seems unsafe.

How do you reasonably accurately compute calorie requirements for men, women, and teen children?

[CW]

Those sites tell you what you might burn, on average. They don't tell you what to consume.

I wouldn't carry more than 2 lbs of food a day and at 125 cal/oz that'll get you 4000 cals. Most people either make up the rest in body fat or gorge in town before/after the trip. Some people even go so far as to put on fat prior to a trip (see Arctic 1000).

Up to about 5 days though, I doubt you'll notice any real weight loss from under eating on the trail. I usually weigh myself after a trip and the scale definitely shows a loss, but after a few days, my weight returns to normal. I chalk it up to water loss, etc.

[Jamie Shortt]

Curtis, I'm with Chris 2 lbs/food/day if it is 125 cal/oz will be plenty. I never eat more than 1.25 lbs/day traveling 20-25 miles. Granted I tend to take shorter trips because of work/family but I've never had issues. Like Chris I always weigh less afterwards 2-5 lbs, but within a few days it is usually back (to my disappointment).

Some additional thoughts…75 miles over 5 days is 15 miles per day (I'm sure you already knew that). At 10 hours hiking/day that is traveling at 1.5 miles/hour. This is a pretty slow pace even for trail hiking. I believe walking at this pace (1.5) on flat ground is only like 125 cal/hour. Even if you double it for trail hiking it goes to maybe 250/hour additional. A normal day is what 2000 calories. I get at most your at maybe 4500 cal/day. I'm not sure if adding is correct, but it would only overestimate. With 2 lbs/day you should be carrying 4000 cal/day. If you eat it all I doubt you will even loose weight over 5 days, maybe a lb.

One source I found says it takes 90 calories to walk 1 mile if you weigh 150 lbs. 90*15 = 1350. OK so lets double it for trail walking you get 2750 (wow close to 250 cal/hour like the above example). Now lets try looking at cal/hour and adding up

10 hours trail walking * 275 = 2750
8 hours sleeping * 65 = 520
6 hours camp craft * 125 = 750

total is 4020 calories

I know this is at odds with what many calculators estimate but it is consistent with my experience. Maybe going from 150 to 230 lbs make a bigger difference than I anticipate. Not sure. Also doubling the calorie rate from casual walking to backpacking might grossly underestimate the burn. As pack weight goes up certainly calories would as well. Another reason to lighten up…means you can carry less food.

Jamie

[David Adair]

Curtis- I just got back from a 5 day trip with my daughter in the Absaroka Wilderness just north of Yellowstone. Please permit me a couple of observations and suggestions:

There are a lot of folks on this website that can leisurely do 15 mile days in the mountains. After a week or two of hiking most people probably could. However, pounding ground all day every day is not everybody's idea of a good time. So unless you know everyone is in shape and prepared for those kind of miles in that particular terrain I would suggest keeping it to less than ten. Or less than seven if you have more than say 1500 feet vertical or 10,000 foot elevations. A short day in the middle will give everybody time to recoup, have a camp fire and relax. Teens will always find a way to entertain themselves exploring or hanging around camp. That is lovely country, you don't want to be too focused on making miles to enjoy it.

Personally, I don't have much appetite the first four days of a hike. (Must be living off my strategic reserves of stored pepperoni pizza and beer). I can lose 2 lbs a day without any hunger or stress. So IMO food requirements for short trips heavily depends on available reserves. People without reserves will need the full caloric input right away while others will wait a day or two. I think Mike C's article suggests 1.4 lbs pppd for short trips. I suspect this is enough and probably too much if every one is not already a skinny starving athlete.

BTW a one big hit on our hike was one package each per person of sliced Canadian Bacon and Ritz crackers. Keeps well and supplements protein deprived DH dinners.

Best wishes for your trip!

[backpackerchick]

Here are some very rough numbers to start with.

Dean Karnazes often throws out data that suggests that he consumes about 600 kcal/hr during his long endeavors. But he is not your average hiker!

Very roughly, a 70kg (154lbs) male burns about 100 kcals/mile while covering flat terrain on foot. (If you are bigger, naturally you burn more!) If you are overweight (carrying excess fat), I would probably work out a fudge factor based on an "ideal weight". This traditional number has been found to hold up pretty well regardless of your speed. Based on the timing fudge factors for elevation and the like presented in Freedom of the Hills and elsewhere, you can come up with a revised "mileage" to use. (Covering a mile up hill requires more energy than covering one on flat ground.)

1lb/454 g/lb x 9kcal/g fat = 4082kcal

Their are about 4000 "calories" in a lb of fat.

Also, remember that you have a baseline metabolic requirement — even if you sit on the couch all day — just to keep the organs going, etc. Often quoted as 1500 kcal/day for our 70kg male specimen.

Another thing, how many days of hiking does it take you to get your hiking appetite going. For many, it is several days.

(I am procrastinating!)

[Bob Gross]

Something that relates to daily calories is time.

Some backpackers really like to sit around camp and enjoy the view, and I understand that. You may have lots of time for cooking and eating.

On the other hand, some backpackers like to stay on the trail more, and they eat enough to maintain their energy, and that's all.

I saw a trail runner the other day, running along the JMT southbound near Muir Pass, so he was likely doing 50+ miles that day. He wore a backpack that was about the size of a coffee can, and that is all. He must have been getting water directly from streams. He had no time.

–B.G.–

[CW]

FWIW, there are 3500 cals in 1 lb of body fat, and not 4000 as the calculation would suggest.

[Sarah Kirkconnell]

Teens should nearly always have twice as much food as adults. Cuts back on the whining and them eating YOUR food.

That of course is YMMV. Ford eats a scary amount of food. He is 6 feet and weighs maybe 120 lbs. Must be nice. Last hike with him he ate all of HIS food, then ate all of mine. I was starving by the end. He will have had a massive dinner and then eat his toddler brothers stash of crackers O_0

Also, if anyone gets shaky from not eating you need to make sure they have more food.

[backpackerchick]

A gram of fat yields 9kcal energy. If you hunk off a chunk of human body fat with a knife, it is not pure fat but loose fibrous connective tissue packed with fat cells. These additional structures contained in human adipose tissue do not provide as efficient a store of energy as fat.

Just out of curiosity, how are you coming up with 3500 kcal/lb fat?

[CW]

I didn't come up with it. It's a pretty well known and accepted number amongst nutritionists.

[backpackerchick]

Human adipose tissue ("body fat") is only 80% fat; the remaining 20% is composed of connective tissue, cellular components and water. So yes, a lb human "body fat", which contains water and protein as well as fat, will yield less energy than lb of fat.

However, in calculating nutritional requirements, 1 gram fat yields 9 kcal of energy. I am not aware of any dispute here. As such, 1 lb fat contains slightly over 4000kcal energy.

[Bob Gross]

"Cuts back on the whining"

Yes, but not nearly enough. Whining is in their DNA.

(On Kilimanjaro, we got to 16,000 feet in a fog, and one 14-year-old girl started whining. Her mother took her aside, shook her finger at her, and told her "No whining. Act like an adult." About 36 hours later, the kid hit the summit.)

"Also, if anyone gets shaky from not eating you need to make sure they have more food."

Absolutely. In fact, I think that every backpacker should have their own secret snack stash. It must be something that they like, and that they can eat right before they get shaky or weak, and does not require cooking. It doesn't have to be a lot. In fact, a tiny snack will digest faster than a big snack. Maybe it is only a candy bar. Maybe it is two spoonsful of Gatorade. For me, it is dehydrated pear slices. I'll put a ziploc bag of those in my pocket and then hit into them when I still have an hour to go before my meal in camp.

–B.G.–

[Chris S]

I've always heard the 3500 figure as well. I just googled it and the first result explains the discrepancy.

http://www.caloriesperhour.com/tutorial_pound.php

[backpackerchick]

So once you differentiate between fat [9kcal/g] and "body fat" better called adipose tissue [approx 80% fat + connective tissue (protein and carbohydrate both of which yield 4 kcal/g)+water which of course yields no energy] sounds about right :)

[Anonymous]

"Just out of curiosity, how are you coming up with 3500 kcal/lb fat?"

Do a Google search with the argument "calories in body fat". 3500 calories is the number commonly used. The number you specified would be accurate for dietary fat.

[David Adair]

Yes, in theory there is no difference between theory and practice but in practice there is. I just don't see being referred to as Adipose A$$ any improvement.)

[Anonymous]

"So once you differentiate between fat [9kcal/g] and "body fat"

In your original post were you referring to dietary fat or body fat/adipose tissue?

I think that may be where the confusion begins.

[Anonymous]

"My family is doing a 5-day, 75 mile hike in Yellowstone later this month. If I go to a number of calorie counting websites (ie caloriesperhour.com) I find that for a 10-hour day of hiking I should be consuming 8300 calories (age 43, 230lbs)."

Curtis,

The average number of calories burned by a Tour de France rider is 5900, with a max of 9000. These guys are working waaaay harder than you will be on a 15 mile day. IIRC, Dr J and Co estimated they would burn up to 7000 calories/day during the Arctic 1000, but they were doing high mileage in challenging terrain. Again, IIRC, for the first week or so of the trip, they relied on body fat to provide a significant percentage of those calories and thus carried only 1.5# of food/day to supplement it, heavily weighted toward carbs to support the metabolism of body fat. If you have body fat to spare, you might want to check out the Arctic 1000 website write up on their food strategy. I suspect you could use the same approach they did during their first week on your 5 day trip and do just fine. Of one thing I am pretty certain: You won't need 8000 calories/day. I have been using that strategy for several years now on trips up to 10 days, and it has worked very well for me. I bulk up before a trip and lose the excess fat during the trip plus a pound or so occasionally, at a rate of ~1/2 pound of body fat/day, not enough to cause damage. My 2 cents.

[backpackerchick]

I use the word fat to refer to fat! It can be dietary fat or the content of an adipose cell — 1g of either yields 9 kcal of energy.

I am not going to underestimate Curtis's planned endeavor. I don't know what those miles involve. I don't know how much he is hauling. And he's a big guy at 100+ kg — more than twice my weight. However, generally speaking 8000 kcal/day is a VERY large energy requirement for a healthy person (even a big guy) especially in warm weather.

[Bob Gross]

"world fat"

I give up. What is world fat?

Is that like whirled peas?

–B.G.–

[Anonymous]

"I use the word fat to refer to fat! It can be dietary fat or the content of an adipose cell — 1g of either yields 9 kcal of energy"

Not exactly true, Hartley. I copied over an explanation from a Google search, "adipose cell calorie content" that explains in simple terms the difference between dietary fat and body fat, as follows:

"The content of an adipose cell is not entirely fat. Side Bar 1. How many Calories are Really in a Pound of Fat?
One pound of fat is 3, 500 calories. However, one gram of fat is equivalent to 9 calories. Therefore, multiplying 9 calories/gram x 454 grams = 4,086 calories. Why the difference? Fat stored in adipocytes (fat cells) contains minerals, water and small amounts of protein, reducing the caloric content of one pound of body fat to roughly 3,500".

That being said, the actual fat molecules stored in an adipocyte, mainly in the form of long chain triglycerides, do yield ~9 caloires/gram. Medium chain triglycerides found in coconut oil among other sources yield slightly less, about 8.3 calories/gram. Apparently not all fats are created equal. Funny world, eh?

[backpackerchick]

The composition of fatty tissue also varies depending on where it is found on the body — adipose tissue in boobs is not the same as fat stored on the liver. Fatty tissue in the liver has a higher actual fat content and as such would yield more than the rough 3500 kcal/lb. (Let's switch to SI units — much less confusing!)

DEXA scanning is probably the best way to readily estimate "body fat percentage". It would seem, based on the technology, that DEXA measures the actual fat content of the body as opposed to the quantity of adipose tissue. Any radiologists out there?

I like the idea that I am not the only procrastinator out here! Time to hit the trail or I suppose at this hour the road or pool. Cheers!

[Dean F.]

IIRC some of the caloric formulas for hiking were developed from military data. That's a different population than UL hikers and makes a poor model for us. I think that some also subsume your basal caloric requirement into the mileage, so if you're making good mileage the models give results heavily skewed to the high end. I can't IMAGINE eating >10,000 calories a day. Heck, even the "Vermont prison study" topped out at 8,000 calories.

[Derek Goffin]

It seems to me that counting the calories of a pound of adipose tissue stuffed with fat is the same as counting the calories in a packet of corn flakes when counting the calories of the corn flakes. Most people dont eat the cardboard and your body doesnt easily consume the adipose tissue container. Of course if you are carving off a pound of body fat or undergoing liposuction perhaps it matters but on this thread fat has 9 calories per gram or thereabouts and the rest is just confusion.

[Anonymous]

"It seems to me that counting the calories of a pound of adipose tissue stuffed with fat is the same as counting the calories in a packet of corn flakes when counting the calories of the corn flakes. Most people dont eat the cardboard and your body doesnt easily consume the adipose tissue container. Of course if you are carving off a pound of body fat or undergoing liposuction perhaps it matters but on this thread fat has 9 calories per gram or thereabouts and the rest is just confusion."

The end product has 9 calories, Derek. However, if you are using body fat as a purposeful component of your food planning, you will need to use the 3500 figure. That is how your body stores fat and that is what you will have to measure to plan you diet accurately. One pound of body fat will supply ~3500 calories of metabolizable fat at 9 calories/gram of fat supplied. Unlike the cardboard box that corn flakes comes in, which you can discard, you can't discard the structure that body fat is stored in to lighten up.

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