Bioavailability and Calorie Planning

[David D]

A few years back I lost 5 lbs (not water weight) after just 4 or 5 days so decided to better count my calories.   I got to the point that I can predict weight loss or gain to within a quarter pound after 6 days, so thought I’d share as it might spark some conversation in the community here.

Using gear skeptics recommended 65% fat (169kcal/oz) vs the more traditional 35% fat (131kcal/oz), one could save 2 lbs on food weight for a 7 day food carry, which is nothing to sneeze at. But 65% fat just isn’t practical.

My food plan uses Gearskeptic’s format but I added nutritional info for all my own ingredients. I then estimate the average kcal/oz for the entire carry. Without relying too much on olive oil bumps or whole nuts, I can pretty easily hit 130cal/oz average with food I love to eat, with the right combo of proteins and salts.

Using a BMR calculator and a PAL  estimated from my past trips (1.7), I then estimate total calories I’ll need and then project weight loss expected (lbs = calorie deficit/3500) based on calories carried. On my 4 day trip last week, I predicted 0 oz weight gain/loss, and on return weighed identical to what I was when I left. Admittedly a bit of a fluke but my calculations usually get me to within a quarter pound for up to 6 days.

I looked into the topic of bioavailability last winter because not all calories may be taken up by the body.  The best study I found was from the Scientists in the ARS Food Components and Health Laboratory in Beltsville, Maryland who found calorie uptake was less than the label by:

• Whole Pistachios: 5 % less

• Whole Walnuts: 21 % less

• Whole Almonds: 32 % less

• Chopped nuts provided the next fewest compared to the label

• Nut butters were consistent with the fat calories on the label

I don’t rely too heavily on whole nuts though, eating maybe 40g a day. I get the food density up using nut butters, crushed nuts in bars, Quaker harvest crunch (with crushed almonds), even some coconut powder, and of course some olive oil but not enough to dominate the taste of a meal.

This tells me at least that I have no issues with bioavailability from the other ingredients. That or my PAL is an overestimate that accurately offsets any bioavailability effects.

That’s really what matters, watch your weight after sections and then adjust calorie intake accordingly.

Using gearskeptic’s sheet as the baseline, its not too hard to whip together a spreadsheet based meal plan that will let you know exact what you’re getting in your food and if you’ll gain or lose weight

[Bill Budney]

Yes, GearSkeptic’s format is terrific, but his focus on calories from carbs and fat is, as you say, imperfect. It makes more sense, nutritionally-speaking, to focus first on protein.

Looking at macronutrients, the ones we need in highest quantity every day are essential amino acids from protein. We need it for almost everything our body does, because most body functions depend on something made from protein. We need even more of it while backpacking; causing wear and tear on muscles. While our bodies store fat and carbohydrate, we cannot store protein (other than in our muscles, which we need to preserve).

Getting the required essential fatty acids (EFAs) is pretty easy. A tablespoon or two of (fresh, non-oxidized) Extra Virgin Olive Oil will do the trick, or just eat whatever you like and you will probably get most of them. The hardest EFAs to get are DHA and EPA. The best sources of those are marine, hence the recent focus on small fatty fish (trout and salmon! or canned fish) and fish oil. If you supplement fish oil, capsules keep better than plain oil; it is hard to keep the stuff fresh on the trail without refrigeration. Freshly caught fish are the best.

There are no essential carbohydrates. It’s just fuel.

Don’t forget collagen and glycine for connective tissue and longevity.

[David D]

My wife doesn’t like fish so I take a fish oil capsule daily, they keep very well.

Good tip.  Time to start packing one a day on trips

[Jerry Adams]

when you say “bioavailable” do you mean the calories that aren’t just passed out the other end as poop?

are simple carbs like sugar more easily digested so you absorb more of it?

or, if you eat a lot of food, will it overload your digestion system so less is absorbed and more passed out the other end?

if you eat small amounts all day then more will be absorbed?

I’ve been losing weight during a backpacking trip for the last few years.  maybe 193 pounds when I leave and 188 pounds when I get back – lose 5 pounds.

When I get back home I eat lots of food especially carbs, spread out through the day, and I’ll gain back those 5 pounds in a few weeks.

I normally take about a pound of food per day.  If I add a little more, like another 4 ounces, it doesn’t make any difference – I still lose 5 pounds over a trip.

I gradually added body weight over the years until I was over 200 pounds a few years ago and was fine with losing 5 pounds, but I would rather not go below 190 pounds.  Some people as they get older keep losing weight, and then they don’t have enough body fat to survive an illness.  Like my mom.

I watched the gear skeptic video about nutrition.  I over analyze things, but for some reason, have not bothered to over analyze this.  I try not to take any food that contains water because that’s added weight for no reason.  I try to take a lot of food with fiber, like whole grains or dried vegetables/fruits because my intestinal microorganisms like it, even though that “adds weight”.

[John S.]

Interesting, now we need better ways to carry nut butters. Or maybe PB powder is the way to go…it should have good bioavailability like butter? But, I notice that some powders have lowered fat levels.

https://backpackinglight.com/forums/topic/31955/

[David D]

Jerry, that’s the basic idea, that after a certain amount or percentage per time, the body can’t process it.  I’m no expert on it, but read these details:

• https://www.usda.gov/media/blog/2018/03/23/going-nuts-calories
• https://www.multivu.com/assets/57147/documents/AJCN-BAER-FULL-STUDY-original.pdf

Adding weight as you age is tricky because we lose muscle mass (heavy).  Its why adding correct proteins through the day is important.

John S., the nut butter tubes discussed in that thread are unreliable and messy, my preference for nut butters:

• https://ziploc.com/en/Products/Containers/Round/Containers-Twist-Loc-Small

8 oz containers are 25g, 16oz 39g.  They aren’t water tight if even modest pressure is applied on the sides but I’ve never had peanut butter leak from them.   I load them with crunchy PB and honey and use it for lunch wraps or in Ramen dinner recipes (I make a mean sesame peanut noodle dish)

These weigh a bit more (16oz size = 45g) but are water tight (so far but just found them this year) & stronger:

• https://www.walmart.ca/en/ip/rubbermaid-takealongs-473-ml-twist-seal-storage-container-3-pack/6000108188066

I found both at Walmart (Canada)

For liquids, Nalgene Wide-Mouth HDPE Water Bottles are even more reliable but heavier (8.5oz size = 38g), my go to for olive oil

[Jerry Adams]

I like the title “Discrepancy between the Atwater factor predicted and empirically
measured energy values of almonds in human diets”

a couple extractions from those articles

“David Baer and Janet Novotny looked at how many calories of almonds, walnuts, and pistachios are used by the human body. There are a lot of factors to consider, such as whether the nuts are raw, roasted, or ground, and how well they’re chewed.”

” In whole raw nuts, the fewest fat calories were taken in. Chopped nuts provided the next fewest compared to the label, and nut butters were consistent with the fat calories on the label.”

So, if you create nut butter in your mouth by completely chewing whole nuts, you’d get the bioavailability of nut butter

I think there are other factors, like what else you ate at the same time, or what else you’re doing, like if you’re exercising maybe you’ll absorb fewer calories

I don’t think this is as applicable to eating when backpacking as gaining, maintaining, or losing weight in general

[David D]

> So, if you create nut butter in your mouth by completely chewing whole nuts, you’d get the bioavailability of nut butter”

I’d say more liked chopped nuts, and in my original post I did write “Chopped nuts provided the next fewest compared to the label… Nut butters were consistent with the fat calories on the label”

 

[Jerry Adams]

Yeah

Interesting subject with lots of unanswered questions

[Terran Terran]

I do a blended salted pistachio butter using red palm oil for the vitamin E . Full of antioxidants ( carotenoids ), the oil doesn’t go rancid. A little date syrup for sweetener rounds it out.

I’m thinking of mixing a little chia with it to help it through the pipes.

[Sarah Kirkconnell]

I haven’t eaten a nut in 10 years unless my youngest is not with me (he has severe nut/peanut allergies so we don’t keep them in our house at all)….you quickly find other ways to bump calories. And to honestly not worry so much. Don’t over think it so much. Just eat what you like – and that your body likes you eating. Figure out your calories/fat/protein you work best on. But don’t overly focus on “what is the highest calories” because man…it can get weird really fast. Hiking with a child with severe food allergies gets one to think out of the box for food. He eats a lot of jerky.

And…losing weight on a trip isn’t that huge of a concern if it is 5 to 10 pounds. You’ll gain it back quickly enough.

[David D]

Over analyzing, guilty as charged!  Comes with being an engineer I guess

A positive side effect of it is it led to a group of dinners I call the “core 40”, some are adaptations of Sarah’s recipes.  I group by carb type: ramen, couscous, mashed, instant rice, instant polenta and capellini.  Capellini makes for great freezer bag meals, there should be more recipes out there.  Pasta primavera is my ultimate comfort meal, after peanut noodles.

I like the gear skeptic format as I can quickly cut and paste ingredients to what I enjoy, see the macro and then augment with nuts/bars/treats or subbing in TVP on really long carries as needed.

The tool also tracks the water required, sums it for the trip and links to another sheet that calculates how many ounces of fuel I’ll need for all the boils, based on which stove and pot I take.  This really helps keep fuel and food weight down.

It makes planning and meal prep much less effort and faster, allows a ton of variety without marco penalties, doesn’t drive me to eat crap, quite the opposite, and I have it dialed in so I can accurately predict weight loss and fuel needed based on the conditions.

It takes some prep creating the spreadsheets, but that’s what winters are for and once done they’re done for life.  Its also very quick to update a recipe by updating a cell or two and the macro auto updates.

Here’s an example

BTW sorry to hear about the nuts (for your son and you), a few friends have the same and its not easy.

[Jerry Adams]

If it’s true that much of your calories pass through unabsorbed, that would change all those calculations

Carbs are 4 cal/g, fat is 9 cal/g.  But if simple carbs eaten on a relatively empty stomach, spaced out over the day, maybe they are most completely absorbed.  Maybe fat is not absorbed as well so the 9 cal/g over states the weight advantage.

Maybe this is a non issue because if you’re lightweight backpacking you won’t over eat because it weighs too much.  Maybe non absorption mainly happens when you over eat and overwhelm the digestion system.

Maybe if you’re exercising strenuously, your digestive system is deprioritized so is doesn’t absorb calories as well.  Then, a strategy to minimize weight might be to not eat much during the day when you’re exercising and then do most of your eating when you stop for the day.

I find that I’m not as hungry when hiking.  I have to remember to eat sometimes.  Or else I think my blood sugar decreases and I can get very weak.  Same thing with water.

It must be possible to measure all this so it can be over analyzed :)

[Jerry Adams]

and now google news is feeding me articles about bio availability

https://scitechdaily.com/animal-vs-plant-protein-new-research-suggests-that-these-protein-sources-are-not-nutritionally-equivalent/?expand_article=1

They took blood samples and looked at amino acids in the blood to determine how much was absorbed by digestive system

52% of lean pork protein is absorbed

43% eggs

40% black beans

31% almonds

I’m not sure I interpreted that correctly.  This is just one study…

I’m surprised how few of the calories are absorbed.

That makes more sense that animal protein is absorbed better than plant protein.

I usually take some beef jerky – maybe 1 ounce per day which is equivalent to 4 ounces of un-dehydrated beef.  And I eat 1.5 ounces of dehydrated beans. So, I probably get more available calories from the 1 ounce of jerky.

[Matthew / BPL]

if simple carbs eaten on a relatively empty stomach, spaced out over the day, maybe they are most completely absorbed.

Unscientific and without quantifiable evidence but I feel great hiking when I am drinking Perpeteum. I wonder if it has higher bioavailability due to the fact that it doesn’t have to be chewed? I’m ingesting those carbs (plus a little bit of fat and protein) in small doses as I work through a bottle.

[David D]

I’ve read studies that protein absorption is improved by spreading it out and taking it closer to the time of the intense activity so its better to snack more often and eat smaller dinners.   I think there’s something to binge eating leading to less uptake.

But even if some of your calories pass through unabsorbed, it doesn’t change these calculations as long as they accurately predict weight gain and loss.  It takes time to dial in predicting this with accuracy, but I just see it as another of those ultralight skills that replace carrying extra junk.

[Bill Budney]

If you intend to invoke muscle protein synthesis, then it is necessary to eat “meals” with 30-50g of protein at a time. Maybe 25, although there is no easy way to know whether or not you have started a muscle protein synthesis cycle. The thing that initiates a muscle-building cycle is a sufficient dose of leucine, but you need the rest of the amino acids so there is no point in focusing on leucine alone.

Muscles build slowly; over years or decades. Muscle loss happens quickly (and happens automatically with aging, as you mentioned above). One strategy for extending healthspan is to grow muscle while we can, in order to offset the loss as we age.

People over 65 need more protein than younger folks, although they often tend to eat less.

Of course, there are many other reasons that we need protein other than muscle protein synthesis, so total amount consumed in a day also matters, as you say.

For context, 25g of protein is approximately one hamburger. An 8oz steak has about 50g. A typical whey protein shake is 25-30g (or 50g for a “double”). Four eggs have about 28g (similar for two eggs plus two strips of bacon or two sausages).

 

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