Is "BMR" accurate on a carnivore diet?

#1

Hello.

I am new to this forum, but certainly not new to keto or carnivore dieting.

I have a theory and at the same time a question.

I have, for a long time, theorized that when you don’t eat vegetables you don’t use parts of the colon to digest foods.
Now this in turn has me wondering, does the " BMR" really hold water on this diet?

BMR ( BasalMetabolicRate ) is predicated on the body using a certain amount of calories during a day to keep the processes going - but if you are using less “processes” wouldn’t you use less calories?

Hoping for great discussions and answers

Alex

(Robert C) #2

“Selective colon surface area usage to drive down BRM theory” ???

This is not in the “Show me the science category” but, I think you should try to back this up by something (anything) from somewhere.

This post should certainly not be read as even potentially correct without some support - I have never heard of anything like this.

(bulkbiker) #3

But wouldn’t the BMR be elevated by requiring the body to make energy from only fat and protein as everyone tells us that glucose is easiest to digest and use as fuel… so maybe the body would need to work harder? Otherwise wouldn’t all the carnivores get fat due to a slowing BMR?

(Robert C) #4

Keto is fat and protein also - again, never heard this argument specifically against vegetables.
The inverse would be true too wouldn’t it? Vegans could claim parts of their colon don’t have to handle meat - so lower BMR?

I think BMR is somewhat demand driven.
A growing child (demand is growth) will (I think) have a higher BMR.
A laying still heavy thinker (physics major needing more glucose for the brain) will need more glucose to be generated in the liver than than a relaxed laying still dormant brained individual who’s biggest concern is what toppings they want on their pizza.

The reason I jumped on this post is that I want to avoid reading an unsupported post in a month or two:

blah blah blah blah blah and since we know Carnivore reduces BMR blah blah blah.

Even now, coming to the aid of this theory - feels like “Carnivore cannot be wrong” - even with an argument that would support vegans just as welll.

(mole person) #5

This has an element of truth. It’s not that parts of your colon no longer digest, but that less digestion happens in the lower colon when you don’t eat foods with fibre.

The rest of this doesn’t quite hold water. First of all the base metabolic rate is measured at the individual’s level. Thus it will already be affected by hormones, which in turn are affected by the types of food that you eat. So basically, calories used by the individual’s body processes are all part of the calculus.

Secondly, if anything, the carnivore is actually likely to use more calories rather than less calories in food processing. This may be one reason why the carnivore diet is so good for weight loss even when it’s not ketogenic. There are a lot of inefficiencies in the metabolism of protein. There is the deanimation process as well as the urea cycle which both use significant energy. Fibre, on the other hand, generally transports significant sugars with it into the colon where it is the gut bacteria that end up getting a large portion of the calories.

Finally, I doubt that very much in the way of calorie expenditure happens in the colon. Most of the digestion processes of the lower intestine are performed by gut bacteria and not by your own metabolism.

(bulkbiker) #6

Oh I agree I’m not claiming that it is correct just an interesting proposition. I must admit I’ve have never heard of it either.
As so far as I know BMR is extremely hard to measure? then we’re probably never going to find out either.

(Robert C) #7

I agree - not just hard to measure but, really one of those things that changes when you try to measure it (I think).

A person walks, talks, thinks, maybe exercises etc. many things throughout each day.

Lay them down with nothing to do one day (a completely novel situation for them) and measure their BMR??? Those stimuli don’t add up to something that affects their BMR every day?

Why would that laying down BMR have anything to do with their underlying BMR on normal days?

(bulkbiker) #8

Couldn’t agree more… well said.
The more I read and find out the less I think that there is anything in the human body that remains sttaic for any length of time. Blood sugar, cholesterol, BMR, hormones all go up and down throughout the day depending on many other variables that all have their own influence on all the others. How anyone can deduce from that that by eating 20 cals more or less a day over a year can have a significant impact on weight as I recently saw a dietitian say on twitter … the mind boggles at the complexity of it all.

(Elizabeth ) #9

Eating meat is thermogenic

(Robert C) #10

Yep - the way I think of these sorts of things (to reduce the complexity) is to always keep in mind, the body will adapt - both in the short term and the long term (my opinion).

Long term:
Eat 20 calories more or less per day and the body may slightly raise or lower body temperature (to keep what it thinks is the right amount of fat around - no more, no less).

Short term:
(Reused example coming - sorry) Eat a piece of pizza to break a 5 day fast vs. eating the same piece of pizza after many days of normal eating and having already just finished the rest of the pizza.

(I believe) Your body will take its time and extract all it can from that single piece of pizza at the end of a fast. But, your body will not try nearly as hard to get every last bit of the last piece of a large pizza in a non-fasted state (the more you stuff yourself, the more that goes through you less and less partially digested). In this case, I think people with BED would explode if their body treated every bit of food as if it was just finishing a long fast.

So, what I like to focus on is the DIRECTION of the adaptation to help determine overall effect. For some reason, it helps me organize my responses.

(You've tried everything else; why not try bacon?) #11

All sorts of variables are at play here. Firstly, there’s the thermic effect of food, or the energy cost of digesting. Protein digestion uses a fair amount of energy, but protein intake doesn’t really change when people go keto. I don’t believe there is that much difference between the thermic effects of carbohydrate and fat, so that’s pretty much a wash.

Resting metabolism (BMR) can go up when the body gets extra calories, since processes such as the uncoupling of mitochondria come into play (part of the origin of the “meat sweats”). Also, in the absence of insulin, there is more metabolic fuel available, because ingested calories are not being shunted to the adipose tissue.

The brain is a huge energy sink, and someone lying on the bed thinking (say, a programmer working on a knotty problem) is actually using more calories than you might . . . think. :grin:

Healthier mitochondria metabolize more. Well-developed muscles become more efficient and use less energy. But many people grow more muscle on keto—would that be enough to compensate for the increased efficiency?

Do ketones wasted in the breath or urine count towards the metabolic rate? They are literally “calories out,” after all! :grin:

My guess is that it’s imponderable. The only way to know for sure would be to take several thousand people, measure their BMR’s before and after they go carnivore, and see if there’s a difference.

(KCKO, KCFO 🥥) #12

All food travels the whole length of your digestive system, from your mouth opening to the [spoiler]asshole[/spoiler]. Some foods can pass through faster because they digest .

(The Algorist) #13

I know this is a year down the road but take a look at Dr. Paul Mason. His research says that we burn, on average, 271 kCal more per day when eating a carnivore or low carb diet. This stems from the bodies two types of fats: White fat and Brown fat. White fat stores energy (gets fatter) while brown fat burns energy. If you are thinking, “A fat that burns energy?!” I was right there with you! As you eat things that spike your insulin or cause you to become insulin resistant, your brown fat turns into white fat and you start storing more! As you eat fewer carbs or foods that cause insulin resistance (become more insulin sensitive), then your white fat turns into brown fat and you burn more!

tl;dr You burn around 270 kCal more per day if you eat a carnivore diet according to Dr. Paul Mason.

(Bob M) #14

I think a similar thing occurs with keto alone. No need to go carnivore.

#15

carnivore, more carnivore than the rest, omi and herbi, a true on carnivore gut length of colon is FAR shorter. Plant eaters, way different story on physical body situation. Simple true science. Rumimants and plant eating non ruminants like a horse or elephant that will not ingest meat have intestine lengths that are massively long and different in enzymes to process/digest/etc fiber and used and designed solely for fiber process and natural life.

think more about what is in the body vs. how it works against veg vs. meat in BMR which is mostly ‘calculated’ on flawed non carnivore eating studies or just something as so simple as a true carnivore mammal vs. an omi or herbi….all use energy and power so diff. and won’t ever be the same, each fit with organs to take what nature has intended for their survival and process it to its fullest for that mammal, each pulling true energy source from plant protein and meat protein sources each are ‘kinda intended’ to process as nature set them up…so…where are the studies of BMR on elephants vs. cows who are rumients but an elephant ain’t eating no steak protein so…ahhh, such a wide useless calculation truly BMR when you truly put it in a ‘very monster big picture’ of life…take it all with a grain of salt on that one and chatting it further would be stellar. I love this chat :slight_smile:

(Chris) #16

Yes BMR still holds water, but I would speculate you might be fishing in the right pond as to this idea of “parts not needing use so perhaps less energy is needed overall”. It’s a good question to ask, but there’s no studies on it that I’m aware of.

#17

yea well I agree that BMR holds water LOL and I hope I didn’t mean to come across solely as it won’t…but put apples to apples and not BMR on a species that will never act the same, live the same lifestyle, have any or most same medical issues or genetic issues and SO FRIGGIN’ diverse that one can then ‘just take that chance’ and lump it all under some calculation we all bow down to…and bow down we do…but to what do we bow? All here doing what is not the norm, pushing past ‘the expert’ nutrition and meanings/definitions and more are proving it all wrong as it is written, BMR falls right there for me :slight_smile: Is there calculations to burn a kcal in a dish, darn right there is…now show me the full studies and proof to fit all people and show me flawless studies and calculations to suit it all. no one can LOL and yet we bow. I say get past it and dump the obvious flawed everything out there and learn from basics of life and yes science of burning a kcal has merit and applying a lot of it to a physical body and more, but at some point, ya know, no 2 cellular beings will be the same, act the same, ever ever be clocked under so much useless ‘one size fits all’ cause we made it that way to fit all the science we can calculate…pfffft……not being combative to your post, me just playing off it :slight_smile:

#18

@The_Algorist Big WELCOME to you! I’ll have to check out Dr. Paul Mason’s website. Ty

(Windmill Tilter) #19

Yes, BMR still holds water regardless of your diet.

What may change however is that your metabolic rate will be higher on average during the day, but not for the reason that you think. Incidentally, carnivore is more likely to increase metabolic rate than decrease it. This change in metabolic rate has nothing to do with BMR however.

Metabolic rate is influenced by diet inducted thermogenisis. It takes calories to digest protein, fat, and carbs to varying degrees. It costs about 3% for fat, and 30% for protein. If you were substantially increase protein on a carnivore diet, which is likely, but by no means inevitable (the Paleo Ketogenic Diet is a prime example), your metabolic rate would in fact increase in proportion to the increase in protein.

If you increased your protein from 100g/day to 200g/day, this would be an increase in 100g of protein per day. That 100g protein contains 400kcals. Of that 400kcals, 30% of it would consumed in digestion, or 120kcals. That 120 kcals would directly impact your metabolic rate, and if you were to hook yourself up to a indirect calorimeter, it would reflect an temporary increase in your metabolic rate for the period of time that the digestion was occuring.

Put differently, any time you materially change your protein consumption, your metabolic rate will change accordingly, but this has nothing to do with BMR.