Protein Calories - The constant battle.

Updated: Aug 25, 2019

I was recently asked:

"Since fat loss is about energy balance and protein can be consumed for energy, at what point does the body start to primarily use protein as energy rather than cellular repair and function? As a follow on question, does long term protein over feeding lead to being "Protein adapted" in the same way you can be "FAT adapted". If I was very lean would that mean I would burn more muscle then fat?


Great question!


To answer, I'm going to speak in very broad terms and generalizations rather than my normal science geek speak to make it a little easier to understand and digest.


Every food you consume contains energy. This energy is contained within Carbon-Carbon bonds, that when broken down, release energy which your body can then use to generate ATP.

We will call this "Carbon Energy"

Single, double and Triple carbon bonds.

Both carbs and fat, are a way of storing carbon energy, with fats being a much denser option. This very broadly speaking is why Fat is equal to Carbs in terms of fat loss when calories are equal, because they are both just carbon bonds waiting to be used.


Every time you see a C-C bond, it means we can derive energy from it.

Protein is a little special. It too contains Carbon-Carbon bonds but they are locked up behind a number of nitrogen molecules which makes it difficult for your body to access.


It is actually these nitrogen molecules which give protein its high thermic affect of feeding of 18 - 25%. Litterally 1/4 of the energy stored in protein is used just trying to access it.



At the same time, your body prioritizes using protein for cellular repair and turn over rather than energy production. This means that a significant portion of your protein intake is never made available to the blood stream for energy production anyway.


Now technically no one knows exactly what the amount put aside for cellular function actually is, however we do know that muscle protein synthesis is maximally stimulated at 0.4gms/kg every 3-4 hours equating to about 1.6 - 2.4 grams/kg per day.


Muscle protein breakdown however continues to decline nearly linearly as protein intake increases.


This means there is no hard line where protein is used exclusively for energy. Rather there is a gradual increase in protein oxidation with intake that increases further once MPS is maximally stimulated.



If I were to draw an arbitrary line in the sand It seems reasonable to say that its about this level where further protein contributes mostly to energy production rather than cellular repair.

It is likely that under Strict caloric restriction or Protein Sparing Modified Fast (PSMF) conditions, any intake above 1.2-1.4 gms/lb will be used for energy production. We will assume 1.2gms/lb just know that this is an underestimate of an underestimate.


Of note, this very likely not a magical barrier you suddenly cross and everything past that is burnt for energy, nor is burning amino acids for energy a bad thing at all, apart from lean meat being expensive.


If we assume you are consuming 2.0gms/lb protein, (with 20grams Fat and 20 Grams Carbs), as under PSMF conditions, 0.8gms/lb of that should be available for energy production.


For the sake of the following maths, I will assume you are 200lbs at 10% BF.


LBM=180lbs Protein intake = 360gms/day Protein used for metabolic function = 216gms Protein available for energy production = 134gms = 518 calories. Minus 25% TEF = 384 net calories.


Under PSMF conditions, consuming over 360 grams of protein, may only net you as little as 384 calories of usable energy.


You can start to see why a PSMF works when you crunch the numbers.


But lets say you go crazy on whey protein and *somehow* manage to get into a caloric surplus in a PSMF. Would you get fat?


Yes, but alot less than you might think.


Protein and Carbs (and technically alcohol) almost NEVER contribute directly to fat gain. Whilst the metabolic pathways exists to turn them into fat, they very rarely contribute meaningfully to fat gain except under extreme over eating over several days. Instead they merely offset your body from burning fat for energy by providing an alternate energy substrate. Said differently, protein and Carbs indirectly contribute to fat gain by ensuring you store the dietary fat you eat (more technically they block fat oxidation), and even then only if you are in a calorie surplus.


So you gorged on whey, but you were a good ketogenic bodybuilder and kept your fats at 20 grams, what happens?


Well, your body will store that 20 grams of fat, burn what it needs for energy from protein then wee the rest out as urea.


It literally does not matter how much protein you over ate, you will only store the 20 grams of fat you ate. (Again, technically untrue, but the amount of fat generated by denovolipogenisis is SOOOO minuscule were really just being nit picky at this point.)


Now, I'm hopefully going to REALLY blow your noodle.


What do you think would happen if you were to fast for say 16 hours then over eat protein, some how getting into a calorie surplus for 8 hours?


Well, during the 16 hour fast you are in a negative calorie balance, burning stored body fat for energy. Now we know that even the slowest digesting protein takes about 8 hours to be fully absorbed, so lets assume for 8 of those 16 hours you're burning ZERO bodyfat (again, untrue but, lets roll with it), leaving another 8 hours where you are completely fasted. Assuming your an average male burning 2400 calories ever 24 hours, thats 800 calories of fat burnt during your fast or just under 90 gms of fat.


Then, during your feeding window, you over consume protein, consuming less than 20 grams fat. You store those twenty grams of fat, burn what ever protein your body needs for energy then wee out the rest.


Burn 90 grams of fat during the fast. Store 20 grams of fat during the feast.

The next day you repeat the process

Burn 90 grams of fat during the fast. Store 20 grams of fat during the feast.


and so on.....


This actually the basis of my recomp protocol, Beast Mode, which is currently still being drafted due to be released shortly.


Regarding can we become “Protein adapted" and would this lead to greater muscle catabolism if you were very lean, we don't really know for sure.


Though we do know that as we get leaner LBM losses increase substantially.


We also know that your body fat can only provide you approximately 69 calories/kg of total BF/Day. Study Here.


Assuming you need 3000 calories per day to support your body weight, and you have only 10kgs of fat on you.

69*10kg = 690 calories per day.


If you go below 2310 calories per day (3000-690) then the remaining deficit will have to be taken from elsewhere. Our Macro Calculator actually takes this into account and tells you your maximum daily deficit!


Initially this will be from liver and muscle glycogen, but there will come a time where your body will eventually have to catabolise muscle to provide the remaining energy deficit. (this doesn't account for adaptive thermogenisis, IE your metabolism slowing down)


The end state is never be in a prolonged deficit of more than 70 calories/kg of BF/day to avoid muscle loss.


Please note, that during a PSMF the deficit is routinely greater than this amount. This is why we conduct frequent refeeds. They restock things like glycogen stores which allow us to continue to be in a steep deficit with out relying on muscle proteins for energy production.

This doesnt mean that fat is neccersarily being burnt any faster, but it does ensure we are burning fat at the fastest rate humanly possible.


I hope that answers your question.


💖 Ella

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