Why there is no one-size fits all "percentage of energy intake" for protein.

in #nutrition3 years ago

I haven't blogged about nutrition for a while. In fact, I have been turned off by nutrition on social media by the whole covid19, everyone is an expert, hive-mind, tribal thing that has been going on in 2020. It seems in 2020, almost everybody with a real clue on nutrition on social media has become part of one of a few tribes of covid19 fringe theory nutters. As a data nut, I've been looking at the covid19 data and listening to the claims made by the (mostly) anti-lockdown nutri-Twitter folks, and its embarrassing. Don't get me wrong, I don't like lockdown, definitely not a fan, but being against lockdown and making up shit the available data already refutes because you want other people to be against the same thing you are against, that isn't my cup of tea. In the nutrition space its been the reason for avoiding vegans. Where vegans will make claims about fiber and cholesterol and importantly low protein needs for humans, about climate change, environmental impact, and the mental health safety of a vegan diet, just to sway people to get onboard with their views on animal rights, so the anti-lockdown folks, often low-carb diet influencers, will do the same about any subject that could sway people to get onboard with their views on lock-downs. There is nothing wrong with being against lockdown just as there is nothing wrong with opposing cruelty to animals. The problem is, the Low Carb community has recently gone down the same cult-like path that vegans did before them.

But enough about why I turned away from nutrition on social media and on with the part about protein.

There are a lot of claims flying around regarding calories as a percentage of daily calories, how it should be in a specific universal range for everybody. In this blog I want to show that the ideal protein intake “as percentage of calorie intake” in fact depends on multiple personal factors, and that there is no one size fits all.

Let's start with calorie intake. Depending on your current goals, your energy intake should probably be somewhere between 80% and 105% of your daily energy expenditure (DEE). Between 80% and 95% if you are trying to lose body fat without losing (too much) muscle mass, and up to 105% if you are trying to gain muscle mass.

So we have our first variable, lets call it EP, denoting the percentage of your DEE that makes up your daily energy intake (DEI)

DEI = EP x DEE

Where EP is in the range 0.8 .. 1.05

Now what is your DEE. According to two important DEE fitting models, that we will get into next, your DEE is your Basic Metabolic Rate times your activity factor. This activity factor ranges from 1.2, when you are largely sedentary and get little to no exercise, up to about 1.9 if you are very active, work out regularly and have a job involving physical activity.

DEI = (EP x AF) x BMR

Where EP is in the range 0.8 .. 1.05 and AF is in the range 1.2 .. 1.9

We can combine the two factors EP and AF into a single factor, lets call it X1

DEI = X1 x BMR

Where X1 is in the range 1..2 (actually 0.96 .. 1.995 according to the math, but the numbers are not that accurate, soe 1..2 will do fine.

Now for BMR, as we mentioned, there are two alternative fits for BMR, both fit only against Lean Body Mass.

Cunningham: BMR = 22 x LBM + 500
Katch-Mcardle: BMR = 21.6 x LBM + 370

Again we can write this as factors with ranges:

BMR = X2 x LBM + X3

Where X2 is in the range 21.6 .. 22 and X3 in the range 370 .. 500

Together this makes:

DEI = X1 x X3 + X1 x X2 x LBM

If we fill out the ranges, we can define X4 and X5 and write it like this:

DEI = X4 + X5 x LBM

Where X4 is in the range 350 .. 1000 and X5 is in the range 21 .. 44
Remember 350 and 21 are for barely active people on a deficit while 1000 and 44 are for very active people trying to gain muscles mass.

Now we get to the other side of things. Protein. How much protein you should consume, like your BMR, very much depends on your lean body mass, If we assume you don’t want to lose lean body mass (what you shouldn’t want), then depending on personal factors, the low threshold for maintaining lean body mass is usually somewhere between 2.0 and 3.0 grams of protein. The higher levels will usually align with either weight loss goals or weight gain goals, with the lower values associated with maintenance mostly. Now, knowing a gram of protein equates about 4 calories, the intake of protein calories will ideally be:

DEIp = X6 x LBM

Where X6 is in the range 8 .. 12

So what does this mean for the percentage of energy you should try to get from protein?
Let’s look.

PP = 100 x DEIp / DEI = 100 x X6 x LBM / (X4 + X5 x LBM)

Lets look at the extremes:

PP1 = 800 x LBM / (1000 + 44 x LBM)
PP2 = 1200 x LBM /(350 + 21 x LBM)

Now let us fill in some extreme values for LBM, lets take a 40 kg woman with a mere 25 kg of lean body mass, and a muscular man with a whopping 80 kg of lean body mass. Now at one extreme, we have a very active woman with very little LBM to start with trying to gain weight on a mild energy surplus working out every day. Her protein target could be a mere 10% of her energy intake.

On the other extreme, we have an injured power lifter who gained some fat after his injury. He isn’t very active as he is recovering, but he is trying to lose weight and thus is at a 20% energy deficit. His protein target could be as high as 50% of his energy intake.

I hope this little blog post has some value in all the confusion about protein. In short, don't sweat percentages. Figure out your lean body mass and make sure you get roughly 2.5 grams of protein per kg of lean body mass. Possibly e wee bit more if you are trying to gain or lose weight. You can up it a bit more if you like to, but there is no real need for that, but unless you have kidney disease, or you are both very lean and are trying to eat a very low-fat diet, there is no harm from eating more protein than the targets discussed in this blog. People claiming otherwise, like the covid nutters discussed at the start of this blog, will usually have an agenda, in this case a (vegan) animal rights agenda. Ignore them. If these claims make you nervous, I get it, but try to at least get those 2.5 grams in if you can.

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