Protein Requirement

The common figure is that the body needs around 0.8 g of protein per 1 kg of body weight per day. And there are voices that dispute this and put the number considerably higher. The usual reason given: 0.8 g is the order of magnitude that prevents deficiency symptoms, but does not guarantee an optimal supply. It is generally accepted that this is not a target to be reached if at all possible, but a minimum.

I have no intention of joining that argument. I am coming at it from a different direction:

What does the body need

Strictly speaking, the body does not need protein at all - it needs amino acids. Some of them are Essential nutrients are those that the body cannot synthesise itself and must obtain through food – vitamins, essential amino acids, and fatty acids. and some Nonessential nutrients are those that the body can synthesise itself out of other nutrients. Therefor these do not have to be provided with food..

And, as we know from other articles here, nutrients differ in how bioavailable they are. Which is to say: the body cannot take everything up simply because we have eaten it.

There is now a new simulator here for exactly this: for various compositions it shows how much protein (and how much food) different diets and food combinations need in order to meet the daily requirement for essential amino acids and total protein.

In this simulator, total protein is set at about 0.8 g/kg of body weight (precisely: 0.79 g of digestible protein) as the minimum requirement, but that is not a statement about anyone’s actual requirement: eat more by all means - all that is shown here is how much of the amino acids taken in with the food covers human requirements, and what a minimum supply would take.

What can the simulator do?

The simulation is not after clinical precision, but an approximation. The foods it contains are therefore meant to be used creatively: “Beef fillet” stands in for reasonably lean meat (not for fancy expensive food), “Beef patty” is the fattier one. “Sugar” can stand in for jam, for example (56 % sugar, next to no protein), or together with “Oat flakes” for sweetened muesli.

Every value can be adapted to your own eating habits, and anyone who finds a food missing is welcome to leave feedback - or simply to pick a similar one.

The values are taken from the Bundeslebensmittelschlüssel (german language), the German national food composition database, and corrected for digestibility - that is, for bioavailability.

Where is the simulator?

In the menu under Simulation / Amino acids (where it has more room on a large screen). And right here:

Experiments

For every kind of diet:

How far is a diet from the minimum values it needs? Where a diet only just meets those minimums, everyday variation will break through them easily.

Since individual foods are so readily compared by weight: how much weight does a day’s food come to? The sample days are all normalised to about 2200 kcal, so that they can be compared.
What protein content covers the required values per 1 kg of body weight? For every one of the sample diets this already sits above the commonly recommended 0.8 g/kg - by a wider or narrower margin (between 0.83 and 1.73 g/kg)
Are there individual essential amino acids that fall below the minimum?
- Most of the presets are limited by total protein, not by any single essential amino acid. Worth exploring for yourself.
The values are arbitrary suggestions - I would positively encourage trying different variants: that is what the sliders and the further foods are for.
Portion sizes and body weight: the presets are all normalised to 2200 kcal, while body size - and with it, implicitly, calorie requirement - differs from person to person. If you adjust the body weight, portion sizes may need adjusting with it.

The DGE diet

The Deutsche Gesellschaft für Ernährung - German Nutritional Society, a largely government funded NGO, designated as appointed authority on nutritional matters advises limiting meat to 300 g per week. The ration carries the daily average of 40 g - certainly unrealistic as a single portion: hidden in a salad, that much would be all but undiscoverable.

What does a meat-free day look like? Nobody weighs out 40 g a day - but we have no protein stores worth mentioning that could even out a shortfall across the week.
- This matters especially because suddenly it is not only total protein but also one of the essential amino acids that falls below the daily requirement. Even with that small amount of meat these were only just above the minimum values - so there is barely any room:
- 25 % of the lysine, then, is carried by 2.5 % of weight and of calories in the food - a small change to a recipe has remarkably far-reaching effects.

Vegan diets

What is particularly interesting are the different protein sources and how differently they are equipped with amino acids. Three variants (“Vegan, considered”, “Vegan, everyday” and “Rice + beans”) are provided.

Cereal-based diets

The “Cereal day” is there to visualise the poor quality of the amino acid composition in grain: what does it take to meet the body’s requirement on a lot of cereal?
- It pays to keep an eye on the calorie figure while dialing the input values to create a 100% amino-acid-sufficient diet.

Keto and carnivore

These diets contain a great deal of fat, which supplies considerably more calories per gram. What is interesting here is the weight of food required, which comes to roughly 40 % to two thirds of the plant-heavy diets. That puts some comparisons of animal with plant foods into perspective, given that they are usually quoted per kg of weight
- Example: how much rice versus how much meat do I need to cover a complete profile? (an unfair comparison - but one the other side is fond of making too. Compare the foods you actually want to compare)

What does it not simulate?

The simulator deliberately restricts itself to the essential amino acids required and to total protein. It says nothing about calorie requirements or about any other micronutrients, minerals, vitamins and so on - a diet shown as “complete” in this simulator is complete only with respect to its (idealised) protein composition, and is not a general dietary recommendation.