Protein Explained

Protein is colloquially considered the most important of the three primary macronutrients.

This is not an unreasonable statement to make, given its importance and the fact that the average american chronically under-eats protein. [1]

With that said, there is a great deal misinformation surrounding protein, and understanding what this article will explain will make optimizing your personal protein intake simple.

Here, I hope to provide you with the details on protein intake that will materially improve your life, and leave out the details that are unlikely to be of benefit to you.

So, the aim of this article is to cover the following:

• What is protein?

• What does protein do in the body?

• How much protein do you need?

• What makes a protein “good?”

• When is it best to eat protein?

• Whole food sources of protein

• Supplemental sources of protein

As always, if any questions are left unanswered, feel free to comment below and I will get back to you as soon as I am able.

What is protein?

A protein is a chain of smaller compounds called amino acids.

It can be imagined as beads on a chain, where each individual bead is an amino acid and the chain overall is the protein.

Different proteins differ based on the different amino acids they are comprised of.

There are 20 different amino acids; 9 of which our body cannot produce on its own and we must get from our diet.

These amino acids that our bodies can’t make are termed the Essential Amino Acids (EAAs).

This will be an important point when we discuss higher versus lower quality proteins.

What does protein do in the body?

It’d be easier to list off the things that protein does not do in the body.

Most people only think of muscle tissue when they think of protein, but the role of protein stretches far beyond this.

For instance, protein is the major structural component of things like tendons, ligaments, bone, etc.

Many hormones, like insulin, are also comprised of amino acids.

And, yes, after a workout, protein helps aid in the recovery and adaptive process that follows.

To list off all the places where protein / amino acids play a vital role would make this article ridiculously long, and understanding it all probably isn’t to your benefit.

To say protein does damn near everything is a perfectly acceptable take-home from this section.

Calorie content of protein

There are 4 calories in every gram of protein.

So, if you eat 25 grams of protein, you’ve consumed 100 calories.

However, there are two key features to protein that make it a unique source of calories as compared to carbohydrates or fats.

First, the thermic effect of protein is higher for protein compared to other macronutrients.

The thermic effect of food is how much energy (how many calories) your body must spend to fuel the digestion of food.

There are various factors that influence the thermic effect of food, and the macronutrient composition of food is one of them.

So, in other words, when you eat a meal or a food that is high in protein, your body will burn more calories to fuel the digestion of that food. [13]

Second, protein seems to be more satiating than carbohydrates or fats.

When you consume a meal that is higher in protein, there tends to be a greater release of the hormones that make you feel full. [14]

In practice, this intuitively makes sense. If you were to imagine eating 300 calories of chicken breast as compared to 300 calories of a sugar cookie, you’d inherently guess that the chicken breast would leave you feeling fuller.

So, yes, protein does count toward your total daily calorie intake.

However, there are clear advantages to having a high number of your calories come from protein itself.

How much protein do you need in a day?

This has been a debated topic for quite some time, and a wide range of numbers has been suggested.

For instance, the recommended dietary allowance (RDA) for protein is 0.8 grams per kilogram body mass (.36 grams per pound bodyweight).

Conversely, old school fitness lore will tell you to aim for 2.2 grams per kilogram body mass (1 gram per pound bodyweight).

For a person weighing 200 pounds, the RDA tells you to eat 72 grams of protein but broscience tells you to eat 200 grams of protein.

Clearly, this is a massive difference.

So, let’s look at what the evidence says on the topic.

One of the most famous papers on this subject is a systematic review with meta-analysis from Morton et al. [1]

They looked at the effect of different protein intakes on adaptations to resistance training (lifting weights).

The primary take-home was the 1.6 grams per kilogram of body mass (0.72 grams per pound of bodyweight) was the cut off.

In other words, eating more did not provide more benefit but eating less seemed to provide less benefit.

More recently, another paper on protein intake was published focusing more on endurance athletes. [2]

The primary conclusion from this paper was that 1.8 grams of protein per kilogram of body mass (.81 grams per pound of bodyweight) led to greater endurance adaptations and better recovery compared to lesser intakes.

The optimal protein intake was suggested to be even higher during more intense periods of training, such as peak week before a race, or during periods of carbohydrate restriction. In such instances, 2.0 grams per kilogram body of body mass (.9 grams per pound of bodyweight) may be better.

All of my clients are people who undergo both strength and endurance training, which is something I recommend everyone do in some way, shape, or form.

To date, there are no papers looking at the optimal protein intake in hybrid/concurrent trainees such as this.

However, it’s reasonable to think that such individuals would be better off erring on the side of ~1.8 g/kg (.81 g/lb).

As an aside, you can assume these dosages would be appropriate for states of injury as well.

Recovery from an injury isn’t all that different from recovery from a workout; the primary difference is the time required to recover.

Something else to keep in mind here is that body composition matters also.

A person with a lower body fat percentage will have to eat a higher amount of protein relative to their bodyweight compared with a person with a higher body fat percentage.

In other words, 1.6 g/kg might be a good target for someone with a body fat percentage of 30% but not enough for a person with 15%.

In an ideal world we’d be able to make recommendations based off of lean body mass (non-fat tissue), but reliably and consistently measuring body composition is an impractical thing to do.

Furthermore, there is some wiggle room here in terms of getting “good enough.”

For instance, in the Morton et al. meta-analysis, a high amount of the benefit from protein was seen when subjects ate 1.2 g/kg or more. From here, there was a slight uptrend of benefit toward 1.6 g/kg where it tapered off.

The same relationship would likely be seen in endurance athletes.

So, if you’re trying to figure out how much protein you should eat in a day, take these numbers as a starting point.

Adjust them up or down based on the results you see and what you can reasonably adhere to long-term.

What makes a “good” protein?

As we mentioned earlier, 9 of the amino acids are essential; meaning our bodies cannot make them on their own.

If a food contains all 9 of the amino acids, it is considered a “complete protein.”

If a food is missing one or more of these essential amino acids, it is considered an “incomplete protein.”

Generally speaking, animal foods tend to be complete protein sources and plant protein sources tend to be incomplete protein sources.

At face value, this would lead you to view animal proteins as inherently better than plant proteins.

However, evidence on the subject suggests that a person following a plant-only diet will see similar results in muscle growth compared to omnivorous diets if enough total daily protein is eaten. [3,4]

Another point to consider is the total number of calories relative to the amount of protein that a food has.

If a food has a high amount of protein compared to a low number of calories, then it can be said to be a good source of protein.

Comparing chicken breast and peanut butter makes this easy to see, and it is fitting given that some folks still view peanut butter as a good source of protein.

100 grams of chicken breast will run you 22 grams of protein and 100 calories or so. 100 grams of peanut butter will also run you 22 grams of protein but come with about 600 calories.

• Side note: 100 grams of peanut butter is a boat-load of peanut butter. I just used 100 grams to make the direct comparison.

Don’t get me wrong, the protein from peanut butter would still count toward your daily intake, it’s just not the most appropriate to consider peanut butter a source of protein specifically given the high number of calories it has relative to its protein content.

This is another common downfall of many plant-based sources of protein; they may come with a higher number of calories.

That said, there does seem to be a notable health benefit to be had from having a good portion of your calories come from plant sources.

I discuss the nuance of plant versus animal protein in full detail here.

Does when you eat protein matter?

The timing of your protein intake is worth considering, but it should not be a primary goal.

Here’s what I mean:

Protein is unique as compared to carbohydrates & fats insofar that our bodies have no real means of storing it and using it for later.

Similarly, muscle is in a constant state of being built up and broken down. Protein intake stimulates the building side of this equation, but the effects last for a few hours or so.

It is for these reasons that it is often considered best if your protein intake is spread out somewhat evenly across the day. In other words, divide your total daily protein intake into 3-4 servings per day instead of 1-2.

However, in studies where different frequencies of protein feeding is compared with total daily intake being the same, there tends to be very little difference. [5]

So, prioritize your total daily intake above all else. If that can be split up into multiple feedings in the day, great. If not, get your total intake in however you can. It is better to get your total daily intake in lesser feedings than to fall short of your total intake with more frequent feedings.

Another thought that has been proposed with regard to protein intake is the idea of an anabolic window. In other words, the idea that protein is more useful if consumed within 30-60 minutes of working out.

In my view, this depends on the workout.

For strength training, it does not seem to matter much, if at all. The evidence overwhelmingly suggests that if total daily protein intake is the same, then whether or not you consume protein within 30-60 minutes of strength training makes no difference. [6]

For endurance training, a different picture may be painted.

Cardiovascular exercise drains your fuel stores to a much greater degree than strength training does. For this reason, nutrient timing tends to be an important consideration.

There is no time window that is considered “optimal,” but consuming carbohydrates & protein together soon after an endurance training session is likely to lead to better results than not doing so. [7]

Protein intake and health

The effect of different protein intakes on health outcomes has been studied extensively.

In this section, I’ll briefly review some of the research on the more popular topics.

Protein & kidney health

The kidneys have been the most talked-about point of health when it comes to protein intake.

The rationale for protein’s implication on kidney health goes something like this:

• Amino acids (what make up protein) contain nitrogen

• If protein is broken down, the kidneys must excrete the nitrogen because nitrogen can be toxic

• Therefore, higher protein intakes make the kidneys work harder over time

From a purely mechanism point of view, this looks believable. However, you can rationalize anything if you focus on individual mechanisms in the body.

In May 2023, an umbrella review of systematic reviews (a study of studies of studies, basically) found that long-term kidney health and function is unaffected by protein intake in otherwise healthy adults. [15]

Watching protein intake may be worthwhile in the presence of active kidney disease, but there is no evidence to suggest that protein intake itself will cause kidney disease.

Protein intake and diabetes risk

Another umbrella review of systematic reviews was published in September of 2023 looking at the effect of protein intake on diabetes risk. [16]

Here, the authors found no relationship between high vs low protein intake and diabetes risk. There was some evidence to suggest higher consumption of animal protein leads to higher risk of diabetes as compared to plant protein, but this is more suggestive of factors apart from the protein itself that increases risk- such as saturated fat content.

That said, there is a reasonable argument to make that higher protein intakes, combined with resistance training, would lead to decreased diabetes risk.

It is well known that resistance training is massively beneficial for improving diabetes or decreasing risk of diabetes. [17]

There are a few reasons for this:

• The act of training itself tells your muscles to take up more sugar from your blood.

• Muscle is the primary source of carbohydrate storage in your body. If you have more muscle, you have more storage sites available.

• Muscle can release certain hormones (myokines) that stimulate the uptake of sugar from the blood.

The bottom line is that the act of training itself and the adaptation (having more muscle) is beneficial for reducing risk of diabetes.

Similarly, as we’ve discussed, higher protein intakes (~1.8g/kg) will improve the rate at which you build muscle and the amount of muscle you are able to build from resistance training.

So, it is not unreasonable to say that if higher protein intakes will help you build more muscle, then they are likely to reduce diabetes risk.

Protein intake and osteosarcopenia

Osteosarcopenia is a condition of decreased bone mineral density and muscle mass simultaneously.

This is a rather new term being used because the condition of decreased bone mineral density and age-related decreased muscle mass occur together quite often. [18]

With age, there tends to be a decrease in quality of muscle, quantity of muscle and bone mineral density.

However, there is some evidence that this has more to do with lifestyle than the aging process itself. [19]

In other words, as people age, they tend to become more sedentary. If your body has no reason to maintain muscle mass or bone, then it is not going to.

Yes, there is some resistance that comes with aging, but there seems to be far less than people think.

The most effective means to treat this condition is really quite simple: strength training and protein.

For instance, a 2020 randomized control trial [20] had older adults with decreased bone mineral density and muscle mass supplement with whey protein and resistance trained twice per week.

All subjects that underwent this protocol experience improvements in muscle mass and bone mineral density.

Although the strength training is integral to see benefits, the increased protein intake was also a vital player.

Bottom line:

There are many other conditions that I could go through, but the trend will remain the same.

In otherwise healthy individuals, there is no downside and only upside to having a high protein intake (>1.6 g/kg).

There are certain health conditions that may necessitate lower protein intake. If you have concerns, please consult your primary care physician.

Food sources of protein

Sources of protein from food worth your consideration include:

• Chicken

• Turkey

• Porkloin

• Red meat (leaner = better protein:calorie ratio)

• Fish (salmon, mahi mahi, snapper, swordfish, grouper, tilapia, etc.)

• Shellfish (e.g. shrimp)

• Yogurt

• Cottage cheese

• Eggs

• Tempeh

• Tofu

• Seitan

• etc.

Protein powder

Foods that are high in protein tend to be more filling and more work to prepare- making it hard for some to consume enough protein.

Protein powder serves to remove this friction from hitting your protein needs.

In regard to animal-derived protein powders, there are two that are by far the most common: whey & casein protein.

These are the two major proteins found in cow’s milk.

Whey protein is generally considered better than casein [8,9,10,11] and it usually costs less and tastes better.

If you have no allergies or intolerance to dairy, then whey protein would be a good choice of protein powder.

In regard to plant-derived protein powders, there are many different kinds available.

The most important thing to look for in a plant protein powder that a combination of different plant proteins are used, as this is one way to ensure all essential amino acids are present in the protein.

In general, though, plant protein powders tend to provide the same results and benefits as whey protein does [12].

Their primary drawback is that they taste much worse as compared to whey protein. I’m allergic to dairy and can tell you firsthand.

The only protein powder that would not be productive for the sake of building muscle or recovering from exercise in general would be collagen protein. I explain why here.

In any case, all other protein powders can be helpful for reaching your daily protein needs. It isn’t unreasonable to let taste and cost be your primary decision making criteria as to which you pick.