First, let’s understand exactly how we are determining “highest protein content” of a given food.
To determine how much protein content a food has, you have to look at the percentage of total protein in relation to the rest of the macro-nutrients in the food (carbohydrates and fats) and things like fiber, water and vitamin and mineral content (yes, vitamins and minerals weigh something — just not very much.)
This will give you the “absolute” percentage of protein in a food and let you compare apples-to-apples … sort of.
Some High Protein Content Foods Compared
Let’s look at a few of foods with reputations for having a high protein content.
In all of these cases, we’ll be using a 50 gram serving or sample of the food to determine its percentage of protein. I’ll also use the raw form of the food, since the amount of water in a food can change its percentage of protein by weight after cooking. The goal here is to keep everything as equal as possible.
I’ve only included one non-animal source of protein (soy isolate), because in general, plant sources of protein don’t rank as high in total protein as animal or seafood/fish sources. So we won’t even bother with them (although they are still good for you.)
The key metric to look at with each of these foods is the percentage of total protein by weight, which is the last figure given for each food.
Eggs are one of those foods that always makes the top five list when it comes to high protein content. Here’s what eggs look like from a nutritional standpoint:
One large, whole raw egg (50 g) has the following nutritional profile:
- Fat: 5 grams
- Carbohydrates: 0 grams
- Protein: 6 grams
Protein Percent by Weight: 12%
Chicken breast is a staple of bodybuilding building diets because it’s considered very high in protein. Here’s what a 50 gram serving of chicken breast looks like from a protein perspective:
- Fat: 0.6 grams
- Carbohydrates: 0 grams
- Protein: 11.5 grams
Protein Percent by Weight: 23%
Ground Sirloin (95% Extra Lean)
Lean beef is another food that is considered very high in protein. Here’s what 50 grams of extra lean ground sirloin looks like:
- Fat: 3 grams
- Carbohydrates: 0 grams
- Protein: 12.9 grams
Protein Percent by Weight: 25.8%
Raw Yellowfin Tuna Steak
Among fish, tuna is one of the highest protein foods:
- Fat: 0.5 grams
- Carbohydrates: 0 grams
- Protein: 11.7 grams
Protein Percent by Weight: 23.4%
Soy Protein Isolate
Soy beans, in particular the concentrated powder form, are plant source of protein that also has a reputation for being high in protein:
- Fat: 1.7 grams
- Carbohydrates: 3.7 grams
- Protein: 40 grams
Protein Percent by Weight: 80%
Whey Protein Isolate
Finally, let’s take a look at a 100% whey protein powder (I used Iso Pure Whey Protein Isolate for the comparison):
- Fat: 2.7 grams
- Carbohydrates: 1.8 grams
- Protein: 39.3 grams
Protein Percent by Weight: 78.6%
Okay, so it looks like you win.
Compared to the eggs, the whey protein has the highest percentage of protein by weight (although technically, the soy isolate has the most.)
But before you declare outright victory, let’s take a closer look at some other factors you need to consider when determining which food really has the highest protein content.
Percentage of Protein Isn’t The Whole Story
Here’s where things get a little trickier.
First, the whey protein is the highest in protein by weight because all of the water and most of the fat and carbs that are in the liquid dairy whey have been removed through filtering and drying. If you removed the fat and water from the other foods, including the eggs (which have a very high amount of water content), you’d start to see their protein percentages by weight start climb.
So it’s a little unfair to compare a concentrated protein product like whey isolate powder or soy protein isolate to eggs or whole food sources of protein. They will always win out, because they’re more concentrated.
It’s Not Just the Highest Protein Content, But Also Protein Quality That Matter
Second, you also need to look at the quality of protein in a food, not just the quantity.
In the past, protein quality was measured using something called biological value (BV.) However, in recent years, nutritionists and scientists have started to use something called the Protein Digestibility-Corrected Amino Acid Score (PDAAS). While there are still a few kinks in PDAAS, in general, it’s recognized as the most accurate measurement of overall protein digestibility in foods.
PDAAS uses a 0-1 point scale, with 1.0 being the most digestible protein and zero being the least. You can roughly translate this into a percentage of protein digested. So if eggs have a PDAAS of 1.0 and wheat gluten has 0.25, then 100% of egg protein is absorbed by the body by weight, versus only 25% of the protein in wheat gluten.
Plant sources of protein like wheat gluten, vegetable proteins, and nut proteins usually have the lowest PDAAS and milk, eggs, whey and soybeans have the highest.
Practically speaking, this means that even though a 50 gram serving of extra-lean beef may have more overall protein than the same amount of egg, the actual amount of protein that gets absorbed by the body is very different.
To illustrate this let’s compare beef and eggs. According to the PDAAS, 100% of egg protein is digested by the body, while only 92 percent of the protein in beef is absorbed. So for that 50 gram serving of eggs, 6 grams of protein are actually usable by the body, versus 11.8 grams of the beef’s total 12.9 grams of protein.
If you adjusted the total amount of protein consumed to be equal between the two (disregarding the weight), gram-for-gram your body would utilize more of the egg protein than the beef protein.
What about the whey?
Whey protein isolate is more or less equal to eggs and soy protein in term of protein digestibility. It has a PDAAS of 1.0 — placing it on par with both of those foods. Milk and casein protein also have get a 1.0 score.
This is an important distinction from both a nutrition and economy standpoint — since it’s not how much proteinyou consume that’s important, but how much of that protein your body is able to use that matters.
Also, when making decisions about where to spend your money, knowing the actual efficiency of the protein you are eating can change what you buy.
For example, meat tends to be more expensive than eggs, so you can actually get more overall protein for your money if you buy eggs instead of things like chicken breast or beef. When you do the math, you’ll actually find that whey isolate or concentrate is actually the most cost-effective of all sources of dietary protein.
Problems With This Bet
The biggest issue with this bet is that you are comparing a dehydrated source of protein (powdered whey) against a fully hydrated food (eggs.) This will effect its total percentage of protein and can be misleading. You run into the same issues with meats, since they also contain some water and fat — which the powders don’t have.
If you compare dried eggs to whey, the picture changes. For example, a standard scoop of Optimum Nutrition 100% Whey Protein Powder has 24 grams of protein. A scoop of the same amount of ON 100% Egg Protein powder has 22 grams of protein. So it’s almost a wash.
So Who Wins the Bet: What IS The Highest Protein Content Food?
I’m going to call this a draw here, because you are both kind of right.
In terms of whole-food, non-concentrated sources of protein, the highest protein content food gram-for-gram that’s also highly-available to the body would be eggs.
Now, if you included concentrated forms of protein like whey isolate or soy isolate in the mix, the whey and soy win gram-for-gram compared to the whole food source. They have the highest protein content, since their percentage of protein by weight is 78.6 percent and 80 percent respectively, and both are 100% bio-available to the body.
One more note: Even though this comparison showed the soy protein having slightly more protein by weight than the whey, it’s important to understand this will vary from product-to-product. The two are so close, that I would consider whey isolate and soy isolate more or less equal.
So if you simply wanted to bet on which food — eggs or whey powder — had more protein content by weight, then you would win, Josh. But it’s not really a fair comparison and I don’t think that’s what you guys were actually trying to determine here.
Now that you know why, my advice would be to shake hands, split the $25 dollars and go buy some protein.