Everything You Want to Know About Protein and More

What protein is made of, how much you need to eat, how your needs change with fat loss and ideas for how you can get more protein in your diet.

What Protein is and Why it's Important

Protein is the basic structural component of the body. It carries out a lot of jobs and, most famously forms muscle. Protein is essential, which means you can't survive without it.

What are Proteins Made of?

Proteins are made up of one or more chains of amino acids. Amino acids are organic compounds with varying structures that combine to form proteins. The shape an amino acid takes dictates its function.

The human body uses 21 different kinds of amino acids.

There are two main groupings of amino acids, nonessential amino acids, those that your body can make on it's own and essential amino acids, those that your body needs to get from your diet.

The Essential Amino Acids:

  • Histidine
  • Isoleucine
  • Leucine
  • Lysine
  • Methionine
  • Phenylalanine
  • Threonine
  • Tryptophan
  • Valine

The Nonessential Amino Acids:

  • Alanine
  • Arginine
  • Asparagine
  • Aspartic Acid
  • Cysteine
  • Glycine
  • Glutamic Acid
  • Glutamine
  • Proline
  • Selenocysteine
  • Serine
  • Tyrosine

There is also a third class of amino acids that are conditionally essential. They become essential in special circumstances like when you're stressed or ill.

Conditionally Essential Amino Acids:

  • Arginine
  • Cysteine
  • Glutamine
  • Glycine
  • Proline
  • Serine
  • Tyrosine

Proteins are constantly being made and broken down in a process called protein turnover. The actual recommendation for protein is moreso a recommendation for amino acids. These amino acids combine with the ones consumed in your diet to form what’s known as an amino acid pool.

Because amino acids and protein exist in a pool, it means they don't need to be present in every meal but, they should be present overall throughout your day. The amount of protein present in your body at any time is your net protein balance.

If you would like to read more on the chemistry of amino acids and protein structure, Khan academy has a great resource on this here.

Why Protein is Important

Protein is responsible for a lot of different things in the body.

A few ways protein functions in the body include:

  • As an enzyme-assisting in breaking down and building things in chemical reactions
  • As a hormone-chemical signals the body uses to communicate, some hormones are proteins
  • In transportation-hemoglobin, a protein, carries oxygen throughout the body
  • As a structure-forming the contractional component of muscle mass as well as forming skin and bone.
  • As antibodies-protecting the body from infection and disease.
  • As energy-protein can be used as fuel and converted into glucose if needed.

Without protein, there are a lot of functions that your body will not be able to carry out.

How Much Protein do You Really Need?

How much protein you need depends on a few things. Several factors affect how much protein you need including:

  • The quality and digestion of protein-more on that later
  • The size of the individual
  • Your Age
  • Whether you're pregnant or nursing
  • Whether you're active or not
  • The types of activities you do, if you are active
  • If you're dieting and in a caloric deficit

We'll look at a couple specific examples later like weight loss and gain but, for now, just know it depends.

One factor that also affects the amount of protein you need is actually something science can't tell you directly. It's known as intrasubject variability. What is intra-subject variability? Intrasubject variability basically means that there was variability in a study group.

Over the broad majority of the population they've come up with figures that work. There are however cases where people seem to respond better or worse to the same variable as others. Some people do better on lower carb diets vs lower fat diets for example. Those broad recommendations are known as Dietary Reference Intakes or DRIs.

Dietary Reference Intakes

One of the DRIs is your RDA. The Recommended Daily Allowance (RDA) is the minimum amount of a nutrient that you need in order to not get sick. It varies for age and sex. It is assumed that you are already healthy and do not have special needs.

The current RDA for protein for adults is 0.8 grams of protein per kilogram of body weight. If you don't use the metric system (what the metric system is and why it's cool), that comes out to 0.36 grams of protein per pound of bodyweight.

Acceptable Macronutrient Distribution Ranges tell us how much a given nutrient is generally allowed to take up a portion of your diet. AMDR is a little more useful than a DRI because it takes high or low calorie diets into account. The ranges account for reducing chronic disease and risk.

For protein the current AMDR guidelines are:

  • Young Children (Ages 1-3)- 5-20%
  • Older Children and Adolescents (Ages 4-18)- 10-30%
  • Adults (Age 19+)- 10-35%

Again these numbers represent very general ideas of the amount of protein you can eat for health. There are a few concerns about the RDA for protein. In Essentials of Strength Training and Conditioning, Marie Spano, MS, RD, CSSD, CSCS notes:

"Some scientists suggest that adults should consume more than the RDA for bone health, weight management, and building and repairing muscle. In addition, research suggests that higher-protein, lower carbohydrate diets can favorably affect blood lipids, particularly in obese individuals, and therefore also decrease some of the risk factors for cardiovascular disease and metabolic syndrome."

If you would like to find out specific information on your own DRIs, the USDA has developed an interactive calculator you can use and find here.

Your RDA does not take into account activity. It also assumes that you're eating quality protein sources which is the next thing we'll cover.

How Do You Measure Protein Quality?

Protein sources are ranked in various ways by bioavailability. Bioavailability is a measure of digestibility and quality or the amount of amino acids present in a protein containing food that can be used by the body.

The Major protein quality measures include:

  • Protein Digestibility Corrected Amino Acid Score (PDCAAS)
  • Protein Efficiency Ratio (PER)
  • Biological Value (BV)
  • Net Protein Utilization (NPU)

Protein Digestibility Corrected Amino Acid Score

Protein Digestibility Corrected Amino Acid Score is the current "gold standard" accepted by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO).

PDCAAS is based on the human amino acid requirements of preschool aged children and takes the number of limiting amino acids into account. A limiting amino acid is the essential amino acid found in the smallest quantity in a food.

Once the limiting amino acid score is determined, it is compared to a high quality reference protein and a score is given.

According to the Journal of Nutrition, linked above in the headline;

"PDCAAS values higher than 100% are not accepted as such but are truncated to 100%. Although the principle of the PDCAAS method has been widely accepted, critical questions have been raised in the scientific community about a number of issues."

It is for this reason that the FAO proposes a new measure you can read about here called the Digestible Indispensable Amino Acid Score (DIAAS).

Protein Efficiency Ratio

Protein Efficiency Ratio is a measure of growth per gram of digested protein. It is typically determined using rodents. The value measured is compared to casein protein which has a score of 2.7. Anything over 2.7 is considered excellent quality. Tricky because rodents have different amino acid requirements.

Biological Value

Biological Value is also determined using rodent studies. Biological value measures protein quality by calculating the amount of nitrogen used for tissue formation divided by the nitrogen absorbed from the food.

The amount of nitrogen and nitrogen in the tissues gives a score that is expressed as a percentage. A food that has a high value correlates to a high supply of amino acids.

There are a few problems with using this system as well.

This entry from the Journal of Sports Science and Medicine notes that;

"The biological value does not take into consideration several key factors that influence the digestion of protein and interaction with other foods before absorption. The biological value also measures a protein’s maximal potential quality and not its estimate at requirement levels."

Net Protein Utilization

Net Protein Utilization is similar to Biological Value but, it factors in the amount of nitrogen excreted by the body by direct measurement. BV is calculated via nitrogen absorbed, NPU is calculated by nitrogen ingested.

Unlike BV, NPU corrects for utilization but, it is still based on rodents.

High PDCAAS Scoring Foods/Supplements

PDCAAS ranks foods a score that ranges from 0 to 1. Animal proteins rank the highest in PDCAAS scores.

Some high scoring sources include:

  • Casein (milk protein)-1.00
  • Egg-1.00
  • Whey (milk protein)-1.00
  • Soy Protein Isolate-1.00
  • Mycoprotein-0.99
  • Beef-0.92
  • Pea Protein Concentrate isolate-0.893
  • Black Beans-0.75
  • Peanuts-0.52
  • Rice-0.50
  • Wheat Gluten-0.25

Important to note, this score does not mean that a source like a plant is not a complete protein, it is a measure of the proportion of amino acids.

A complete protein contains all of the essential amino acids in adequate amounts. Incomplete proteins are missing one or more of the essential amino acids. Complementary proteins are two or more proteins that can be eaten in combination to form a complete protein.

An example of two otherwise incomplete proteins that form a complete protein is beans (low in methionine) and rice (low in lysine).

Are BCAA supplements a good amino acid source? Yes and no, recent research says that they're kind of useless when enough protein is present.

Why You Need Protein When Losing Unwanted Weight

Muscle is very important for your appearance. If you want to appear more toned as you lose fat, then you have to keep the muscle you do have, while you decrease the amount of fat you carry. This means you need to eat enough protein to help spare muscle as a fuel source.

Your protein needs actually increase when you're attempting to lose weight. Reason being, when you're consuming less energy (calories), your body does not have enough protein coming in to replenish your amino acid pool.

The International Society of Sports Nutrition reflects this change in a position stand (statement based on solid research and scientific data) noting;

"Daily intakes of 1.4 to 2.0 g/kg/day operate as a minimum recommended amount while greater amounts may be needed for people attempting to restrict energy intake while maintaining fat-free mass."

This means that our minimum intake of protein would increase from 0.36g/lb/day to .635-.907g/lb/day, more than double, just to be healthy while dieting.

Remember if you add any other piece to this puzzle like exercise, that will further increase the amount that you need. There may be an optimal number in each special circumstance for you.

Protein is the most satiating macronutrient which is great for dieting, the more you eat calories from protein while dieting, the more satisfied you'll feel. That likely makes it a little easier for you mentally to stick to your diet.

How Much Protein You Need to Gain Muscle

I'm going to lean on the International Society of Sports Nutrition position stand for a couple points here on optimal protein intake for a couple populations. The amount of protein you need can get pretty complicated and nuanced.

For the athlete:

"Recommendations regarding the optimal protein intake per serving for athletes to maximize MPS are mixed and are dependent upon age and recent resistance exercise stimuli. General recommendations are 0.25 g of a high-quality protein per kg of body weight, or an absolute dose of 20–40 g."
  • MPS-muscle protein synthesis, the process of building muscle from proteins.

The ISSN took this position because it is difficult to nail down the complex needs of people exercising. All of the factors mentioned in the "How Much Protein Do You Really Need" section above come into play!

Take age for example when the ISSN position stand gives a recommendation for the elderly:

"Higher doses (~40 g) are likely needed to maximize MPS responses in elderly individuals."

There is a good amount of variation between populations. To be safe, if you're trying to build the most muscle possible, you'll likely want to shoot for the upper ends of protein consumption recommendations.

How high? The ISSN has us covered.

"There is preliminary evidence that consuming much higher quantities of protein (> 3 g/kg/d) may confer a benefit as it relates to body composition."

Is there a special time that you need to eat protein?

Protein Timing for Fat Loss and Body Composition

You can be at a negative and positive protein balance at any point in the day. Overall however, it appears that protein meal timing and frequency does not have much effect on fat loss or body composition. This means that on a normal day, you can likely spread your protein out evenly to no ill effect.

Protein Timing Around the Workout Window

Does when you eat protein make a difference in your workout results? Not as much as you might think.

This meta-analysis explored in the link post above, examined the effects of protein timing on muscle strength and hypertrophy immediately around the workout window. The researchers found no meaningful differences between waiting a bit and eating right away. The only measurable differences in the studies came when the subjects ate more protein overall.

That likely means there's no special advantages to slamming protein a shake right after your workout.

Ultimately, as long as you get enough protein, it does not matter much if you eat protein before or after exercise!

What are Good Supplements and How do you Pick One?

Protein is not needed as a supplement per se but, a protein supplement can be a good convenience product. Be sure that a majority of your protein comes from whole food sources before considering this.

Are amino acid supplements or BCAAs considered protein?

First, BCAA supplements are a waste of money. A summary of the research on this can be read here.

Why Supplementing Protein Might Be A Good Idea for You

Protein supplements make for good convenience products. This is more about knowing yourself than anything else.

Reasons to consider supplementing protein:

  • You're a vegan
  • You are short on time and have a tendency to skip meals
  • You have a hard time stomaching a full meal in the morning

A good protein supplement is one that supplies you with a good amount of grams of protein per scoop as well as a good amount of one of our essential amino acids, leucine. Leucine has been shown to be one of the most important amino acids in the muscle building process.

Most supplement companies are aware of the importance of leucine and do a fair job of ensuring that they include it in their products. Some protein brands are difficult to diagnose because they do not disclose their formulas and ingredients openly, opting to write "proprietary blend" on their labels.

What Kinds of Protein Powders are Out There?

There are different kinds of concentrations of protein powders. Some you may have heard of include:

  • Concentrates
  • Isolates
  • Hydrosolates
  • Combination Proteins

The differences here are the amounts of processing utilized. The more processed the protein is, the more other non-protein components are removed. The highest form is an isolate. For example, Isolated Soy Protein contains 90-95% protein.

Hydrolysates are partially broken down for easier digestion. You're likely don't need anything more than a good protein isolate.

Different types of protein powders: (This is not intended to be an all extensive list)

  • Whey protein
  • Soy Protein
  • Egg Protein
  • Casein protein
  • Beef protein
  • Pea
  • Hemp
  • Brown rice
  • Milk protein Isolate: Contains both Casein and Whey proteins in their natural ratios of 80/20 casein-to-whey respectively.

Examine.com has put together an extensive summary of the body of research on whey, casein, hemp and milk protein if you would like further reading.

How to Pick a Good Protein Powder

Picking a protein powder can be tricky since the FDA regulates supplements like foods, it assumes they are all safe until research proves otherwise. In the meantime you are left guessing at what is really in each scoop.

Some rely on using only well established companies that are known to have good practices. That is one way to go about it. I don't feel like that ever gives newer businesses a fair shake so here are some other ideas.

Three things to look for in a protein supplement:

  1. Independent lab testing
  • These labs keep tabs on supplement companies, performing tests on products from multiple sources ensuring they contain what they say.
  • Look for "USP" or "USP Verified", "NSF" or products verified by consumerlab.com
  • What if a product does not contain one of these? Then it may still be safe but, its all guessing at this point.

2. Protein per gram- The amount of protein per gram serving.

3. Artificial sweeteners or additives

  • There can be some give and take here. You are not buying a supplement for it's taste but understandably taste is a factor. If you had the best protein powder in the world but could not stomach the taste then you likely won't take it.

Another consideration is digestion. If you find that certain types of protein are harder on your GI (digestive tract) and cause you to feel bloated then you may avoid them. An example of this is proteins containing milk for those with lactose intolerance.

What I've personally used:

Note: I have some recommended supplements here.

Nature's best Isopure Cookies and Creme Flavor-It's a Whey Protein Isolate that contains no carbs and about 82% protein. You have to be careful even among brands. I picked this flavor because some of the others have less than 80% protein and that was important for me.

Dymatize ISO100 Whey Protein-Dymatize is a solid brand that actively funds unbiased research in the strength and conditioning field. They have a number of solid flavors that contain around 83% protein (25g per 30g scoop).

Gold Standard 100% Whey-the most economical of these three choices is Gold Standard. If you're looking for a solid whey, this may likely be your choice. There are a few flavors including double-rich chocolate that contain about 79% protein.

What you take is ultimately up to you. The links included above are non-affiliate (Missouri is a nexus state). Bodybuilding.com is the website linked where I've found some of the best priced supplements online.

If you feel like a protein powder is making unrealistic claims, that's a red flag. You can read up on the USDA's supplement advertising guidelines here.

What Happens if You try to stuff Yourself with Protein?

You'll instantly turn into a bro. Ha! It's actually very hard to eat "too much" protein. Upon the rise of popular higher protein diets, this was a concern voiced that has largely been disproven.

Could You Damage Your Kidneys?

This study review notes that this is not really a problem if you have normal functioning kidneys.

In the review, the effect of high protein diets consisting of 1.5g/kg/day or 0.68g/lb/day was examined on renal function, particularly in people with renal disease. There were no increases in the risk of kidney disease.

What about athletes and people eat more protein than that? Even athletes who consumed 2.8g/kg/day or 1.27g/lb/day were examined and were at no greater risk for kidney disease or loss of function.

If you weighed 150 lbs that would be 190g of protein in a day. To convert that over to food, an ounce of meat has about 7g of protein. That translates to 27.2 ounces of meat.

It will also be very hard to each too much protein because of the satiating effect mentioned. You'll feel stuffed long before you reach that many grams in one day.

As long as you are not limiting the amount of other macro and micronutrients you need in your diet, you're more than fine eating more protein.

Do You Need Real Advice on How to Get more Protein?

Preferably your protein will come from whole food sources like those listed above. There several ways to include more protein dense foods in your diet. Let's walk through a few ways to add in some here.

Find Delicious Ways to Prepare Your Protein:

Even if you eat the same source of protein, preparing it in different ways can help you stick to eating these foods.

Here are some recipes that I have tried and like:

Creative Ways to Use Protein Powder

If you're looking for some creative ways to use your protein powder a good resource is proteinpow.com

Here are some recipes you can find on proteinpow.com

An additional way to add more protein to your diet includes swapping out some ingredients in recipes.

Swaps that Deliver More Protein

Swap out sour cream for greek yogurt cooking-per 100 grams:

  • Greek yogurt:
    • 59 calories
    • 10 grams of protein
    • 0.4 grams of fat
    • 3.6 grams of carbohydrate
  • Sour cream?
    • 193 calories
    • 2.1 grams of protein
    • 20 grams of fat
    • 2.9 grams of carbs.

Swap out rice for quinoa (a complete protein)-per 100 grams cooked:

  • Quinoa:
    • 120 calories
    • 4.4 grams of protein
    • 1.9 grams of fat
    • 21.3 grams of carbohydrate
  • Rice-long grain, white:
    • 130 calories
    • 2.7 grams of protein
    • 0.3 grams of fat
    • 28 grams of carbohydrate

Swap out a popular snack for more protein (unless you don't have a fridge:

  • Cottage Cheese 4 oz:
    • 111 calories
    • 13 grams of protein
    • 4.9 grams of fat
    • 3.8 grams of carbohydrate
  • Almonds 1 oz:
    • 163 calories
    • 6 grams of protein
    • 14 grams of fat
    • 6 grams of carbohydrate


  • Schoenfeld BJ, Aragon AA, Krieger JW. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. Journal of the International Society of Sports Nutrition. 2013;10:53. doi:10.1186/1550-2783-10-53.
  • Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition. 2017;14:20. doi:10.1186/s12970-017-0177-8.
  • Dieter BP, Schoenfeld BJ, Aragon AA. The data do not seem to support a benefit to BCAA supplementation during periods of caloric restriction. Journal of the International Society of Sports Nutrition. 2016;13:21. doi:10.1186/s12970-016-0128-9.
  • Brad Jon Schoenfeld, Alan Albert Aragon, James W. Krieger; Effects of meal frequency on weight loss and body composition: a meta-analysis, Nutrition Reviews, Volume 73, Issue 2, 1 February 2015, Pages 69–82, https://doi.org/10.1093/nutrit...
  • Aragon AA, Schoenfeld BJ, Wildman R, et al. International society of sports nutrition position stand: diets and body composition. Journal of the International Society of Sports Nutrition. 2017;14:16. doi:10.1186/s12970-017-0174-y.
  • Hoffman JR, Falvo MJ. Protein – Which is Best? Journal of Sports Science & Medicine. 2004;3(3):118-130.
  • Schaafsma, Gertjan. “The Protein Digestibility–Corrected Amino Acid Score.” The Journal of Nutrition, vol. 130, no. 7, ser. 1865S-1867S, 1 July 2000. 1865S-1867S, jn.nutrition.org/content/130/7/1865S.long.

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Steven Mack is founder and a Certified Strength and Conditioning Specialist at the private training studio, Simple Solutions Fitness. He consults for Stronger by Science, a leader in fitness research dissemination, and is a former Mizzou football walk-on. Steven dedicates his professional life to helping people through his writing, speaking, and role as a personal trainer.