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Everything You've Ever Wondered About Protein — Answered

Lisa Hayim
Lisa Hayim
Registered Dietitian
By Lisa Hayim
Registered Dietitian
Lisa Hayim, M.S. R.D. is a wellness enthusiast. She received her master's in nutrition and exercise physiology from Columbia University.
Photo by Cameron Whitman

Protein is one of the three macronutrients, alongside carbohydrates and fat. All macronutrients are important and must be consumed to thrive. Both the proteins we eat and the proteins in our bodies are made up of small compounds called amino acids. Amino acids are often called the "building blocks" of protein because when amino acids get assembled together, they form a protein. It may be helpful to think of amino acids as the cars on the train. Each car is an amino acid, yet the whole train is the protein. Amino acids are strung together in a variety of ways and combinations. The final sequence of amino acids determines the protein's function, structure, and role in the body.

While there are tons of amino acids in nature, humans need only 20 of them. Nine of these are called essential, meaning we must obtain them through diet. When we consume proteins through food, our body breaks them back down into amino acids, which is the functional structure for how they work in the body. How does it work? When we consume food, our digestive enzymes get to work in both the stomach and intestines. They break down those proteins back to amino acids, which can be reused to make the proteins the body needs.

In the body, older proteins are constantly being broken down while the new ones we consume are being synthesized. Some of the amino acids obtained through the diet can also be spared for energy if the carbohydrate intake is too low. In other words, if you consume too few carbohydrates, the body is starved for energy and will break into the tissues and convert the amino acids to usable energy.

Why do you need protein?

Protein is behind all of our major bodily functions and is used every single day to keep the body going. It is most well-known and referred to in the context of growth and tissue/muscle repair, for those individuals who are very physically active at the gym or have undergone surgery.

However, it is also the backbone behind our skin, hair, our digestive enzymes, hormones, our neurotransmitters and our antibodies (which play a key role in our immunity). Protein is even a valuable part of making hemoglobin, the part of our red blood cells that brings oxygen all around the body. We also obtain vitamins and minerals from protein, such as those B vitamins that are essential for energy production. Once food is taken, protein is broken back down into amino acids, where they enter the bloodstream and eventually settle into tissues and fluids. When needed, we can reach back into our tissues and fluids into the stores to get the amino acids as they are needed. To make sure the supply of amino acids is steady and available, we must consume protein daily.

The caveat, however, is to space out the amount of protein consumed over the course of the day. This is because at each time, the body can only digest and use and store a certain amount of protein. The rest is broken down and excreted through the urine. In fact, too much protein in a diet may cause excessive urination.

Each person has a different threshold for how much their body can process at a time, but the average and most commonly recommended amount is no more than 30g of protein at each meal.

Alternatively, if we do not eat enough protein, our body will tap into our stores and start breaking down the protein in the body to release the amino acids needed to assist in the most vital body functions. That means that when your diet is inadequate in protein, it will break down skeletal muscle stores in an effort to keep you alive and to perform the vital body functions.

There are a ton of different types of protein to work into a diet.

For example, when we consume an egg, we take in a different combination of amino acids than when we eat lentils or drink a glass of milk.

Think about it. When you hear about consuming dairy, we hear about the proteins like whey and casein, but when we consume meat or seafood, we talk about proteins like collagen. Proteins of animal sources such as chicken, eggs, milk, fish, etc., are considered complete because they contain all the essential amino acids. Plant proteins, like those in beans and grains and soy, are lacking one or more essential amino acids and are therefore considered incomplete.

For example, grains can be low in the amino acid lysine (an essential amino acid) while beans are lacking in methionine.

However, vegetarians and strict vegans can work around this by consuming various proteins of proteins to complement one another and fill in the gaps.

If the person is plant-based, they have plenty of vegan sources like lentils, soy beans, and tofu. If they have no dietary restrictions, the options for protein expand much wider into beef, chicken, eggs, milk, etc.

The first way to choose protein is based on individual preferences, allergies, ethics, and goals.

The amount needed varies depending on the person's needs for repair. For example, someone in metabolic stress (when metabolism goes into a "shocked" state and the body has difficulty using its available sources energy; this is how the body responds to stress in an effort to protect itself) may need more proteins than a healthy individual.

Each food contains different amino acids. One of the suggested cons of plant-based proteins is the fact that you can’t get pure protein. Beans, for example, are a blend of carbohydrates, proteins, and very little fat, where a piece of skinless chicken can be almost entirely protein.

Additionally, it's important to note the importance of omega-3 fatty acids. Omega-3s are best known for their role in inflammation and must be consumed via the diet. Omega-3s come in three different forms, called ALA, EPA, and DHA. ALA must be converted to EPA to work to protect inflammation, and DHA is important for protecting the brain. While ALA can be converted to EPA, this conversion is very small, and therefore a lot of ALA would have to be consumed to get enough EPA. Most plant sources of omega-3s are ALA, while fish, eggs, and meat contain omega-3s. When it comes to getting the best omega-3s from your protein, the top two choices are grass-fed beef and wild-caught salmon.

There are also different types of protein supplements and protein shake powders, with different benefits and detriments.

These are a great way to make sure you're getting adequate protein in your diet since high-protein supplements contain a concentrated (and often balanced) profile of amino acids. Here's how to choose the best protein supplements for your body and needs.


Whey protein comes from cow’s milk. It is the liquid portion when milk is turned into cheese. You can find different flavors of whey powder—chocolate whey powder is a favorite of many of my clients. When you choose whey, always choose a grass-fed protein option.

Pros: Whey isolate is considered to be the superior option for athletes because it contains the highest amount of protein per serving. It is absorbed quickly into the bloodstream and used for muscle growth and recovery, strength improvement, and lean body composition. It is naturally complete with all the essential amino acids and is one the best sources of the three branched-chain amino acids including leucine, important for muscle development.

Cons: Contains dairy, may cause gas, often contains many artificial sweeteners, and is processed.


Like whey, this one is also dairy-based. The process involves separating the liquid milk from the carbohydrate and fat portion of the dairy. When you choose casein, always choose a grass-fed protein option.

Pros: Unlike whey, casein is digested over a long period of time. Many people who want to avoid muscle breakdown consume casein before bed to avoid a short "starvation" period during sleep that could affect the proteins stored in muscles.

Cons: Like whey, many people are allergic or intolerant. It is not ideal for a post-workout supplement because of its slow digestive time.

Egg-based protein.

Egg protein is a concentrated amount of the egg-white portion of the egg that is dehydrated and formed into a powder.

Pros: Relatively easy to digest and involves minimal processing.

Cons: Many people are allergic to eggs, and many find this supplement to be expensive. Depending on the egg it came from, it may contain hormones and antibiotics that were given to the hen.

Plant-based proteins.

Vary in composition but can contain pea protein, hemp, quinoa, soy, rice, etc.

Pros: Suited for vegans, lactose intolerance, vegetarians. When blending two or more of the different types together, you can get all essential amino acids. They are relatively easy to digest and better for the environment.

Cons: Typically lower in protein potency and often not complete on its own. Plant-based protein supplements have not been studied as well.

What to watch out for in protein powders:

All added sugars.

While there are too many different types of sugar to name, a good rule of thumb is if it ends in "-ose" or "syrup" it’s a sugar. For example, lactose, sucrose, galactose, fructose, maltose, brown rice syrup, maple syrup, etc. Other sugars may be found as cane sugar, beet sugar, brown sugar, honey, agave, etc.

Sugar alcohols.

While usually OK in small amounts, too much can cause GI disrupt. These are names that end in "-ol," like sorbitol.

Artificial sugars.

Common names include sucralose, saccharin, Splenda, aspartame, Equal, etc. These can not only cause GI distress and headaches but can actually lead to depression and weight gain as well.

Organic vs. nonorganic.

If choosing an animal source, I would make sure to opt for organic to stay away from hormones and antibiotics that may have been given to the livestock. For plant-based protein, it’s less essential as it can greatly affect the price.

What a day looks like in an ideal protein diet.

I like to wake up, work out, and grab a smoothie made with greens, banana, and plant-based protein. My favorite blend is vanilla and is a blend of quinoa, hemp, and pea. For lunch, I’m likely to grab a salad and include a protein, which is usually chickpeas, edamame, or lentils. Dinner is usually cooked greens, a whole grain like quinoa, plus about 4 ounces of wild-caught salmon. I recommend varying your proteins and having a little at each meal to ensure you're getting the perfect balance. For clients, my recommendations are really based on their preferences. I personally like to keep my animal protein to one source a day and generally prefer it in the evening. But I’m often recommending eggs in the morning and animal protein during the day. Each person is so different depending on their workout regimen and metabolism that each meal structure (a nonspecific guide of eating) that I create is based upon what an individual is already doing, with modifications and additions.

Getting protein throughout the day is essential. Making sure there is usually one source of protein at each meal (with carbohydrates and fat) can ensure that you are taking in enough of what your body needs without placing any stress on the kidneys at one time. In other words, it’s not necessary to get all of your daily protein at one time and may not be beneficial either. Additionally, it helps with satiety, stabilizing blood sugar, and is associated with weight maintenance as well. Varying the different types is essential in consuming all the essential amino acids, so make sure to switch up the sources throughout the day or even throughout the week. Be smart, read labels, and get to know what your body wants.

Lisa Hayim author page.
Lisa Hayim
Registered Dietitian

Lisa Hayim, M.S. R.D. is a wellness enthusiast based in New York, NY. She received her master's in nutrition and exercise physiology from Columbia University in 2014 and started her private practice, The Well Necessities, a few short months after.

The Well Necessities (both the practice at the website) provides readers and clients with the tools to nourish from the inside while radiating from the outside. Lisa believes that the key to health and happiness is to mindfully eat real food. When Hayim is not seeing clients or working on her website, she is doing hot yoga, trying out new restaurants, or baking healthy cookies.