The Truth About Protein: Needs, Myths, and What to Tell Your Patients

This article was written and submitted by Dietetic Intern, Christine Beckel. Reviewed by Colleen Sloan

Protein is the macronutrient largely associated with muscle growth and maintenance, and rightly so. There is no denying that amino acids (the end products of protein digestion) are the building blocks for muscle. However, we tend to forget that they are also the building blocks for just about everything else.

In fact, it is estimated that less than 20% of the protein we ingest is incorporated into muscle mass, even following resistance training. The remaining 80+ percent goes to other uses, including formation of all enzymes, many neurotransmitters and hormones, immune antibodies, various components of blood, bone, hair, organs, skin, nails… the list goes on. Because of this, adequate protein intake is essential for most daily functions of the human body.

Insufficient protein intake is associated not only with muscle loss, but also depressed immune function, stunted growth, fluid shifts in the interstitial tissues (presenting as edema of the abdomen or lower extremities), decreased bone density, mood swings and “brain fog,” fatigue, issues with hair, skin, or nails and, in extreme cases, organ damage or failure.

Doesn’t sound great, does it? But before we panic and push protein supplements on every patient to walk into our clinic, let’s take a look at the prevalence of protein insufficiency.

The good news is that, within developed countries such as the US, true protein deficiency is virtually unheard of amongst the general population, except in cases of overall malnourishment and certain disease states such as cachexia. While patients following poor dietary habits may have mild symptoms from low-protein status, adequate protein status is easily achieved with any balanced diet (meaning a diet that obtains about 10-35% of its calories from protein sources, the Acceptable Macronutrient Distribution Range for protein according to the Food and Nutrition Board (FNB) of the National Academies of Sciences, Engineering, and Medicine).

Though certain sources are better than others, protein is largely ubiquitous in foods (even fruits and vegetables contain small amounts), and the RDA is easily achievable on most diets, even when not particularly healthy or balanced. True protein deficiency is generally only seen in the cases of extreme calorie restriction, starvation, and disease states involving hypermetabolism and/or impaired nutrient intake or utilization.

So how much protein does the average healthy person need to eat daily to avoid the deficiency symptoms described above?

The RDA (recommended dietary allowance) for protein set by the FNB is only 0.8 grams protein per kilogram of body weight, or about 54 g/d of protein for a 150lb person. This is considered the amount “sufficient” to meet the needs of the majority of the American adult population, meaning it represents the lower end of the acceptable range.

Because many benefits (most notably: increased satiety, enhanced blood glucose control, improved skeletal muscle maintenance, and weight management) have been associated with a higher intake of protein, most nutrition experts recommend between 1.2-1.6 g/kg/d for the average individual.

To simplify things for your patients who may not like crunching the numbers (or any patients you suspect may struggle with obsessing over tracking food intakes) an easy rule of thumb is to recommend patients dedicate about one quarter of their plate to a lean protein source at each meal. Some great sources to recommend? Fish, poultry, eggs, tofu, Greek yogurt, low-fat milk, beans and legumes.  

OK… so that covers the average patient. But what about special populations? If protein has so many benefits, are there patients who we should recommend eat more of it?

Absolutely. Many therapeutic diets incorporate increased protein. Protein needs are markedly higher for any patients with hypermetabolic or catabolic states such as cancer, cachexia, traumatic brain injuries, burns, premature birth, etc. (Severe cases may require over double the average protein recommendations). Increased protein intake is also essential for any patients who have tissues in need of repair, such as patients with active wounds or ulcers or who recently underwent surgery. Less dramatic increases in protein (think about 1.5 g/kg) may be helpful for prevention of sarcopenia in older adults (when paired with resistance training) or for better blood glucose control in diabetics (when consumption of protein is paired with carbohydrate intake). Finally, research shows that athletes who routinely undergo muscle breakdown and repair will also benefit from a higher intake of protein to encourage muscle maintenance and growth. The American College of Sports Medicine recommends intakes of 1.2 – 2 g/kg depending on the type, duration, and frequency of physical activity.  

So… our final thoughts on protein?

1. Protein is an essential nutrient for most functions of the human body and, consequently, protein deficiency has widespread health consequences. However, with any (at least relatively balanced) diet, adequate protein status is easily achieved. Consumption of about 0.8 g/kg/d protein is sufficient for most healthy adults.
2. Because increased intake of protein has been shown to have many benefits, it is reasonable to recommend between 1.2-1.6 g/kg/d for most healthy individuals.
3. An easy rule of thumb is to recommend patients fill about one quarter of their plate with a good source of protein at each meal.
4. Some patient populations may benefit from higher protein intakes. These patients should also work with a registered dietitian to ensure that their diet meets their specific nutrient needs.
5. Great sources of protein to recommend include lean animal products (poultry, fish, low-fat dairy products, eggs) and plant proteins (soy products, beans and legumes, nuts and seeds, whole grains).

For more information on protein intake and tips for athletes check out these podcast episodes:

• 72 | Popular Diets and Supplement Science
• 70 | Optimizing Athletic Performance
• 35 | Game ON! Nutrition Tips for Athletes

And if you're curious about how to select quality protein supplements, check out episode 63 | How to Choose a Protein Supplement

Bonus story (from Christine) for those of you who made it this far…

When my brother-in-law (a protein-shake-slugging, weight-lifting, fitness-and-nutrition-enthusiast who gets most of his information from YouTube and Instagram) informed me that a new study found that the human body can absorb 100 grams of protein per meal, I just had to fact check him. 100 grams of protein (equivalent to about 4 chicken breasts, a one-pound steak, 3 quarters of a gallon of milk, or 15 eggs) is an absurd amount to eat in one sitting. And yet, the article he was referencing, a 2023 study conducted by Trommelen et al.,  did indeed find the human body capable of absorbing such a huge quantity of protein at once.

The question remains, however, just because the body CAN absorb this much protein, does that mean the body SHOULD?

Interestingly, the same study found that, despite its ability to absorb a seemingly unlimited amount of protein, the human body benefits little from amounts of protein exceeding about 20 - 25 g at a time, at least regarding de novo muscle synthesis, even following resistance training. So, if you’re slugging down 100 grams, and your muscles are only benefiting from the first 25, what happens to the other 75? Likely, the majority of it will be used for energy (if you are Michael Phelps, burning 9000 calories a day) or fat storage (if you… aren’t exactly an Olympian athlete).

So… bottom line… Athletes benefit from increased protein intake following a workout. Yes. Absolutely. It is well established that when it comes to muscle recovery, protein is your best friend.

But just because someone on YouTube eats a whole rotisserie chicken every time they lift a dumbbell does not necessarily mean that you need to. Research shows that a post-workout meal featuring a chicken breast (yes, just the one), maybe alongside some quinoa, black beans, and veggies should be more than enough to keep you healthy and performing at your best.