Protein is a critical nutrient for all people. Without enough protein from varying sources, humans will experience a number of health problems, including:
- impaired immune function
- muscle wasting
- osteoporosis and brittle bones
- hormone abnormalities and growth disorders
- altered brain function
- brittle hair and nails
- accelerated skin aging
- impaired sleep
Many of these problems can actually contribute to stress or inability to handle stress, poor appetite control, over-eating and weight gain.
Let’s examine what happens when you don’t get enough protein.
What Does Protein Do For You?
1. Protein is an Immune-Boosting Nutrient
Your immune system uses dietary protein to make antibodies (immune cells that fight infection). Without enough protein available to make these antibodies, your immune system cannot effectively fight off invaders like flu viruses and bacterial infections (1, 2, 3, 4).
If you routinely do not consume enough protein from food sources, over time, your immune cells will decrease and your responses to infections will be weaker.
This is one of the reasons that protein supplements are used so frequently in hospitals and long-term care clinics. Patients who don’t eat enough protein are at much higher risk of developing infections while hospitalized.
2. Protein Saves Your Muscles, But Helps Burn Fat
Even if you’re not in the gym pumping the iron in pursuit of the perfect swole, muscle is still incredibly vital for all people.
Muscle is a very metabolically active tissue, which means it boost your body’s metabolic rate. This means that people with more muscle burn more calories at rest compared to individuals with less muscle (5, 6).
When you regularly do not consume enough protein, your body will use skeletal muscle as the building blocks for other critical proteins in your body (like immune cells and other structural proteins) (7).
In addition to burning more calories all the time, studies have shown that people with more muscle are at much lower risk of developing obesity, Type 2 Diabetes and other metabolic disorders (8, 9, 10, 11, 12).
Consider muscle to be your best way to combat excess body fat accumulation because it provides a warehouse for your body to store nutrients other than in fat cells.
3. Protein Builds Strong Bones
We may not initially think that protein has much to do with our bones and bone density. Our bones are mostly made of minerals like calcium on the outside. However, the inner bone matrix that provides important circulation and nutrients to bones is made of protein.
Protein in the form of mostly collagen forms the matrix inside your bones that not only nourishes the cells, but also provides a strong structural support to the bones themselves (13).
Research seems to indicate that animal-based proteins increase the amounts of insulin-like growth factor (IGF-1), which in turn increases bone mineralization and reduces bone fractures (14). Soy-based proteins actually may decrease levels of IGF-1 (15).
4. Protein Helps You Make Hormones
Proteins are the base for many of the hormones in your body.
Some of those include thyroid hormones, growth hormone, adrenal hormones, pancreatic hormones like insulin and somatostatin, oxytocin, prolactin, gut hormones such as gastrin and cholecystokinin, and leptin.
If you’re one of the many people that suffers from any of the conditions that are associated with hormone abnormalities, boosting your protein intake can often be beneficial to providing more of one of the building blocks needed to make those hormones.
Insufficient protein intake has been linked to hypothyroidism, impaired blood glucose clearance (high blood sugar), growth disorders, adrenal dysfunction, increased risk of intestinal disorders and inflammation, and increased appetite at meals (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31).
5. Protein Helps Your Brain Grow and Function
There are plenty of reasons why protein helps our bodies grow, but specifically speaking of our brains, protein is a critical nutrient in infants, developing children, and even adults.
6. Protein is What Your Hair and Nails Are Made of
Even if you feel like you’re impervious to chronic diseases like malnutrition, changes to your hair and nails can happen rapidly due to changes in your nutritional intake.
When your total available pool of body protein goes to priorities like rebuilding heart muscle, making hormones and healing wounds, your hair and nails will typically come near the end of the list of functions that require protein.
The proteins that make up your hair and nails are made of keratin. When you don’t eat enough protein, your hair becomes brittle and your nails develop cracks and break easily.
You could definitely be eating enough protein to survive and stay out of protein-energy malnutrition, but that doesn’t mean you’re eating enough protein to really feed your hair follicles and nail beds with building blocks for those things (38, 39).
7. Protein Keeps Your Skin Looking Young
The protein in your skin that helps it remain smooth, young and healthy is mostly made of collagen and other fibers like elastin. Protein is also crucial to wound-healing, so, when you’re not consuming enough overall to support all protein needs, your skin’s ability to heal damage is reduced (40, 41).
8. Protein is What Carries Iron in Your Blood
When we think of anemia, we often think of people who just don’t consume enough iron in their diet. But, dietary iron sources are only a piece of the anemia puzzle.
Iron is carried in your blood by proteins called transferrin and stored in the body on proteins called ferritin. It is very common to see clinically or sub-clinically low levels of these proteins in people who have anemia (42, 43, 44).
Even if you eat enough iron-containing foods, without enough protein stores in the body to carry or store those iron molecules, your total available iron will be low because there is nothing for it to ride along with (45).
9. Protein Helps You Sleep Better
Higher protein diets have been shown to improve sleep quality in overweight and obese adults during calorie-restricted diets (46).
Protein not only makes you feel fuller after meals, but it also appears to improve the quality and duration of your sleep. More research is needed into the specific roles that broad macronutrient categories play in the many functions of sleep, but generally, the trend seems to indicate that more protein = longer and better quality sleep (47).
The Main Point:
Eat more protein. It is an understatement to say it is a critical nutrient. It performs thousands of functions in your body and without enough of it, you just won’t feel great or experience a the highest quality of health.
Aren’t Most of These Examples of Extreme Protein Deficiency?
Hey, good for you for paying attention. Yes, many examples given are things that can happen when you’re super low on protein, for a prolonged period of time.
But, just because you might not feel you fit into some of the categories described in some of the resources (elderly, malnourished or kidney failure, etc), doesn’t mean that you might not still be in the category I call ‘sub-clinically low protein intake.’
These are people who don’t show a protein deficiency on their labwork yet, but that, after discussing their typical dietary intake, clearly aren’t eating enough protein for a number of their goals.
Let me provide some clinical observations on this, from all my years of working with varied populations.
1. Women (of all ages) tend not to eat enough protein.
This is partly because of social norms and partly because it is just not a food we emphasize, or that’s ‘trendy’ for us. We also don’t get the same hedonic pleasure from eating chicken that we do from eating cookies.
How this carries over into our health is mainly that, because we eat little protein, we aren’t very satiated at meals. This means we feel less full when we finish eating, and we’re more likely to eat more calories either at that meal, or later on after the meal.
2. The protein content of your meal often determines whether you will snack later.
This one really goes back to #1 above. The more protein you eat at meals, the more likely you are to remain full for a longer period of time after meals. I rarely encourage someone to portion-control their lean proteins for this reason.
3. People who constantly diet are focused on starving their fat away, rather than burning it away through muscle.
You all know this person. It might even be you. The chronic dieter. The I’m-doing-a-new-cleanse-this-week carpool mom. The vegan-juice-fasting co-worker. And so on.
None of these types of plans actually focus on what’s best for your metabolism long-term. They don’t encourage you to feed your lean body mass (muscle) with excellent, nutritious proteins. They just focus on limiting behaviors for a short period of time.
Feeding yourself more protein all day long keeps you full and builds muscle (provided you are doing things that will encourage muscle to grow, like running, weightlifting or other exercise), which burns more fat in the long run and tends to stay off more permanently (48).
4. Gastric bypass patients are at a lot higher risk of protein-energy malnutrition.
Once you alter the usable surface area of the stomach, you alter it’s ability to efficiently digest food. Every single thing your stomach lining cells produce serves a critical purpose.
When you either don’t make those gastric juices or don’t make enough of them, you limit your nutrient digestion and absorption, and it goes beyond just B12.
I realize for some people, a gastric bypass can be a life-saving tool to get them on the path to healing and wellness. For others, it can be a choice fraught with complications and a high rate of secondary illnesses, if they are not compliant with therapy.
If you do get one, or already have one, realize that you may need long term interventions to assist with digestion, which is not commonly discussed with these patients.
So, it’s evident we need more protein. But, how do we get more in our diet?
Sources of Protein
- Animal meat makes up the majority of proteins consumed by most people. Sources of animal meat proteins might include:
- Poultry (chicken, turkey, duck, quail)
- Game meat (elk, venison, bison, wild boar, rabbit, etc)
- Fish and shellfish
- Another source of animal-based protein is dairy. Dairy is derived from the milk of the animal and comes in several common forms, such as:
- Yogurt and kefir
- Plant proteins can also make up a good portion of the diet of most people, however, no plant proteins contain all 22 amino acids, and therefore are not considered ‘complete’ proteins. Sources of plant protein include:
- Soy and tofu products
- Some grains
- Eggs neither qualify as a meat or a dairy product, but often get lumped into either of those categories. I consider them to be a category of their own, because of their unique nutrient makeup.
- Supplements are another source of protein that many people under-utilize for several reasons. Sometimes, we aren’t sure which ones are the best. We might also fear they are unhealthy, due to news stories claiming they contain banned substances. There is also the perception that ‘too much protein’ is bad for us. Supplements commonly used might be:
- Protein powders (both animal-based and plant-based)
- Amino acid powder supplements
- Nutritional shakes/drinks
Getting a minimum of 0.8g/kg bodyweight daily is critical to preventing long-term complications from protein-energy malnutrition.
But that’s the minimum.
What if you’re active, or beginning to be active and want to boost your body’s lean mass, feel more full and optimize all the functions in your body that depend on protein?
Newer research shows that the recommended intake of protein per day to stimulate lean muscle growth and maintenance, as well as prevent insulin resistance and metabolic decline that is common as we age, is probably closer to 1.0g/kg bodyweight per day, with about 30-35 grams of protein per meal increments (51).
All boiled down, this means that the average adult should be eating a minimum of a 4 oz portion of protein at least 3 times a day. This is a protein serving slightly larger than the palm of your hand.