Last updated: August 4, 2020
Protein is an essential macronutrient found in a variety of animal and plant-based foods. The body needs protein to build and repair body tissues, including muscles, skin, hair, and nails. (32) Proteins also serve as building blocks for enzymes and hormones in the body. (42) Proteins are composed of amino acids. There are 22 amino acids, however, nine cannot be made by the body and must be consumed through diet. These nine are known as essential amino acids. The remaining 13 amino acids, known as non-essential, can be manufactured in the body and are not required in one’s diet. (31)
There are several signs and symptoms that may provide an indication that you’re not consuming an adequate amount of protein. Continue reading to discover some of the common causes and effects of protein deficiency, as well as recommendations for protein intake based on your age and activity level.
What is protein deficiency?
You may have a protein deficiency if you don’t consume enough protein in your diet. While uncommon in most Western countries, protein deficiency affects approximately one billion people worldwide, particularly in developing countries. (5)(47) For example, up to 30% of children in Central Africa and South Asia do not get enough protein through their diets. (47)
Consuming adequate amounts of protein is important to maintain normal body function, and failing to meet daily protein requirements for an extended period of time can lead to several health issues, including muscle loss, weakness, and impaired immune function. (46)
In severe cases, protein deficiency can lead to a condition known as kwashiorkor. Kwashiorkor is a form of protein deficiency most commonly seen in young children living in developing countries affected by famine. (38) Kwashiorkor is characterized by abdominal distension and swelling of the extremities. When left untreated, kwashiorkor can lead to severe complications, such as shock, permanent mental and physical disabilities, and death. (4)
How much protein do you need?
The Dietary Reference Intake (DRI) of protein, which outlines the minimum recommended daily intake, is 0.8 grams per kilogram of body weight. This equates to approximately 0.36 grams per pound. (46) The examples below indicate the DRI for adult women and men based on the average weight for each specified by the Centers for Disease Control and Prevention (CDC).
- An average woman weighing 170.5 pounds (77.33 kilograms): 61 grams of protein per day
- An average man weighing 197.8 pounds (89.72 kilograms): 71 grams of protein per day (11)
Protein recommendations may vary depending on weight and activity level. For active individuals, the need for protein increases. According to the Academy of Dietetics, Dietitians of Canada, and the American College of Sports Medicine, it is recommended that athletes consume between 1.2 and 2 grams of protein per kilogram of body weight per day to help maintain lean body mass and improve injury recovery. (8)(2)
Age is another factor that influences protein needs. As you age, your need for more protein increases. Research has shown that exceeding the RDA for protein after age 40 can help to preserve muscle mass and function. (27)
The Acceptable Macronutrient Distribution Range (AMDR) is another method you can use to calculate how much protein to consume. The AMDR for protein is 10 to 35% of total calories from protein. For example, someone consuming 2,000 calories per day would need to consume between 200 calories (50 grams) and 700 calories (175 grams) from protein per day. (45)
Signs of protein deficiency
Protein deficiency can manifest itself in many ways. The following are some of the more significant effects of long-term protein deficiency.
Without adequate protein intake, muscle mass can begin to deteriorate, often referred to as muscle wasting. This happens because the body tends to pull protein from the skeletal muscles when dietary protein intake is inadequate. (40)
Consuming enough protein not only protects against muscle loss but can also help you build muscle. Research shows that increasing your protein intake can increase muscle mass and strength, especially when coupled with resistance training. (9) Furthermore, getting enough protein may help slow down age-related muscle degeneration. (34)
One study described the satiety effects of a high-protein breakfast (including 35 grams) compared to a normal-protein breakfast (including 13 grams). Participants who consumed the high-protein breakfast experienced less post-meal food cravings compared to the group consuming the normal-protein meal. (22)
If you’re feeling hungry, consider adding some lean protein to your meals or snacks to curb hunger sensations. Hard-boiled eggs, lentils, plain Greek yogurt, and white-meat poultry are all great options.
Trouble falling and staying asleep may be a sign that you’re not eating enough protein. Multiple studies have linked low protein intake, defined as less than 16% of calories from protein, with difficulty falling asleep. (20)(39)
Easily fractured or broken bones
Protein is essential for building and maintaining bone density and strength. Studies have shown inadequate protein intake (less than 0.8 g/kg of body weight) has been linked to an increased risk of bone fractures. (7)
Did you know? A study on postmenopausal women found that higher animal-based protein intake was associated with a lower risk of hip fractures. (29)
Thinning hair, brittle nails, and skin problems
Your hair, nails, and skin are made up of several proteins, including keratin and collagen. (43) Although typically only seen in severe cases, protein deficiency can lead to thinning hair, dry skin, and weak nails. (21)
In extreme cases, protein deficiency may cause edema (swelling) in the abdomen, feet, hands, or legs. Experts believe that this swelling is a result of lower serum levels of the protein albumin, which is responsible for maintaining normal oncotic pressure in the vascular system and prevents fluid from accumulating in other tissues. (4)
Not consuming enough protein for long periods of time can reduce lean body mass and diminish muscle strength, resulting in weakness and fatigue. (3)(36) Inadequate protein consumption can also lead to anemia, a condition resulting from a lack of red blood cells. Red blood cells carry oxygen throughout the body and inadequate oxygen-rich blood can cause you to feel weak and fatigued. (6)(30)
When you don’t get enough protein, your body begins to lose muscle mass. A reduction in lean body mass reduces your daily resting energy expenditure (REE), resulting in a slower metabolism. (44) If you’ve noticed your digestion has become more sluggish or you’ve gained weight recently, a slower metabolism due to protein deficiency might be to blame. (17)(35)
Compromised immune system
Protein deficiency may increase your risk of infection due to reduced concentrations of plasma amino acids. Amino acids play a role in regulating immune cells, and research has demonstrated a link between low-protein diets and a weakened immune system. (26)
A lack of protein can affect your mood. Many neurotransmitters in your brain, including GABA and serotonin, are made up of amino acids. These neurotransmitters are mood regulators and low levels play a role in anxiety and depression. (13)(19) Without adequate protein intake, the synthesis of these neurotransmitters is affected, which may negatively impact your mood. (37)
Not consuming enough protein can slow down wound healing. Protein-energy malnutrition (PEM) is most commonly seen in elderly, disabled, or chronically ill patients who are also more likely to develop wounds. Consuming adequate amounts of protein is necessary for maintaining protein stores, especially in these at-risk populations, as protein stores aid in wound healing. Loss of lean body mass of more than 15% impairs wound healing and a loss of 30% or more can promote the development of localized tissue damage called pressure ulcers. (15)
Protein intake in vegans and vegetarians
Contrary to popular belief, you can get all of the protein you need from a plant-based diet – it may just require a bit more planning and effort. (1) If you follow a vegetarian or vegan diet, focus on including plant-based proteins with each meal and snack. Lentils, tofu, beans, and peas are great sources of plant-based protein. Protein can also be found in grains, nuts, and seeds, such as quinoa, hemp seeds, and almonds. If you’re following a vegetarian diet that allows the inclusion of some animal-based products, protein can also be found in eggs, cheese, milk, and yogurt. (41)
Animal proteins contain all essential amino acids, however, few plant-based protein sources do. Therefore, eating a variety of plant-based foods and pairing specific kinds of plant-based protein sources can help ensure you’re getting enough of each essential amino acid in your diet. (28)
Most people can meet their protein requirements through diet alone. However, if you struggle with consuming enough protein throughout the day or if you’re especially active, protein supplements may be beneficial. (10)(24)(12) Protein supplements typically come in powder form and are available in a variety of flavors. Today’s protein powders are also able to suit many different dietary needs, such as plant-based, paleo, or ketogenic diets.
The bottom line
True protein deficiency is uncommon in developed countries. However, low protein intake over time may lead to some of the protein deficiency symptoms discussed above. If you experience any of these signs or are concerned about not getting enough protein in your diet, consult your integrative healthcare practitioner for recommendations specific to your needs and health goals.
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