7 Risks and Symptoms of Protein Deficiency

Protein deficiency occurs when your intake does not meet your body’s needs. Protein deficiency affects about one billion people globally [1]. Certain people in developed countries are likewise vulnerable. This includes people with an unbalanced diet, as well as confined elderly and hospitalised patients [2], [3]. While real protein deficiency is uncommon in the Western world, some people are consuming very little of it.

Insufficient protein intake may cause long-term changes in body composition, such as muscle loss. Kwashiorkor is the most severe form of protein deficiency. It is more common in children in developing countries where starvation and unbalanced nutrition are common. Protein deficiency can affect every aspect of physiological function. As a result, it is linked to a variety of symptoms. Some of these symptoms may appear even when protein deficiency is mild.

Protein deficiency happens when your intake falls short of your body’s needs. Low protein intake may cause long-term changes in body composition, such as muscle loss. The most severe form of protein deficiency is kwashiorkor. It is especially common in children in developing countries where there is widespread malnutrition.

Here are 7 risks and symptoms of protein deficiency.

1. Loss of Lean Muscle Mass

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Your muscles are the greatest protein reservoir in your body. The body takes the protein from skeletal muscles to maintain more important tissue to functions. As a result, the lack of protein over time leads to muscle loss. Even mild protein deficiency can cause muscle loss in the elderly. One study in elderly men and women showed that muscle loss among those who ate low protein diet was higher [4]. Other studies show that an increased intake of protein can delay muscle degeneration that comes with old age [5].

A higher protein intake can help prevent the onset of muscle loss in old age. According to one study, a low protein diet increases the likelihood of muscle loss in aged men and women.

2. Risk of Bone Fractures

Muscle tissues are not the only thing that is affected by protein deficiency. The bones are also at risk. Not eating enough protein can weaken your bones and increase bone fracture risks [6], [7], [8]. One study found a higher intake of the protein can lower risk of hip fractures [9]. The study associate high protein diet with a reduced risk of fracture by 69%, and the highest outcomes were linked to the animal-protein sources. Another study of hip fractures in postmenopausal women found that taking 20 grams of protein supplements per day for half a year reduced bone loss by 2.3% [10].

Taking 20g of protein supplements per day for half a year prevented bone loss by 2.3% in postmenopausal women. Ingesting animal protein sources can reduce the incidence of bone fracture by 69%.

3. Stunted Growth

Protein not only helps build muscle and bone mass, but it is also important to the overall growth of the body. Protein deficiency is detrimental to children whose growing bodies need a steady supply. Stunting is the most common sign of malnutrition in childhood. Stunted growth affected about 161 million children only in 2013 [11]. Studies show a strong correlation between low intake of protein and stunt growth [12], [13]. Kwashiorkor is also the major culprit behind the stunted growth of children, which is usually caused by malnutrition [14].

Protein deficiency is dangerous for children, whose growing bodies require a consistent supply. Only in 2013, around 161 million children experienced stunted growth.

4. Skin, Hair, and Nail Problems

Protein deficiency also affects the skin, hair, and nails. In children, for example, flaky split skin and depigmented skin patches or redness are the symptoms of kwashiorkor [15], [16]. Also, hair thinning, fading hair color, hair loss, and brittle nails are also signs of protein deficiency [17], [18]. However, unless you have a serious protein deficiency, such signs would occur.

Protein deficiency can cause hair thinning, fading hair colour, hair loss, and brittle nails. Such symptoms would not develop unless you have a severe protein deficiency.

5. Edema

Edema, a swollen and puffy skin, which is usually a symptom of kwashiorkor. Scientists believe low levels of human serum albumin, the most abundant protein in the blood’s fluid portion, or blood plasma cause it [19]. One of the major function of albumin is to maintain oncotic pressure that brings fluid into the blood flow. Albumin thus avoids the accumulation of excessive amounts of fluid in tissues or other body areas. Severe protein deficiency leads to lower oncotic stress because of reduced levels of human serum albumin. As a result, water accumulates and induces swelling of tissues.

Protein deficiency can cause a fluid buildup within the abdominal cavity for the same cause. A bloated belly is a symptom of kwashiorkor.

6. Greater Calorie Intake

If your intake of protein is insufficient, your body will try to restore your protein stores by increasing your appetite and motivating you to find something to eat [20], [21]. But a protein deficiency does not trigger the appetite to eat, at least not for everyone. It can increase the appetite for sweet foods that appear to be high in protein in some people [22]. Low intake of protein can cause weight gain and obesity, a concept known as protein leverage hypothesis [23].

Not all studies support the hypothesis, but protein is satiating more than fat and carbs [24], [25]. This is part of why increased intake of protein can reduce the overall intake of calories and encourage weight loss [26], [27]. When you feel hungry all the time and have trouble monitoring your calorie intake, try to add some lean protein to each meal.

Protein deficiency can lead to weight gain and obesity. When you’re constantly hungry and having difficulties keeping track of your calorie intake, try adding extra lean protein to each meal.

7. Fatty Liver

A fatty liver or fat accumulation in liver cells is another common symptom of kwashiorkor [28]. This condition will lead to fatty liver disease if left untreated, causing inflammation, hepatic scarring, and possibly liver failure. Among obese people, fatty liver is a common condition, especially for those who drink a lot of alcohol [29], [30]. Yet, studies suggest that impaired synthesis of fat-transporting proteins, known as lipoproteins, may lead to the condition [31].

Another symptom of kwashiorkor is a fatty liver or fat accumulation in liver cells. If left untreated, this condition will develop to fatty liver disease. A deficiency in fat-transporting proteins known as lipoproteins may cause the condition.

Does Protein Deficiency Affect Immunity?

Protein deficiency can impair the immune system. Impaired immune function can increase the risk of infection [32], [33]. For example, one study in mice found that a more serious influenza infection followed a diet containing only 2% protein, compared to 18% protein diet [34]. A low intake of protein can actually increase the risk of infection. In another nine weeks study of older women found that their immune response was reduced after a low-protein diet [35].

Protein deficiency can actually raise the risk of infection.

How Much Protein Do I Need?

The recommended daily allowance for each pound of body weight is 0.4 grams (0.8 grams per kg). Scientists estimate that for most people, this should be enough. For a person weighing 165 pounds (75 kg), should take 66 grams of protein per day. For athletes, the American College of Sports Medicine advises a daily protein consumption of 0.5 to 0.6 gram per pound of body weight (1.2–1.4 gram per kg), which should be enough for muscle maintenance and training recovery [36].

However, scientists disagree on how much is sufficient. Athletes should consume 0.9 gram of protein per pound of body weight (2 grams per kg) daily [37]. Just like athletes, older people appear to have higher protein requirements. While the RDA for elderly and young adults is currently the same, research show that it is underestimated and should be increased to 0.5 to 0.7 gram per pound of body weight (1.2–1.5 grams per kg) for older people [38], [39].

For a normal person, weighing 165 pounds (75 kg) should consume 66 grams of protein per day. The recommended daily requirement for each pound of body weight is 0.4 grams (0.8 gram per kg). Athletes and older people appear to have increased protein requirements.

What Foods are High in Protein?

High-protein foods include meats, poultry, and fish, and dairy products, tofu, grains, other vegetables and fruits, eggs, legumes, nuts, and seeds. Eating a variety of protein foods will increase the intake of nutrients. Some healthy sources of protein are lean and low-fat poultry and food. For vegetarians, there are choices such as lentils, peas, beans, nuts, grains, and refined soy products.


Most of the muscles, skin, hair, bones, and blood are protein. Protein deficiency, therefore, has a wide range of symptoms. Serious protein deficiency in children can cause swelling, fatty liver, skin degeneration, increase infection severity, and stunt growth.

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