It is safe to say that protein is one of the most important nutrients. Protein is the building block of your muscles, skin, enzymes, tissues, and hormones. Most foods (even those that are not protein dominant) contain some of the protein in them, which is why true protein deficiency is rare in developed countries. However, some people may still be at risk. Deficiency leads to many health problems, and low protein intake can make subtle changes in your body over time.

What is Protein Deficiency

Protein deficiency is when people do not get adequate amounts of protein from their diet. An estimated one billion people worldwide suffer from inadequate protein intake. Too little protein may cause changes in body composition that develop over a long period of time, such as muscle wasting. The most severe form of protein deficiency is known as kwashiorkor. It most often occurs in children in developing countries where famine and imbalanced diets are common.

Signs of Low Protein Intake or Deficiency

  • Edema – Edema, which is characterized by swollen and puffy skin, is a classic symptom of kwashiorkor. Scientists believe it is caused by low amounts of human serum albumin, which is the most abundant protein in the liquid part of blood, or blood plasma. One of albumin’s main functions is to maintain oncotic pressure, a force that draws fluid into the blood circulation. Because of reduced human serum albumin levels, severe protein deficiency leads to lower oncotic pressure. As a result, fluid accumulates in tissues, causing swelling. For the same reason, protein deficiency may lead to fluid buildup inside the abdominal cavity. A bloated stomach is a characteristic sign of kwashiorkor. Remember, edema is a symptom of severe protein deficiency.
  • Fatty Liver – Another common symptom is a fatty liver or fat accumulation in liver cells. Left untreated, the condition may develop into fatty liver disease, causing inflammation, liver scarring and potentially liver failure. Fatty liver is a common condition in obese people, as well as those who consume a lot of alcohol. Why it occurs in cases of protein deficiency is unclear, but studies suggest that an impaired synthesis of fat-transporting proteins, known as lipoproteins, may contribute to the condition.
  • Loss of Muscle Mass – Your muscles are your body’s largest reservoir of protein. When dietary protein is in short supply, the body tends to take protein from skeletal muscles to preserve more important tissues and body functions. As a result, lack of protein leads to muscle wasting over time. Even moderate protein insufficiency may cause muscle wasting, especially in elderly people.
  • Risk of Bone Fractures – Muscles are not the only tissues affected by low protein intake. Your bones are also at risk. Protein helps maintain the strength and density of bones. Insufficient protein intake has been linked to a lower bone mineral density and an increased risk of fractures.
  • Hair, Skin, and Nail Problems – Protein deficiency often leaves its mark on the hair, skin, and nails, which are largely made of protein. Severe protein deficiency may affect your skin, causing redness, flaky skin, and depigmentation. It may also cause brittle nails and hair loss.
  • Increased Severity of Infections – Eating too little protein may impair your body’s ability to fight infections, such as the common cold. Because protein deficiency takes its toll on the immune system.
  • Increased Appetite and Calorie Intake – Although poor appetite is one of the symptoms of severe protein deficiency, the opposite seems to be true for milder forms of deficiency. When your protein intake is inadequate, your body attempts to restore your protein status by increasing your appetite, encouraging you to find something to eat. As a result, poor protein intake may lead to weight gain and obesity, an idea known as the protein leverage hypothesis. Not all studies support the hypothesis, but it has been proven that protein is more satiating than carbs and fat. This is part of the reason why increased protein intake can reduce overall calorie intake and promote weight loss.
  • Stunt Growth in Children – Insufficient protein intake may delay or prevent growth in children. Protein not only helps maintain muscle and bone mass, but it’s also essential for body growth.

Not everyone has the same protein requirements. It depends on many factors, including body weight, muscle mass, physical activity, and age. Bodyweight is the most important determinant of protein requirements. As a result, recommendations are usually presented as grams for each pound or kilogram of body weight. Again, if you are an athlete (or regularly exercise especially weight lifting) or are older your daily protein intake should be significantly higher than the average sedentary persons.

For optimal health, make sure to include protein-rich foods in every meal. The highest sources of protein include meat, fish, eggs, dairy products, and legumes.


Serious protein deficiency can cause swelling, fatty liver, skin degeneration, increase the severity of infections and stunt growth in children. While true deficiency is rare in developed countries, low intake may cause muscle wasting and increase the risk of bone fractures. Some evidence even suggests that getting too little protein may increase appetite and promote overeating and obesity.