What Happens to Your Body When You Don't Eat Enough Protein Every Day

Table of ContentsView AllTable of ContentsSignsRisk FactorsHow to Get More ProteinAverage Protein NeedsWhen to See a Provider

Table of ContentsView All

View All

Table of Contents

Signs

Risk Factors

How to Get More Protein

Average Protein Needs

When to See a Provider

Protein deficiency indicates a lack of protein in the body. It is a rare problem in developed countries like the United States, where there are sufficient food sources. Most of the U.S. population meets or exceeds the minimal advised recommendations for protein intake.

That said, specific populations, like older adults or maltreated children, are at risk for protein deficiency due to poor protein access or intake. Other at-risk people include those with underlying diseases associated with impaired protein absorption or metabolism.

Protein serves many vital roles, including forming muscles, bones, skin, hair, and nails. It also helps regulate the immune system and aids brain functioning. As a result, protein deficiency may lead to many symptoms, such as brittle hair and nails, mood changes, muscle weakness, and getting sick more often.

1. Weakness and Fatigue

Proteinis a crucial energy source, so when lacking, a person can feel weak and unusually exhausted—mentally, physically, or both.

This weakness and fatigue can then lead to a poorer quality of life and a poor perception of physical abilities.

Muscle wasting (cachexia) from low protein levels occurs in protein (and calorie) deficiency cases, like starvation or prolonged fasting.

2. Skin, Hair, and Nail Problems

Dry, thin hair and brittle, poorly growing nails can be the first signs of low protein levels in the body.

With more severe protein deficiency, a person’s hair loses its pigment, and curly hair becomes straight. Also, the skin can become fragile and peel and flake off.

Lastly, witheating disorderslikeanorexiaorbulimia nervosa, soft, light hair may grow on the face and body.

3. Mood Changes

Amino acids—the building blocks of proteins—are essential for producing mood-regulatingneurotransmitters(brain chemicals) likeserotoninandnorepinephrine.

Protein deficiency can lead to a reduction in these neurotransmitters, potentially contributing to the development of mood disorders, such as depression.

Depressionis a common yet serious mental health disorder that can be mild or severe.

Possible symptoms include:

Seek Emergency AttentionIf you have thoughts of suicide, dial988to reach the988 Suicide & Crisis Lifelineand speak with a trained counselor. If you or a loved one are in immediate danger, call911.

Seek Emergency Attention

If you have thoughts of suicide, dial988to reach the988 Suicide & Crisis Lifelineand speak with a trained counselor. If you or a loved one are in immediate danger, call911.

Besides depressive symptoms,anxietyhas also been linked to protein deficiency, especially in teenagers.

4. Swelling

Swelling is a classic sign ofkwashiorkor, a condition of severe protein deficiency that may occur in children living in countries with limited food resources and/or staple foods that are low in protein and high in carbohydrates (e.g., rural Africa, the Caribbean, and the Pacific islands).

Kwashiorkor causeslowalbuminlevels, which leads to fluid leaking out of blood vessels into surrounding tissues.

Children with kwashiorkor appear very thin except for significantswelling (edema)that manifests predominantly in their feet, ankles, and belly.

Other symptoms of kwashiorkor include:

Swelling can also occur with a kidney disease callednephrotic syndrome, in which a person loses high albumin levels in their urine.

With nephrotic syndrome, swelling is often prominent around the eyes before moving down the body into the legs and ankles.

Other symptoms of nephrotic syndrome related to protein loss include weight gain from excessive fluid retention and an increased vulnerability to infection (discussed below).

5. Reduced Immunity

Protein deficiency impairs theimmune system, increasing a person’s chances of developing infections.

Common infections include:

Antibodies mark and bind to foreign substances (such as germs) for destruction, whereas cytokines serve as messengers, informing and signaling the immune system to launch an attack against germs.

Cytokines are also involved in wound repair. As such, besides making people more vulnerable to illness, protein deficiency is associated with slowed wound healing.

6. Bone Changes

Evidence suggests low protein intake can worsen the natural age-related decline in bone mineral density (BMD), a measurement of bone strength.

What Is Bone Mineral Density?Bone mineral densityis the amount of calcium and other minerals in bones. The more minerals in bones, the stronger they are, and the less likely they are to break (fracture).

What Is Bone Mineral Density?

Bone mineral densityis the amount of calcium and other minerals in bones. The more minerals in bones, the stronger they are, and the less likely they are to break (fracture).

When BMD becomes too low,osteoporosiscan develop. With osteoporosis, bones are weak, brittle, and prone to break as bone mass and bone mineral density decline.

In addition to advancing age and diets low in protein, other risk factors for osteoporosis include low calcium and vitamin D intake, hormone changes, a sedentary lifestyle, and certain health conditions (e.g.,rheumatoid arthritis).

8 Foods to Support Your Bone Health

7. Stunted Growth in Children

Stunted growth is defined when a child’s height falls within the lower 2.5% of the median height of children of his or her same age.

Stunted growth is seen withkwashiorkorand another type of childhood malnutrition calledmarasmus.

Marasmusis a protein and calorie deficiency condition that can occur in babies and young children, nearly always in countries with extremely limited food resources. The prolonged lack of calorie and protein intake leads to severe weight loss and stunted growth.

Children with marasmus experience significant muscle wasting and loss of their fat stores. In addition to a very gaunt appearance, other symptoms include:

In 2022, a little over 148 million children under age 5 who were mainly from low-income nations were determined to be too short for their age.

Experts believe that not getting the nine essential amino acids in protein can disrupt the metabolic processes involved in growing tall.

Malnutrition: What You Need to Know

8. Fatty Liver

Theliveris the biggest internal organ, weighing around 4 pounds. It’s located below the lungs on the upper right side of the abdomen.The liver serves several vital functions, such as filtering blood, converting food into energy, eliminating wastes, and producing various substances likebile, proteins, andcholesterol.

When a person has afatty liver, fats calledtriglyceridesabnormally accumulate inside liver cells, enlarging the liver.

Many causes of fatty liver exist, such as high alcohol consumption and obesity. Protein deficiency is another contributor, albeit less common.

Fatty liver from protein deficiency develops when a person’s liver cannot produce unique proteins (lipoproteins) needed to help carry triglycerides out of the liver.

Symptoms of fatty liver are usually absent but, if present, include mild stomach discomfort or fatigue.

9. Weight Loss or Gain

The body’s first response to severe protein deficiency is to lower its metabolic rate and break down fat tissue as an energy supply.

The loss of fat, muscle, and organ weight causes significant weight loss. Starvation, in which there is a lack of protein and all other nutrients (e.g., during a famine), can cause weight loss of 50% or more in children.

Weight gain from protein deficiency is seen with nephrotic syndrome (discussed above) due to fluid retention.

Limited scientific data suggest that weight gain may occur in individuals with a reduced (not deficient) protein diet due to increased hunger.

Common Risk Factors of Protein Deficiency

Protein deficiency is rare in the United States. However, it can occur from a lack of access to food or in people with health conditions that affect the absorption or metabolism of protein.

Older adults, especially those withdementia(conditions affecting cognitive abilities such as memory and thinking), are vulnerable to inadequate nutritional intake, including protein.

With dementia, a person may forget to drink or have difficulties communicating hunger to caregivers. They may also have physical problems like difficulty swallowing and psychological issues that decrease their appetite, like depression or apathy.

Children suffering from neglect and abuse are also at risk.

Poor nutritional intake may also occur as a result ofalcohol use disorderor eating disorders like anorexia nervosa.

Health problems that can cause protein deficiency as a secondary consequence include:

What Does Protein Do? A Guide to This Essential Nutrient

Aim to incorporate protein into each meal and snack to ensure your body gets the essential amino acids it requires.

Two types of dietary protein are:

Most animal protein sources are “complete” because they contain all nine essential amino acids in the amounts the body needs. Only some plant-based proteins are “complete,” such as buckwheat, hempseed, quinoa, and soy.

What Foods Are High in Protein?

Evidence suggests that about 75% of Americans meet or exceed the protein intake recommendation for meats, poultry, and eggs. However, almost 90% do not meet the recommendation for seafood, and more than 50% do not for nuts, seeds, and soy products.

For an average adult consuming 2,000 calories per day, the recommended ounces of protein foods that should be eaten per week include:

For children and adolescents aged 2 and over, the recommended ounces of protein foods they should eat weekly depend on their daily calorie needs.Calorie needsare based on age, height, weight, sex, and physical activity level.

As an example, for a 6-year-old child whose calorie needs is 1,400 calories per day, the weekly recommended protein ounces include:

Discover How Much Protein You Should Be Eating Daily Based on Your Age and Sex

When to Contact a Healthcare Provider

If you are worried you are experiencing symptoms or signs of protein deficiency or are concerned about the amount of protein in your daily eating patterns, contact your primary healthcare provider.

Along with the guidance of a primary care provider, consider seeing aregistered dietitian nutritionist (RDN). An RDN can help you create an eating plan that ensures sufficient protein intake and considers your food tastes and meal routine.

32 High-Protein Snacks That Are Healthy and Portable

Summary

Protein deficiency is rare in the United States, as most Americans meet or exceed the minimal advised dietary protein recommendations.

However, when protein deficiency does occur, symptoms and signs like muscle weakness, increased infections, mood changes, and brittle hair and nails can manifest.

This is because proteins play several crucial roles in the body, including providing energy, helping the brain and immune system function, and serving as building blocks for muscle, bone, skin, hair, and nails.

Older adults, maltreated children, and those with health problems associated with impaired protein intake, absorption, or metabolism are at risk for developing protein deficiency.

Speak with your healthcare provider if you are concerned about your or your child’s protein intake. The recommended protein intake depends on age, gender, activity level, height, and weight.

The recommended dietary allowance (RDA) for protein for the average adult is 0.36 grams per pound.This is equivalent to 54 grams of protein per day for an adult weighing 150 pounds.

22 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.U.S. Department of Agriculture and U.S. Department of Health and Human Services.Dietary Guidelines for Americans, 2020-2025. 9th Edition.Bhupathiraju SN, Hu F.Protein-energy undernutrition (PEU). InMerck Manual Professional Version. Merck & Co., Inc. 2023.Neto AWG, Boslooper-Meulenbelt K, Geelink M, et al.Protein intake, fatigue and quality of life in stable outpatient kidney transplant recipients.Nutrients. 2020;12(8):2451. doi:10.3390/nu12082451UCLA Health.Are you getting enough protein? Here’s what happens if you don’t.Wong CY, Chu DH.Cutaneous signs of nutritional disorders.Int J Womens Dermatol.2021;7(5Part A):647-652. doi:10.1016/j.ijwd.2021.09.003Stamu-O’Brien C, Shivakumar S, Messas T, Kroumpouzos G.Through the looking glass: skin signs that help diagnose eating disorders.Clin Dermatol.2023;41(1):67-74. doi:10.1016/j.clindermatol.2023.03.005Zielińska M, Łuszczki E, Dereń K.Dietary nutrient deficiencies and risk of depression (review article 2018-2023).Nutrients. 2023;15(11):2433. doi: 10.3390/nu15112433American Psychiatric Association.What is depression?National Suicide Prevention Lifeline.The lifeline and 988.Khanna P, Aeri BT.Association of quantity and quality of protein intake with depression and anxiety symptoms among adolescent boys and girls (13-15 years) studying in public schools of Delhi.J Nutr Sci Vitaminol (Tokyo). 2020;66(Supplement):S141-S148. doi:10.3177/jnsv.66.S141Trehan I, Goday PS.Malnutrition in children in resource-limited settings: clinical assessment.In: UpToDate, Li B UK, Brown N (Eds), Wolters KluwerKelepouris E.Patient education: the nephrotic syndrome (beyond the basics). In: UpToDate, Glassock RJ, (Ed), Wolters KluwerLi P, Yin YL, Li D, Kim SW, Wu G.Amino acids and immune function.Br J Nutr. 2007;98(2):237-52. doi:10.1017/S000711450769936X allowing older citationWeaver AA, Tooze JA, Cauley JA, et al.Effect of dietary protein intake on bone mineral density and fracture incidence in older adults in the health, aging, and body composition study.J Gerontol A Biol Sci Med Sci. 2021;76(12):2213-2222. doi:10.1093/gerona/glab068Rizky Maulidiana A, Sutjiati E.Low intake of essential amino acids and other risk factors of stunting among under-five children in Malang City, East Java, Indonesia.J Public Health Res. 2021;10(2):2161. doi:10.4081/jphr.2021.2161World Health Organization.Joint child malnutrition estimates.American Liver Foundation.The healthy liver.Ampong I, Watkins A, Gutierrez-Merino J, Ikwuobe J, Griffiths HR.Dietary protein insufficiency: an important consideration in fatty liver disease?Br J Nutr.2020;123(6):601-609. doi:10.1017/S0007114519003064Tholey D.Fatty liver (steatosis).InMerck Manual Consumer Version. Merck & Co., Inc. 2023Pezeshki A, Zapata RC, Singh A, Yee NJ, Chelikani PK.Low protein diets produce divergent effects on energy balance.Sci Rep. 2016;6:25145. doi:10.1038/srep25145Herke M, Fink A, Langer G, et al.Environmental and behavioural modifications for improving food and fluid intake in people with dementia.Cochrane Database Syst Rev. 2018;7(7):CD011542. doi:10.1002/14651858.CD011542.pub2Harvard Health.High-protein foods: the best protein sources to include in a healthy diet.

22 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.U.S. Department of Agriculture and U.S. Department of Health and Human Services.Dietary Guidelines for Americans, 2020-2025. 9th Edition.Bhupathiraju SN, Hu F.Protein-energy undernutrition (PEU). InMerck Manual Professional Version. Merck & Co., Inc. 2023.Neto AWG, Boslooper-Meulenbelt K, Geelink M, et al.Protein intake, fatigue and quality of life in stable outpatient kidney transplant recipients.Nutrients. 2020;12(8):2451. doi:10.3390/nu12082451UCLA Health.Are you getting enough protein? Here’s what happens if you don’t.Wong CY, Chu DH.Cutaneous signs of nutritional disorders.Int J Womens Dermatol.2021;7(5Part A):647-652. doi:10.1016/j.ijwd.2021.09.003Stamu-O’Brien C, Shivakumar S, Messas T, Kroumpouzos G.Through the looking glass: skin signs that help diagnose eating disorders.Clin Dermatol.2023;41(1):67-74. doi:10.1016/j.clindermatol.2023.03.005Zielińska M, Łuszczki E, Dereń K.Dietary nutrient deficiencies and risk of depression (review article 2018-2023).Nutrients. 2023;15(11):2433. doi: 10.3390/nu15112433American Psychiatric Association.What is depression?National Suicide Prevention Lifeline.The lifeline and 988.Khanna P, Aeri BT.Association of quantity and quality of protein intake with depression and anxiety symptoms among adolescent boys and girls (13-15 years) studying in public schools of Delhi.J Nutr Sci Vitaminol (Tokyo). 2020;66(Supplement):S141-S148. doi:10.3177/jnsv.66.S141Trehan I, Goday PS.Malnutrition in children in resource-limited settings: clinical assessment.In: UpToDate, Li B UK, Brown N (Eds), Wolters KluwerKelepouris E.Patient education: the nephrotic syndrome (beyond the basics). In: UpToDate, Glassock RJ, (Ed), Wolters KluwerLi P, Yin YL, Li D, Kim SW, Wu G.Amino acids and immune function.Br J Nutr. 2007;98(2):237-52. doi:10.1017/S000711450769936X allowing older citationWeaver AA, Tooze JA, Cauley JA, et al.Effect of dietary protein intake on bone mineral density and fracture incidence in older adults in the health, aging, and body composition study.J Gerontol A Biol Sci Med Sci. 2021;76(12):2213-2222. doi:10.1093/gerona/glab068Rizky Maulidiana A, Sutjiati E.Low intake of essential amino acids and other risk factors of stunting among under-five children in Malang City, East Java, Indonesia.J Public Health Res. 2021;10(2):2161. doi:10.4081/jphr.2021.2161World Health Organization.Joint child malnutrition estimates.American Liver Foundation.The healthy liver.Ampong I, Watkins A, Gutierrez-Merino J, Ikwuobe J, Griffiths HR.Dietary protein insufficiency: an important consideration in fatty liver disease?Br J Nutr.2020;123(6):601-609. doi:10.1017/S0007114519003064Tholey D.Fatty liver (steatosis).InMerck Manual Consumer Version. Merck & Co., Inc. 2023Pezeshki A, Zapata RC, Singh A, Yee NJ, Chelikani PK.Low protein diets produce divergent effects on energy balance.Sci Rep. 2016;6:25145. doi:10.1038/srep25145Herke M, Fink A, Langer G, et al.Environmental and behavioural modifications for improving food and fluid intake in people with dementia.Cochrane Database Syst Rev. 2018;7(7):CD011542. doi:10.1002/14651858.CD011542.pub2Harvard Health.High-protein foods: the best protein sources to include in a healthy diet.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

U.S. Department of Agriculture and U.S. Department of Health and Human Services.Dietary Guidelines for Americans, 2020-2025. 9th Edition.Bhupathiraju SN, Hu F.Protein-energy undernutrition (PEU). InMerck Manual Professional Version. Merck & Co., Inc. 2023.Neto AWG, Boslooper-Meulenbelt K, Geelink M, et al.Protein intake, fatigue and quality of life in stable outpatient kidney transplant recipients.Nutrients. 2020;12(8):2451. doi:10.3390/nu12082451UCLA Health.Are you getting enough protein? Here’s what happens if you don’t.Wong CY, Chu DH.Cutaneous signs of nutritional disorders.Int J Womens Dermatol.2021;7(5Part A):647-652. doi:10.1016/j.ijwd.2021.09.003Stamu-O’Brien C, Shivakumar S, Messas T, Kroumpouzos G.Through the looking glass: skin signs that help diagnose eating disorders.Clin Dermatol.2023;41(1):67-74. doi:10.1016/j.clindermatol.2023.03.005Zielińska M, Łuszczki E, Dereń K.Dietary nutrient deficiencies and risk of depression (review article 2018-2023).Nutrients. 2023;15(11):2433. doi: 10.3390/nu15112433American Psychiatric Association.What is depression?National Suicide Prevention Lifeline.The lifeline and 988.Khanna P, Aeri BT.Association of quantity and quality of protein intake with depression and anxiety symptoms among adolescent boys and girls (13-15 years) studying in public schools of Delhi.J Nutr Sci Vitaminol (Tokyo). 2020;66(Supplement):S141-S148. doi:10.3177/jnsv.66.S141Trehan I, Goday PS.Malnutrition in children in resource-limited settings: clinical assessment.In: UpToDate, Li B UK, Brown N (Eds), Wolters KluwerKelepouris E.Patient education: the nephrotic syndrome (beyond the basics). In: UpToDate, Glassock RJ, (Ed), Wolters KluwerLi P, Yin YL, Li D, Kim SW, Wu G.Amino acids and immune function.Br J Nutr. 2007;98(2):237-52. doi:10.1017/S000711450769936X allowing older citationWeaver AA, Tooze JA, Cauley JA, et al.Effect of dietary protein intake on bone mineral density and fracture incidence in older adults in the health, aging, and body composition study.J Gerontol A Biol Sci Med Sci. 2021;76(12):2213-2222. doi:10.1093/gerona/glab068Rizky Maulidiana A, Sutjiati E.Low intake of essential amino acids and other risk factors of stunting among under-five children in Malang City, East Java, Indonesia.J Public Health Res. 2021;10(2):2161. doi:10.4081/jphr.2021.2161World Health Organization.Joint child malnutrition estimates.American Liver Foundation.The healthy liver.Ampong I, Watkins A, Gutierrez-Merino J, Ikwuobe J, Griffiths HR.Dietary protein insufficiency: an important consideration in fatty liver disease?Br J Nutr.2020;123(6):601-609. doi:10.1017/S0007114519003064Tholey D.Fatty liver (steatosis).InMerck Manual Consumer Version. Merck & Co., Inc. 2023Pezeshki A, Zapata RC, Singh A, Yee NJ, Chelikani PK.Low protein diets produce divergent effects on energy balance.Sci Rep. 2016;6:25145. doi:10.1038/srep25145Herke M, Fink A, Langer G, et al.Environmental and behavioural modifications for improving food and fluid intake in people with dementia.Cochrane Database Syst Rev. 2018;7(7):CD011542. doi:10.1002/14651858.CD011542.pub2Harvard Health.High-protein foods: the best protein sources to include in a healthy diet.

U.S. Department of Agriculture and U.S. Department of Health and Human Services.Dietary Guidelines for Americans, 2020-2025. 9th Edition.

Bhupathiraju SN, Hu F.Protein-energy undernutrition (PEU). InMerck Manual Professional Version. Merck & Co., Inc. 2023.

Neto AWG, Boslooper-Meulenbelt K, Geelink M, et al.Protein intake, fatigue and quality of life in stable outpatient kidney transplant recipients.Nutrients. 2020;12(8):2451. doi:10.3390/nu12082451

UCLA Health.Are you getting enough protein? Here’s what happens if you don’t.

Wong CY, Chu DH.Cutaneous signs of nutritional disorders.Int J Womens Dermatol.2021;7(5Part A):647-652. doi:10.1016/j.ijwd.2021.09.003

Stamu-O’Brien C, Shivakumar S, Messas T, Kroumpouzos G.Through the looking glass: skin signs that help diagnose eating disorders.Clin Dermatol.2023;41(1):67-74. doi:10.1016/j.clindermatol.2023.03.005

Zielińska M, Łuszczki E, Dereń K.Dietary nutrient deficiencies and risk of depression (review article 2018-2023).Nutrients. 2023;15(11):2433. doi: 10.3390/nu15112433

American Psychiatric Association.What is depression?

National Suicide Prevention Lifeline.The lifeline and 988.

Khanna P, Aeri BT.Association of quantity and quality of protein intake with depression and anxiety symptoms among adolescent boys and girls (13-15 years) studying in public schools of Delhi.J Nutr Sci Vitaminol (Tokyo). 2020;66(Supplement):S141-S148. doi:10.3177/jnsv.66.S141

Trehan I, Goday PS.Malnutrition in children in resource-limited settings: clinical assessment.In: UpToDate, Li B UK, Brown N (Eds), Wolters Kluwer

Kelepouris E.Patient education: the nephrotic syndrome (beyond the basics). In: UpToDate, Glassock RJ, (Ed), Wolters Kluwer

Li P, Yin YL, Li D, Kim SW, Wu G.Amino acids and immune function.Br J Nutr. 2007;98(2):237-52. doi:10.1017/S000711450769936X allowing older citation

Weaver AA, Tooze JA, Cauley JA, et al.Effect of dietary protein intake on bone mineral density and fracture incidence in older adults in the health, aging, and body composition study.J Gerontol A Biol Sci Med Sci. 2021;76(12):2213-2222. doi:10.1093/gerona/glab068

Rizky Maulidiana A, Sutjiati E.Low intake of essential amino acids and other risk factors of stunting among under-five children in Malang City, East Java, Indonesia.J Public Health Res. 2021;10(2):2161. doi:10.4081/jphr.2021.2161

World Health Organization.Joint child malnutrition estimates.

American Liver Foundation.The healthy liver.

Ampong I, Watkins A, Gutierrez-Merino J, Ikwuobe J, Griffiths HR.Dietary protein insufficiency: an important consideration in fatty liver disease?Br J Nutr.2020;123(6):601-609. doi:10.1017/S0007114519003064

Tholey D.Fatty liver (steatosis).InMerck Manual Consumer Version. Merck & Co., Inc. 2023

Pezeshki A, Zapata RC, Singh A, Yee NJ, Chelikani PK.Low protein diets produce divergent effects on energy balance.Sci Rep. 2016;6:25145. doi:10.1038/srep25145

Herke M, Fink A, Langer G, et al.Environmental and behavioural modifications for improving food and fluid intake in people with dementia.Cochrane Database Syst Rev. 2018;7(7):CD011542. doi:10.1002/14651858.CD011542.pub2

Harvard Health.High-protein foods: the best protein sources to include in a healthy diet.

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