How to tell if you're not getting enough protein?

October 20, 2025 •

5 min read

Protein is the most abundant molecule in the body after water, acting as a crucial building block for every cell. Here's how to tell if you're not getting enough protein by recognizing the subtle and obvious signs your body might be giving you.

Quick Summary

Insufficient protein manifests through symptoms such as muscle weakness, persistent fatigue, brittle hair and nails, and swelling (edema). The body may also signal its need with increased hunger, brain fog, and a weakened immune system.

Key Points

Know the physical signs: Watch for muscle weakness, wasting, and persistent fatigue, which can indicate your body is breaking down its own muscle tissue for energy.
Check your appearance: Brittle nails, thinning hair, or dry, flaky skin can be outward indicators of insufficient protein.
Monitor your cravings: Unexplained, constant hunger and a craving for sugary carbs may signal that your body is not getting enough satiating protein.
Watch for swelling: Edema, or swelling in your feet, ankles, or abdomen, can be caused by low levels of the blood protein albumin.
Assess your immunity: Frequent infections or wounds that heal slowly may point to a weakened immune system due to a lack of protein for antibody production.
Heed mental changes: Brain fog, mood swings, or irritability can be linked to protein's role in creating vital neurotransmitters.
Identify risk factors: Older adults, athletes, vegans, and those with certain chronic illnesses face a higher risk of deficiency.

The Vital Role of Protein in Your Body

Protein is more than just a macronutrient for bodybuilders; it is a fundamental component for virtually every function in your body. Made up of amino acids, proteins are constantly being broken down and rebuilt for essential processes. When your dietary intake is insufficient, your body begins to cannibalize its own resources, starting with muscle tissue, to prioritize the most critical bodily functions. Understanding these roles helps illustrate why a deficiency has such widespread effects.

Tissue Maintenance and Repair: Proteins are vital for repairing and building new tissues throughout the body, including skin, bone, and muscle. This process is especially crucial after physical activity, injury, or surgery.
Enzymes and Hormones: Many enzymes that speed up chemical reactions, and hormones that act as chemical messengers (like insulin), are made of protein. A protein deficiency can disrupt these essential regulatory functions.
Immune Function: Antibodies, which fight off infections, are proteins. A low protein intake impairs the immune system, making you more susceptible to illnesses and infections.
Fluid Balance: Proteins, particularly albumin, circulate in the blood and help maintain the body's fluid balance. Low levels can lead to fluid leaking into tissues, causing swelling or edema.
Energy Source: While not the primary energy source, the body will break down protein for energy during periods of calorie restriction.

Key Signs You Need More Protein

If your body's protein reserves are low, it will send out multiple warning signals. Recognizing these can help you act early to prevent more serious health issues.

Muscle Loss and Weakness

One of the most noticeable signs of inadequate protein is a decline in muscle mass and strength. Since nearly half of the body's protein is stored in muscles, your body will draw from this reserve when protein intake is low. This can manifest as:

Weakness during everyday tasks or exercise.
A noticeable decrease in muscle size over time.
Increased risk of falls, especially in older adults.

Fatigue and Brain Fog

Feelings of persistent tiredness, weakness, and an inability to concentrate can be linked to low protein. Amino acids, the building blocks of protein, are necessary for creating neurotransmitters like dopamine and serotonin that regulate mood and brain function. A deficiency can lead to:

Reduced energy levels and stamina.
Difficulty focusing or memory issues.
Increased irritability or mood swings.

Brittle Hair, Nails, and Skin Issues

Keratin, collagen, and elastin are structural proteins that provide strength and elasticity to your hair, skin, and nails. When protein is scarce, the body prioritizes more vital organs, leaving hair and nails brittle and skin dry and flaky. You might see:

Thinning hair or increased hair shedding.
Weak, brittle nails or deep ridges in your fingernails.
Dry, flaky, or rash-prone skin.

Edema (Swelling)

Protein plays a critical role in maintaining fluid balance within the body. Low levels of the blood protein albumin can cause fluid to accumulate in tissues, leading to swelling, or edema. This is most often seen in the feet, ankles, and legs, and sometimes the abdomen.

Slow Wound Healing and Weakened Immunity

Protein is necessary for repairing tissue and creating antibodies that fight infection. A deficiency can lead to:

Cuts, scrapes, or bruises that take longer than usual to heal.
Getting sick more frequently due to a weakened immune system.

Increased Hunger and Cravings

Protein promotes satiety and helps stabilize blood sugar levels. If you feel hungry shortly after eating a meal, or constantly crave carbs and sugary foods, your body might be signaling a need for more protein. This can also be a factor in weight gain, as muscle loss slows your metabolism.

What to Do If You Suspect a Deficiency

Assess Your Diet: Review your typical meals to see if they consistently include a protein source. The Recommended Dietary Allowance (RDA) is a minimum of 0.8 grams per kilogram of body weight, but this can increase based on activity level, age, and health status. Use the USDA's MyPlate Plan Calculator to estimate your personal needs.
Add Protein to Every Meal: Aim to include a protein source in each meal and snack to ensure a steady supply of amino acids. Starting your day with protein, such as eggs or Greek yogurt, can boost satiety.
Incorporate Varied Sources: Ensure a mix of both animal and plant-based protein sources throughout the day. Animal proteins (meat, fish, eggs, dairy) are 'complete,' containing all essential amino acids, while plant proteins (beans, nuts, whole grains) should be varied to achieve a full profile.
Consider Supplements (if needed): Protein powders and shakes can be a convenient way to boost intake, especially for active individuals, older adults, or those with a reduced appetite. Always consult with a healthcare professional before starting supplements.
Consult a Healthcare Provider: Since many symptoms of protein deficiency overlap with other conditions, it is crucial to consult a doctor or registered dietitian for an accurate diagnosis, especially if you experience persistent symptoms. A blood test can help determine your protein levels.

Comparison of Protein Deficiency vs. General Malaise


Symptom	Protein Deficiency	General Malaise (Common causes)
Fatigue	Persistent and often accompanied by muscle weakness and brain fog.	Can be caused by sleep deprivation, stress, other nutritional deficiencies (e.g., iron), or overexertion.
Muscle Weakness	Directly tied to the body breaking down muscle tissue for energy.	Can result from a lack of exercise, illness, or general aging, but is typically not accompanied by muscle wasting.
Mood Swings	Linked to insufficient production of neurotransmitters like serotonin and dopamine.	Can be caused by stress, hormonal changes, or other mental health factors.
Swelling (Edema)	Caused by low levels of the blood protein albumin, leading to fluid accumulation.	Many other causes, including heart or kidney issues, pregnancy, and prolonged sitting. Medical consultation is necessary.
Hair/Nail Changes	Hair becomes brittle, thin, or falls out, and nails weaken or develop ridges as protein is diverted away from 'non-essential' parts.	Can also be due to hormonal changes, underlying medical conditions, or specific vitamin deficiencies.

Who Is At a Higher Risk of Protein Deficiency?

While most people in developed countries get enough protein, certain groups are at a higher risk of inadequate intake:

Older Adults: Appetite reduction, changes in taste, and age-related muscle loss (sarcopenia) increase protein needs while often decreasing intake.
Vegetarians and Vegans: Without proper planning, plant-based diets can lack sufficient or complete protein sources. A varied intake of legumes, nuts, seeds, and soy is key.
Athletes: Individuals with high training demands need significantly more protein to support muscle repair and growth.
People with Chronic Illnesses: Conditions affecting nutrient absorption (like Crohn's disease or celiac disease) or increasing protein requirements (like cancer, burns, or kidney disease) can lead to deficiency.
Post-Surgery Patients: Recovery and healing increase the body's demand for protein.

Conclusion

Recognizing the signs of protein deficiency is crucial for maintaining overall health. The symptoms, from fatigue and muscle weakness to hair and skin problems, are your body's way of signaling a vital need. By understanding the importance of this macronutrient and ensuring a varied, protein-rich diet, you can prevent many related health issues. For the most accurate diagnosis and personalized advice, especially if symptoms are persistent, always consult with a healthcare provider. A proactive approach to your nutrition can keep your body and mind functioning at their best. For further reading on the functions of protein, you can consult this resource from Healthline.

Frequently Asked Questions

One of the most common signs is muscle loss and weakness. The body breaks down muscle tissue to get the protein it needs, leading to a noticeable decline in physical strength and stamina.

Yes, protein deficiency can cause hair loss, thinning, and hair breakage. It can also lead to brittle or weak nails. This happens because hair and nails are made of proteins like keratin, and the body diverts protein to more critical functions when intake is low.

Yes, a lack of protein can cause swelling, a condition known as edema. This is because proteins like albumin help maintain fluid balance in the blood, and low levels allow fluid to leak into surrounding tissues, particularly in the lower legs and feet.

Protein is a source of energy and helps promote satiety. Without enough protein, your energy levels can drop, and your body will signal for more fuel, leading to persistent hunger and cravings for carbs.

Older adults, strict vegetarians and vegans, individuals with certain chronic illnesses (e.g., kidney or liver disease), and people recovering from surgery or injury are at a higher risk of protein deficiency.

If you suspect a protein deficiency, a healthcare provider can order a blood test to check your overall protein and albumin levels. It is important to consult a doctor for a proper diagnosis.

Excellent sources of protein include lean meats, fish, eggs, dairy products (like Greek yogurt and cottage cheese), legumes (beans, lentils), nuts, seeds, and soy products (tofu, tempeh).

Yes, it is possible to get enough protein on a plant-based diet by consuming a wide variety of protein sources throughout the day. Combining foods like rice and beans can provide all the essential amino acids.

You can increase protein intake by adding a protein source to every meal and snack. Consider starting your day with eggs, adding nuts and seeds to yogurt or oatmeal, or choosing high-protein snacks like Greek yogurt or cottage cheese.