Who Should Not Eat High Protein Diets?

January 5, 2026 •

4 min read

According to a study published in the Journal of the American Society of Nephrology, high protein diets can cause intraglomerular hypertension, which may harm kidney function. This and other potential health concerns mean that a high-protein diet is not suitable for everyone, and it is crucial to understand who should not eat high protein to avoid serious health complications.

Quick Summary

Excessive protein intake can pose significant health risks for certain individuals, including those with pre-existing kidney or liver disease, metabolic disorders, and specific sensitivities. Long-term high protein consumption may strain organs, cause nutrient imbalances, and lead to complications like kidney stones. Prior consultation with a healthcare provider is essential to determine personal dietary needs.

Key Points

Kidney Disease: People with compromised kidney function should strictly limit high protein intake, as it significantly increases the kidneys' workload and can accelerate disease progression.
Liver Disease: Individuals with certain liver conditions, like cirrhosis, should avoid excessive protein to prevent the buildup of toxic metabolic byproducts such as ammonia.
Metabolic Disorders: Genetic conditions like Lysinuric Protein Intolerance and Phenylketonuria require careful management of protein to avoid dangerous health complications.
Digestive and Hydration Issues: High protein diets, especially those low in fiber, can cause constipation, while increased nitrogenous waste from protein metabolism can lead to dehydration.
Nutrient Imbalance: An overemphasis on protein can lead to a lack of other essential nutrients from fruits, vegetables, and whole grains, compromising overall health.
Professional Guidance is Key: Anyone with a pre-existing medical condition or health concerns should consult a doctor or dietitian before embarking on a high-protein diet.

Underlying Health Conditions Requiring Protein Restriction

For some individuals, a high-protein diet can exacerbate existing health issues rather than promote wellness. The primary concerns revolve around the body's major filtering and processing organs: the kidneys and the liver.

Kidney Disease

Perhaps the most significant group of people who should not eat high protein are those with kidney disease, also known as renal disease. The kidneys are responsible for filtering the waste products of protein metabolism from the blood. A high intake of protein increases the workload on these organs, and for individuals with already compromised kidney function, this extra strain can be damaging. Over time, this can accelerate the progression of kidney disease and may lead to a dangerous buildup of waste products in the blood. This can also be a risk for healthy individuals on certain diets, like the ketogenic diet, which can promote a more acidic urine and potentially lead to kidney stones.

Liver Conditions

The liver plays a vital role in processing amino acids from protein. For individuals with advanced liver disease, such as cirrhosis, a high protein intake can be problematic. The liver's reduced capacity can lead to the accumulation of toxic byproducts of protein metabolism, such as ammonia, in the bloodstream. This condition, known as hepatic encephalopathy, can cause neurological symptoms, including confusion and fatigue.

Inherited Metabolic Disorders

Certain rare, inherited conditions fundamentally affect the body's ability to process protein. For people with these disorders, consuming high amounts of protein can be extremely dangerous. A prime example is Lysinuric Protein Intolerance (LPI), a genetic condition where the body cannot properly transport certain amino acids. A high protein intake in individuals with LPI can lead to elevated ammonia levels, severe fatigue, and other serious health problems. Similarly, individuals with Phenylketonuria (PKU) must strictly limit their intake of the amino acid phenylalanine found in protein-rich foods.

Pregnancy and Breastfeeding

While protein needs increase during pregnancy and lactation, extreme or very high-protein diets are generally not recommended. Pregnant women and nursing mothers require a balanced diet to ensure the health and development of their baby. Restrictive diets that prioritize protein over other macronutrients like carbohydrates can lead to nutrient deficiencies and may not provide all the necessary vitamins and minerals for both mother and child.

Potential Risks for Healthy Individuals

Even for those without pre-existing conditions, a high-protein diet is not without risks, especially over the long term. These risks are typically associated with an imbalance in nutrient intake and metabolic stress.

Digestive Issues

High protein diets, particularly those rich in animal products and low in fiber, can cause digestive problems. Fiber is essential for a healthy digestive system, and a lack of it can lead to constipation, bloating, and general discomfort. Balancing protein intake with plenty of fruits, vegetables, and whole grains can help mitigate this risk.

Dehydration and Nutrient Imbalance

Processing large amounts of protein creates more nitrogenous waste for the kidneys to filter, which in turn requires more water to excrete. This can increase the risk of dehydration if fluid intake is not sufficient. Furthermore, an overemphasis on protein can lead to a nutrient imbalance, displacing other crucial food groups that provide essential vitamins, minerals, and antioxidants.

High Protein vs. Standard Diet: A Comparison


Aspect	High-Protein Diet	Standard Balanced Diet
Protein Intake	Significantly above Recommended Dietary Allowance (RDA), often >1.2 g/kg body weight.	Meets or slightly exceeds RDA (0.8 g/kg body weight for most adults).
Carbohydrate Content	Typically low, can be restrictive depending on the diet plan (e.g., keto).	Balanced intake, providing a wide range of vitamins, minerals, and fiber.
Kidney Workload	Higher demand for filtration, potentially worsening function in those with pre-existing disease.	Normal workload, safe for healthy kidneys.
Nutrient Diversity	Risk of displacing fruits, vegetables, and whole grains, potentially leading to deficiencies.	Encourages a variety of food groups for a broad spectrum of nutrients.
Long-Term Sustainability	Often hard to maintain due to restrictiveness and potential side effects like constipation.	More flexible and sustainable for lifelong healthy eating.

Conclusion: Prioritize Personalized Nutrition

While a high-protein diet is popular for muscle building and weight loss, it is not universally beneficial and can even be dangerous for certain individuals. Anyone with pre-existing kidney or liver disease, inherited metabolic disorders, or those who are pregnant or breastfeeding should approach high protein intake with extreme caution and under medical supervision. For healthy individuals, moderation and balance are key to avoiding long-term risks such as nutrient deficiencies and digestive issues. The best approach is always to consult with a doctor or a registered dietitian to determine the protein intake and dietary plan that is right for your unique health needs.

Resources

For those considering dietary changes, seeking advice from a qualified medical professional is highly recommended.

The National Kidney Foundation provides comprehensive information on diet and kidney health, including recommendations for protein intake for those with kidney disease: https://www.kidney.org/kidney-topics/ckd-diet-how-much-protein-right-amount.

Who should not eat high protein: Summary List

Individuals with pre-existing kidney disease, as excessive protein intake can put extra strain on already weakened kidneys and worsen function over time.
Patients with liver disease or impairment, where a high protein load can lead to an accumulation of toxic byproducts like ammonia.
Those with inherited metabolic disorders, such as Lysinuric Protein Intolerance or Phenylketonuria, which prevent the body from processing certain amino acids properly.
People with a history of disordered eating, as overly restrictive high-protein diets can promote unhealthy eating patterns.
Pregnant or breastfeeding women, who need a balanced diet to support the health of both themselves and their baby.
Anyone prone to kidney stones, especially uric acid stones, as high intake of animal protein can increase the risk of their formation.
Individuals with a history of constipation, as high-protein, low-fiber diets can exacerbate digestive issues.

This list is not exhaustive, and anyone with concerns should consult a healthcare provider.

Frequently Asked Questions

For healthy individuals, moderate protein intake is generally safe. However, consuming excessive amounts over a long period can put extra strain on the kidneys. It is particularly risky for those with undiagnosed or pre-existing kidney conditions.

Symptoms of excessive protein intake can include digestive discomfort, bad breath, fatigue, dehydration, and nausea. Individuals may also experience an increased need to urinate due to the extra workload on the kidneys.

For individuals with advanced liver disease, a high-protein diet can be dangerous. The liver's reduced capacity can lead to the buildup of toxic substances like ammonia, potentially causing hepatic encephalopathy.

While protein needs increase during pregnancy, excessively high-protein diets are not recommended. A balanced diet with adequate carbohydrates, fats, and micronutrients is essential for both maternal and fetal health.

Yes, high intake of animal protein can increase the risk of kidney stones, particularly uric acid stones. This is due to increased urinary acid excretion and other metabolic changes.

Anyone with pre-existing kidney disease should avoid a high-protein ketogenic diet, as it can worsen kidney function. Other contraindications include certain metabolic disorders, pregnancy, and those at risk for kidney stones.

For individuals needing to manage protein intake, a consultation with a dietitian is crucial. In general, plant-based proteins, which are often accompanied by fiber and are lower in saturated fat, may be beneficial. Balanced intake from a variety of sources is often recommended.