Protein quality vs. protein quantity – what is more important for muscle growth and health?

Protein is essential for the body – but the question of how much we need and which sources are best is hotly debated. While some focus on consuming as much as possible and rely on protein shakes, others swear by the right combination of natural foods. Current research shows that quantity alone isn't the deciding factor. The quality of the protein is at least as important – as is the art of optimally combining both factors.

The basics: What exactly is protein?

Proteins, also known as polypeptides, are vital building blocks of the body. They consist of amino acids, which in various combinations perform numerous functions – from muscle building and wound healing to metabolism. The body can produce some of these amino acids itself, while others – the essential ones – must be obtained through food.

The quality of a protein is primarily measured by how well it can supply the body with these essential amino acids. The chicken egg serves as the traditional reference point with a biological value of 100. .

The quantity: How much protein does the body really need?

The recommended protein intake depends heavily on age, activity level, and health status. For healthy adults between 19 and 65 years of age, the German Nutrition Society (DGE) recommends 0.8 grams per kilogram of body weight daily. For a person weighing 70 kilograms, that would be about 56 grams of protein per day – an amount that can easily be achieved with a balanced mixed diet.

Higher demand among certain groups

However, certain groups of people have an increased protein requirement:

• Athletes and physically active people : The International Society of Sports Nutrition (ISSN) recommends 1.4–2.0 g/kg body weight daily to support muscle growth and recovery. In special situations such as energy deficit or high-intensity training, up to 2.2 g/kg can be beneficial for short periods. .

• Older adults : From the age of 50, muscle mass often decreases (sarcopenia). A higher intake of approximately 1.0–1.2 g/kg is recommended to counteract this. The European Society for Clinical Nutrition and Metabolism (ESPEN) even recommends 1.0–1.5 g/kg for older adults. .

• Pregnant and breastfeeding women : During this phase of life, the requirement increases to about 70 grams per day. .

According to current research, a protein intake above 2.2 g/kg body weight offers no additional benefits for healthy individuals. .

Is too much protein harmful?

For healthy people, a high protein intake – even up to 3 g/kg body weight – is generally unproblematic. Studies show no evidence of kidney damage in otherwise healthy individuals. However, a high-protein diet requires consistent fluid balance monitoring, as the increased urea production must be excreted via the kidneys. .

Problems arise less from the amount of protein itself, but from an unbalanced diet: Those who drink several shakes daily but consume hardly any carbohydrates, fiber or fluids risk digestive problems, fatigue and unnecessary strain on their metabolism. .

Quality: What makes good protein?

The quality of a protein is determined by two factors:

1. The amino acid profile : Does the protein contain all essential amino acids in sufficient quantities?

2. Digestibility : How well can the body absorb and utilize the protein?

Animal proteins (meat, fish, eggs, dairy products) generally have a more complete amino acid profile and a higher biological value than plant proteins. They contain a particularly high amount of leucine, the amino acid that most strongly stimulates muscle growth. .

The quality boost: Clever combinations

The key advantage of plant-based proteins lies in the possibility of significantly increasing their biological value through clever combinations. Classic examples include:

• Potatoes with egg (biological value over 130)

• Dairy products containing grains (e.g., muesli with milk)

• Legumes with grains (e.g. lentils with rice or beans with corn)

These combinations enable a high-quality protein supply without the use of special supplements or industrially enriched products. .

Are high-protein products necessary?

The answer from the professional associations is clear: No. Adequate protein intake is easily achievable with both animal and plant-based foods. High-protein products are often highly processed, significantly more expensive, and offer no clear health benefit for healthy adults. .

Dr. Elisabeth Schieffer from the Hannover Medical School emphasizes: "Supplementation is not necessary for the vast majority of situations and is not recommended." .

The distribution: When to eat protein?

Besides quantity and quality, the timing of protein intake also plays an important role. Studies show that a protein intake of approximately 20–40 grams per meal has the best effect on muscle protein synthesis. The daily amount should therefore be evenly distributed across 3-4 meals (every 3-4 hours). .

For athletes, consuming protein after training (≤ 1 hour) is not a mandatory requirement for muscle growth – the total daily amount seems to be more important. .

Protein and bone health: A nuanced picture

For a long time, there were concerns that a high protein intake could damage bones. Current research largely refutes this concern. A guideline on protein intake and bone health, commissioned by the German Nutrition Society (DGE), shows:

• There is no evidence that higher protein intake increases the risk of fractures in the general population. .

• In people over 65, the risk of hip fractures may even be reduced with high protein intake. .

• Protein is important for the health of the musculoskeletal system. .

Practical implementation: How to optimize your protein intake

Table: Comparison of protein-rich foods

Five golden rules for optimal protein intake

1. Adjust the amount to the need : 0.8 g/kg for the general population, 1.4–2.0 g/kg for athletes, 1.0–1.2 g/kg for the elderly.

2. Pay attention to quality : Prefer whole protein sources – natural foods over isolated products. .

3. Combine cleverly : Mix plant and animal proteins or combine plant proteins with each other to increase their biological value. .

4. Distribute evenly : 20–40 g of protein per meal over 3–4 meals a day .

5. Drink enough fluids : With a high-protein diet, drink at least 2.5–3 liters of fluid daily to support the kidneys. .

Conclusion

The debate about protein quality versus protein quantity cannot be answered with a simple either-or. Both factors are important and interact with each other. The quantity must correspond to individual needs – what applies to a top athlete is excessive for an office worker. The quality determines how efficiently the body can utilize the ingested protein.

Those who focus on a balanced mix of natural protein sources, combine meals effectively, and distribute their daily intake evenly are on the right track. High-protein products and supplements are unnecessary for the vast majority of people. The best protein strategy isn't about extreme quantities, but about well-considered quality and a balanced diet.

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Official sources & studies:

• DocMedicus Health Encyclopedia: Protein intake, water requirements and kidney function in athletes (November 2025)

• aponet.de (ABDA): Protein Check – Which foods provide a lot of protein? (March 2025)

• German Nutrition Society (DGE) Mecklenburg-Vorpommern: Influence of protein quantity and type on bone health (May 2023)

• Men's Health: How much protein do you really need? (May 2025)

• MedMedia / nextdoc: Myths & Facts – High-Protein Products (January 2026)

• Sports medicine journal: Protein supplementation – What does the scientific evidence show? (July 2025)

• Optimum Nutrition: Are the usual protein recommendations too low? (October 2025)

• Medical Tribune: Do high-protein foods promote health? (June 2021)