Protein requirements for muscle building: How much protein per day is optimal?

Proteins are the key building material for our muscles and are therefore essential for effective muscle building. As our body does not have large protein stores, protein must be supplied regularly through food. Intense exertion during strength training leads to micro-injuries in the muscles, which the body repairs with the help of protein and transforms into stronger muscle fibers. A sufficient protein intake therefore supports muscle protein synthesis and thus the growth and maintenance of muscle mass [1]. At the same time, protein fulfills many other vital functions - it forms enzymes, hormones, immune factors and more. A lack of protein would not only hinder muscle growth, but also impair numerous bodily functions. But how much protein is really necessary and can you eat too much? In the following, we take a scientifically sound look at the protein requirements for muscle building - from the optimum amount to the right timing and the best sources.

How much protein per day do you need to build muscle?

A person's basic protein requirement depends on body weight, activity level and individual factors. For healthy adults with no particular sporting activity, the recommended guideline is around 0.8 grams of protein per kilogram of body weight per day [2]. This amount is considered sufficient to ensure the normal maintenance of body tissue. So if you weigh 70 kg and do not exercise specifically, you need around 56 g of protein per day. This requirement is already covered by an average diet for most people.

However, the protein requirement increases significantly with targeted strength training and muscle building. Expert bodies such as the German Nutrition Society (DGE) recommend an intake of around 1.2 to 2.0 g of protein per kg of body weight per day for ambitious recreational athletes, depending on the amount of training and the training goal [1]. This recommendation is in line with international guidelines - the ISSN (International Society of Sports Nutrition) also specifies around 1.4 to 2.0 g protein/kg/day as the optimum range for muscle building [9]. Intake levels within this range have been shown in studies to be effective in building muscle mass, provided that training is appropriately intensive. It is important to understand that simply eating more protein alone will not make muscles grow - although the additional protein provides the "building blocks", the muscle also needs the growth stimulus of strength training [1].

In practical terms, this means that a strength athlete weighing 80 kg should consume approx. 96 g to 160 g of protein per day in order to optimally support muscle growth. A 100 kg athlete should consume around 120 g to 200 g per day. A meta-analysis of 49 studies found that no additional muscle building effect can be expected beyond approx. 1.6 g protein per kg body weight [5]. In other words: Those who already consume ~1.6 g/kg protein per day achieve maximum muscular growth with it; even higher amounts do not provide any additional benefit on average. Nevertheless, higher intakes are tolerated in certain cases - for example, when simultaneously losing fat or during very intensive training phases, an intake of over 2 g/kg can even be useful at times, as long as you are healthy and drink enough [3][1]. The World Health Organization (WHO) considers protein intakes of up to around twice the normal requirement (i.e. ~1.6 g/kg) to be safe for healthy people [3]. Only extremely high amounts of significantly more than 3 g/kg body weight are viewed with caution, as there is hardly any long-term data available. Overall, a protein intake of around 1.5 to 2 g per kg of body weight per day is on the safe side for optimal muscle building.

Protein timing: Does timing and frequency matter?

In addition to the total amount, protein timing - i.e. the time of protein intake - also plays a role in muscle building. It is often recommended to consume a protein shake or a meal containing protein directly after training in order to take advantage of the so-called anabolic window. It can indeed be helpful to consume protein promptly after a workout, but recent studies relativize the absolute dependence on the exact timing. Above all, it is crucial that the muscle has sufficient amino acids available at regular intervals throughout the day. A rule of thumb for optimal protein utilization is to divide protein into about 3-4 portions throughout the day [1]. Each of these meals should provide an average of around 20-40 g of protein (depending on body weight) to maximize muscle protein synthesis [6]. More than ~40 g at a time does not usually result in a stronger building effect - excess amino acids are then used for energy production [6]. Nevertheless, a large single portion is not harmful; the body can theoretically digest and absorb more than 30 g of protein in one meal, but the extra protein is not fully utilized for muscle building.

The decisive factor is therefore not so much a narrow time window directly after training, but that protein is continuously available for muscle building throughout the day. Studies show that the anabolic effect of strength training lasts for 24 hours or longer [7]. For example, if you have had a protein-rich meal 2-3 hours before training, you will still have amino acids in your blood after the workout and will not have to drink a protein shake every few minutes. Nevertheless, it makes sense to plan a meal with high-quality protein within 1-2 hours after training - simply to initiate regeneration and support muscle building. In practice, it is a good idea to include a good source of protein with every main meal (e.g. eggs for breakfast, meat/fish or pulses for lunch and dinner) and, if necessary, add a protein-rich snack (quark, nuts) or a shake after training. Some athletes also reach for slowly digested casein protein before going to bed (for example in the form of low-fat quark) to supply the muscles with amino acids overnight. According to studies, a portion of casein before sleep (approx. 30-40 g) can actually increase overnight muscle protein synthesis without impairing fat burning [9]. Overall, however, as long as the daily protein intake is correct and distributed roughly evenly throughout the day, timing is not an all-important factor [7].

Animal vs. plant protein: which protein source is better?

Proteins differ not only in quantity, but also in quality. Animal protein sources (such as meat, fish, dairy products or eggs) usually contain all essential amino acids in a favorable ratio for humans and are easy to digest. Plant proteins (from beans, lentils, cereals, nuts, etc.) often have lower levels of one or more essential amino acids (e.g. low lysine content in cereals, low methionine content in pulses) and are somewhat less digestible. Nevertheless, very good results in muscle building can also be achieved with a purely plant-based diet. Studies show no significant differences in muscle growth, as long as enough protein and calories are consumed overall [1]. According to the DGE, there is no clear advantage of animal protein over plant protein, as long as the overall protein supply is correct [1]. On the contrary: plant-based protein sources often have additional health benefits - they provide fiber, vitamins and phytochemicals and contain fewer unfavorable accompanying substances such as saturated fatty acids [1].

The best strategy is often to combine different protein sources. By cleverly combining plant-based protein sources (e.g. cereals + pulses such as rice with beans or lentils with potatoes), the biological value can be significantly increased so that the body receives all the necessary amino acids. Mixing animal and plant sources also combines the benefits of both [1]. It is also important to consider the total nutrient content of the protein sources: For example, fatty fish varieties provide valuable omega-3 fatty acids as well as protein, while red meat varieties contain a lot of iron but also come with cholesterol and saturated fats. A varied mix of lean meat, fish, eggs, dairy products and plant-based proteins such as pulses, soy products, nuts and whole grains is ideal for meeting both the protein requirements for muscle building and the micronutrient supply.

Some good sources of protein for muscle building are, for example

• Lean meat & poultry: e.g. chicken and turkey breast, lean beef
• Fish & seafood: e.g. salmon, tuna, prawns - rich in protein and omega-3 fats
• Eggs & dairy products: e.g. eggs, low-fat quark, Greek yogurt, cottage cheese
• Pulses: e.g. lentils, beans, chickpeas - plant-based protein bombs with fiber
• Soy products: e.g. tofu, tempeh, edamame - high-quality vegan protein
• Nuts & seeds: e.g. almonds, peanuts, chia seeds - provide protein plus healthy fats (but also lots of calories)

Protein powder and supplements: useful or superfluous?

Many amateur athletes turn to protein powders (whey, casein, vegan protein shakes) to conveniently cover their protein requirements. But are such food supplements really necessary? From a scientific point of view, the answer is: No, protein supplements are generally not absolutely necessary [1]. A balanced, protein-rich diet can usually cover the requirement without any problems, even for athletes who train intensively. The DGE makes it clear that there is no physiological reason for athletes to routinely increase their protein intake with powders or bars [1]. For example, 150 g of chicken breast or 200 g of low-fat quark each provide around 30 g of protein - spread over the day, you can easily get 100+ g of protein with normal food.

However, protein supplements can be very practical in individual cases. If you have little time to cook or are intolerant to certain foods, a protein shake can quickly provide you with high-quality protein. Especially after training, a shake is often easier to consume than a full meal. It is important to understand that powders are not a miracle cure - they simply provide protein in concentrated form. The effect on muscle building is the same as with protein from natural sources. It is permitted and scientifically recognized that protein as part of a healthy diet contributes to gaining and maintaining muscle mass [4] - this applies to protein from chicken breast as well as from whey powder. Anyone using supplements should pay attention to quality (e.g. certified products without undesirable additives) and see them as a supplement to an otherwise complete diet, not as a substitute for it.

Supplements can be helpful in special situations - for example, if someone has a very high protein requirement (e.g. competitive bodybuilders in intensive training phases) and hardly has an appetite for too much food, or when following a vegan diet with few protein sources, or during a strict diet in which every calorie is counted. In these cases, shakes offer a concentrated protein intake without additional calories from fat and carbohydrates. But even then, it is advisable to consume the majority of protein through normal foods in order to benefit from the accompanying nutrients. To summarize: Protein powders can support muscle building, but are not a prerequisite. The priority is always a protein-rich, varied diet - supplements are merely a convenient option if this cannot be implemented optimally.

Too much protein - harmful or unproblematic?

People often warn that a very high protein intake could damage the kidneys or otherwise put a strain on the body. In fact, the kidneys process the nitrogen compounds (such as urea) produced during protein metabolism. In healthy people, however, current studies show no negative effects of a high protein intake on kidney function [8]. In a meta-analysis of over two dozen studies, researchers found no evidence that a high-protein diet damages the kidneys of healthy people - on the contrary, the kidneys adapt and work efficiently [8]. However, it is important to drink enough so that degradation products can be excreted. However, people who already suffer from kidney disease must actually pay attention to a moderate protein intake and should follow medical advice.

Apart from the kidneys, there is the very pragmatic question: is it possible to eat too much protein? In purely physiological terms, yes - everything that the body does not need for tissue formation or other functions is either burned off or converted into energy (and ultimately fat). An extremely one-sided diet with very high amounts of protein is therefore neither necessary nor sensible. If you stay within the recommended range of 1.5-2.0 g/kg, you need not fear any negative effects. Even significantly higher amounts of 3 g/kg and more were well tolerated by strength athletes in studies over several months [9]. Possible short-term side effects of an excessively high-protein diet can be digestive problems (flatulence, diarrhea), especially if a lot of powder and little fiber are consumed. In the long term, excess protein combined with excess calories can also contribute to unwanted fat gain - excess calories (4 kcal per gram of protein) are always the main problem, regardless of whether they come from protein, carbohydrates or fat. However, one advantage of a high-protein diet is that protein is very satiating and can easily boost the metabolism, which can help with fat loss [10]. Overall, protein in moderation above the basic requirement is safe for healthy people and can even be beneficial depending on your goals - however, an excess will not result in additional muscle gains and should be avoided.

FAQ: Frequently asked questions about protein requirements and muscle building

How much protein per day do I need to build muscle?

Most recommendations are between about 1.2 and 2.0 grams of protein per kilogram of body weight per day for optimal muscle building. This range has proven to be effective. As a rule of thumb, you can assume approx. 1.5 g/kg. An 80 kg athlete should therefore consume around 120 g of protein per day. It is important that strength training is carried out at the same time - without a training stimulus, even more protein will not build muscle.

How much protein can the body utilize at once?

It is often claimed that the body cannot utilize more than ~30 g of protein per meal. This is not quite true. Studies show that around 20-40 g of high-quality protein is enough to maximally stimulate muscle protein synthesis [6]. In addition, the surplus is no longer used to build muscle, but is increasingly oxidized (consumed as energy). Nevertheless, the body can also digest and absorb larger amounts of protein - they do not simply evaporate. They just don't contribute to additional muscle growth. It therefore makes more sense to spread your protein intake throughout the day instead of eating 100 g all at once, for example.

Is timing really important, e.g. protein directly after training?

Compared to the total daily amount, timing is of secondary importance. However, there is no harm in consuming protein after a workout - many people do this routinely to initiate recovery. The key is to consume 3-4 protein meals throughout the day. Whether the protein comes directly after training or an hour later is of little importance for muscle building in the long term [7]. If you have eaten enough before training, there is no time stress. All in all, what counts is regular protein intake and meeting your daily requirements.

Do I need protein shakes or protein powder to build muscle?

No, protein shakes are not necessary. You can generally cover your protein requirements with normal foods (lean meat, fish, eggs, dairy products, beans, lentils, tofu, etc.). Shakes are merely a convenient supplement. If you find it difficult to get enough protein from your diet or want something light to eat straight after training, a protein shake can be useful. However, the effect on your muscles is the same as with protein from natural food - it's the total amount that counts. When taking supplements, make sure you choose high-quality products and use them as a supplement, not as a substitute for real meals.

Can too much protein be harmful?

In general, a high-protein diet is considered safe for healthy people. According to current studies, extremely high amounts of protein are usually unproblematic [8]. The often feared kidney damage caused by a high-protein diet has not been proven in healthy people. Nevertheless, it makes little sense to consume significantly more than ~2 g of protein per kg of body weight - the excess does not lead to additional muscle growth, but is only burned or stored as fat. In addition, very one-sided, protein-heavy diets can cause digestive problems. So stick to the usual recommendations and you won't have to worry about any negative effects. However, if you have existing kidney problems, you really need to be careful and consult a doctor to determine the right amount for you.

Are animal proteins better than plant proteins?

Animal foods usually provide a complete amino acid profile and are very easy to digest - which is why they have long been considered "better" for building muscle. However, a clever combination of plant proteins can achieve the same quality. Studies show that with a comparable amount of protein, muscle building is just as possible with a purely plant-based diet as with a mixed diet [1]. Plant-based protein sources also have health benefits (fiber, less fat). Ideally, you should use both: for example, a dairy product or eggs in the morning, a portion of pulses at lunchtime and lean meat or tofu in the evening - this way you get all the amino acids you need throughout the day.

Does a high protein intake help you lose weight?

A high protein content in your diet can actually help you lose fat. Protein has the strongest satiety effect of all macronutrients and slightly increases calorie consumption (due to the increased effort required for digestion). It is also important for those who want to lose weight that enough protein can minimize muscle loss in a calorie deficit. However, it is important to note that a calorie deficit is always necessary for weight loss - a lot of protein alone will not make the pounds tumble as long as the calorie balance is not negative. However, protein makes it easier to stick to a diet and maintain the hard-earned muscle mass. Studies on overweight people have shown that with an identical calorie deficit, a higher protein intake leads to more fat loss and less loss of fat-free mass [10]. In practice, when losing weight you should therefore make sure that you consume at least the above-mentioned 1.2 g/kg protein (if not up to 1.6 g/kg) per day. This protects the muscles and at the same time promotes a feeling of satiety.

Conclusion

To build muscle successfully, you need a combination of hard training and sufficient protein intake. A target of around 1.5-2 grams of protein per kilogram of body weight per day has been established - this amount generally provides sufficient building blocks for the muscles without placing unnecessary strain on the body. If you incorporate high-quality protein sources into your diet throughout the day and make sure you eat a balanced diet, you will create the ideal conditions for muscle growth. Food supplements such as protein shakes can be helpful, but are not compulsory. Ultimately, what counts is continuity: with regular training, sufficient protein and patience, you will build muscle step by step.

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