Want to achieve your personal best physique?
Then the golden rule is: train right, eat with purpose, and recover appropriately - followed by a degree of patience. Of course, this needs to be done consistently and with a degree of patience. Whether it’s muscle and strength gains or weight loss – the macronutrient protein plays an important role for athletes.
Protein and amino acids
Dietary protein is comprised of individual building blocks, called amino acids, which are linked together in chains. Nine amino acids are considered as indispensable (essential), i.e. the human body cannot produce them itself and they have to be consumed via food regularly. Otherwise deficiency can arise.
Nine essential amino acids
- L-Histidine
- L-Isoleucine
- L-Leucine
- L-Lysine
- L-Methionine
- L-Phenylalanine
- L-Threonine
- L-Tryptophan
- L-Valine
The essential amino acid leucine belongs to the three branched-chain amino acids, known as BCAA’s. Leucine is not just a building block for muscle protein but is also known as the ‘superstar’ of all amino acids, as it acts as the strongest trigger for muscle protein synthesis. For example, whey protein is especially rich in leucine. The content of leucine and the total amount of essential amino acids is on average lower in plant-based sources of protein compared to animal-based sources.
Daily protein recommendations
The exact individual protein requirements are governed by many different variables e.g. form of nutrition, training load, training goal. Those who want to promote muscle growth or decrease body fat need to increase their protein intake. According to a recent meta-analysis, about 1.6 g of protein/kg body weight is optimal for maximal muscle and strength growth. Occasionally some well-conditioned athletes can tolerate a minimal increased benefit with a daily protein intake up to 2.2 g/kg body weight (1). Current recommendations for protein intakes during periods of calorie reduction for weight loss suggest similar amounts.
Especially for maximal muscle growth, the total daily protein intake should ideally be split evenly across 4 (up to 5) meals in regular intervals throughout the day (2,3). Breakfast, lunch, a snack after training, and dinner, as well as an additional snack before going to bed if needed, should therefore contain amounts of 0,3-0,4 (0,5) g protein/kg body weight.
What do I have to eat to take in protein?
Animal foods high in protein include meat, fish as well as seafood, eggs and dairy products. Plant-based sources of protein are for example pulses and legumes, soya products, meat substitutes such as Quorn, and nuts (learn more about protein-rich foods).
Protein-rich sports nutrition products such as protein powders (e.g. whey protein) or protein bars can help supplement the diet with high quality protein in convenient ways, aligned with the individual needs. A recent review with data just shy of 2000 participants showed that dietary protein supplementation can, if protein intake is less than 1.6 g protein/kg body weight per day, optimize resistance exercise training induced changes in muscle mass and maximal strength (8).
Can too much protein damage the body?
The stubborn myth that ‘a high protein intake damages kidneys’ is still around. Yet, there is no data to support this in healthy adults! Currently an upper limit for daily protein intake has not been set by the European Food Safety Authority (EFSA) due to a lack of supporting data. However, regular daily protein intakes of up to approx. 1,7 gram protein kg/body weight for healthy adults is harmless and safe according to the EFSA.
Muscle growth: positive net muscle protein balance is key
The proteins in our bodies undergo amazing dynamic processes. In our body, proteins are continuously broken down and rebuilt in order to preserve optimal function. Even muscle protein is subject to a constant change of synthesis and breakdown. This balancing act of mechanisms responsible for building and break down are influenced by several factors, such a level of activity and nutrition. If the goal is muscle hypertrophy, then the muscle protein synthesis must dominate over the break down so that it results in a positive net muscle protein balance. This can be achieved through a combination of repeated resistance exercise training and a corresponding protein intake via diet (1,2).
Body weight reduction and the importance of protein
Those who want to lose weight must aim for an energy deficit and should pay particular attention to protein: digesting and metabolising dietary protein is complex and leads to a noticeably higher energy expenditure in comparison to carbohydrates and fats. The so-called thermogenic effect (also called the diet-induced thermogenesis) is therefore higher (3). Besides, no other nutrient satiates better than protein: fat and carbohydrates have less of a satiety effect (3). Increased protein intake during a calorie-reduced diet can lead to increased body fat loss and can also minimise the loss of lean body mass (among other things muscle mass) (3). This is because during weight loss it’s not just body fat, but often also muscle mass that is lost. The smaller the loss of muscle mass the better the long-term stability of weight and health. This is due to muscles not only resulting in a fitter body, but they also burn calories. Incidentally: fat loss and concurrent muscle gain is possible under certain circumstances, but not without a high protein intake and very intense workouts (4). However, massive muscle gains cannot be expected during a calorie deficit.
Author: Corinne Mäder Reinhard, International Sports Nutrition Lead at Active Nutrition International. She has a postgraduate diploma in Sports Nutrition from the International Olympic Committee and is a certified Sports Nutritionist from the International Society of Sports Nutrition.