Protein consumption is always a hot topic among training enthusiasts. It is now universally accepted that extra protein is a necessary companion for those who are training intensely, but there is confusion about how much should be in our diet and whether lots of protein in the diet causes renal stress.
Firstly renal stress is a myth. Even studies such as the one published by Poortman and Dellalieux (2000), which have prescribed protein intake of up to 2.8 g/kg bodyweight (which would be perceived as a lot) have shown absolutely no adverse effects to the kidneys. Instead there is evidence to suggest that people who have pre-existing kidney disease should avoid high protein diets, which is perhaps where the myth began.
But the question of how much is optimal as opposed to safe is a more complex one. The current Recommended Daily Allowance (RDA) of protein is 0.8g of protein per kg of body weight according to the Food and Nutrition Board, Dietary Reference Intakes (DRIs). However this amount was intended for sedentary populations and only to prevent deficiency and so would not be appropriate for those who participate in regular bouts of resistance training. So how much is the right amount if we are training hard? To answer that requires a bit of background knowledge on the structure and function of protein.
What is Protein?
Protein is made up of amino acids - often termed ‘the building blocks of life’. It’s an appropriate name because amino acids are responsible for:
- our structure (contractile and fibrous proteins)
- the production of hormones
- the production of enzymes
- the production of immune chemicals
- the production of transport proteins
- the replacement of worn out cells
- growth and repair
Amino acids are made available to the body when protein is broken down during digestion. While some amino acids can be manufactured by the body, there are nine which can only be absorbed from the food we eat and so are termed as essential amino acids. The amino acids then go into circulation forming the plasma pool of amino acids. This is essentially a reserve tank that circulates in the bloodstream, providing the cells with their amino acid needs. However this tank must be constantly replenished. While fats and carbohydrates have highly efficient storage mechanisms in the body, protein requires constant dietary intervention to maintain amino acid availability. Keeping protein in our system is a bit like keeping a bath full of water when you’ve lost the plug - you have to keep on topping it up. But it’s vital that we do keep the tank full because without a steady stream of amino acids the body falls into a net negative protein balance and we start to see enzyme and structural protein degradation. Obviously this is to be avoided for our general health but for strength training populations it is critical that we have a readily available pool of amino-acids for anabolic (building) processes to occur. Creating an anabolic environment is one of the key principles for improving body composition and long-term health as is explained in this article.
While protein, carbohydrates and fats all contain carbon and hydrogen molecules, nitrogen is unique to protein. It is possible to track this nitrogen in the bloodstream using stable isotope tracers. This allows researchers to take sample populations (such as those who train intensely with weights) and measure their amino acid status against certain dietary and exercise protocols. This is the method often used to make recommendations on how many grammes of protein are optimal per kilogram of body weight. It can determine not only the amount that is effective for muscle protein synthesis but also how much is too much. This is because the tracer method can differentiate between four states:
- Deficiency where protein synthesis is directed only to essential organs,
- Accommodation where nitrogen balance is achieved with a decrease in physiological processes
- Adaptation in which protein is made available for hypertrophy
- Excess in which amino acids are oxidized for energy (converted to glucose and ketones) and/or excretion via urea.
In October 2012 Szedlak and Robins published a literature review titled protein requirements for strength athletes in the Strength and Conditioning Journal. They cited research using the tracer method that would recommend a more appropriate amount of protein for avid lifters to be 1.5 - 1.7 g/kg bodyweight in order to fall under “adaptation” status. Anything above that amount would fall under the category of “excess”, which could not be utilized by the body for muscle protein synthesis.
How Much Protein Per Sitting?
But of that daily recommendation of 1.5 - 1.7g/kg how much should we be consuming per sitting? If we take for example an 75kg person it would mean that that person would need to consume 127.5g of protein per day if we work from 1.7g/kg of body weight. How do we break that amount up?
A study published by Moore et al (2009) demonstrated that when college-aged weight-trainers drank 0g, 5g, 10g, 20g, or 40g of protein after a weight training session, muscle protein synthesis was maximally stimulated at the 20g dose. Interestingly, there were no further increases in muscle protein synthesis at the 40g dose.
Similarly Symons et al (2009) found that when young and elderly volunteers were given 30 or 90g of dietary protein in a single meal, the 30g dose maximally stimulated muscle protein synthesis. Like Moore et al., there were no further increases in muscle protein synthesis at the higher dose.
These two studies would suggest that for optimal muscle protein synthesis we need not consume any more than 20-30 grams of protein per sitting, which again reinforces the need to spread our protein intake over the course of the day rather than consuming a large amount in one sitting.
Some resources suggest taking your recommended daily amount and dividing it by the number of meals you consume per day. This makes sense but in some cases this will mean consuming more than 30g in a sitting. If you take for example a 95kg person who eats three meals per day you get the following amount:
95 kg body weight
95 x 1.7 = 161.5
each meal = 53.8g
Where possible we would recommend consuming smaller but more frequent meals to optimize the plasma pool of amino acids. If that’s not practical though - and for many it’s genuinely not - we would still recommend consuming the full 54g. Our reason for this is that there are other benefits to consuming protein besides just muscle protein synthesis.
For example Layman et al (2003) found that reducing the meal time carbohydrate:protein ratio from 3.5:1 to 1.5:1 decreased body fat, maintained muscle mass, reduced triglyceride concentrations and LDL cholesterol, improved the sense of satiety after eating and improved blood glucose management.
So if at times you need to go above the 20-30g threshold for protein in order to meet your daily targets, go ahead. While the extra protein wont result in increased muscle protein synthesis, the change in ratio between carbohydrate and protein will do you good for a variety of other reasons. In our opinion it would be better to be sitting slightly above the daily recommendation than below it.
Just after training is a key window for muscle protein synthesis though so make sure you nail down at least 20-30g of protein immediately after training with a readily available carbohydrate source. Many people find that the most practical way of managing this is through the use of protein powders although some people are able to stomach a chicken breast or two immediately post-training. For the rest of the time though we strongly recommend you get your protein from natural, whole foods.
Our Guide To Primal Eating
At Primal Strength we provide all of our members with a comprehensive 45 page eating plan that reflects these recommendations as well as optimal amounts of healthy fats and carbohydrate along with meal suggestions and a success guide. We are big fans of getting our nutrition from natural whole foods where practical and we do recommend a protein source with every meal or snack to keep our amino acid pool topped up.
Poortmans JR, Dellalieux O.
Int J Sport Nutr Exerc Metab. 2000 Mar;10(1):28-38.
Do regular high protein diets have potential health risks on kidney function in athletes?
Moore DR, Robinson MJ, Fry JL, Tang JE, Glover EI, Wilkinson SB, Prior T, Tarnopolsky MA, Phillips SM.Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr. 2009.
Symons TB, Sheffield-Moore M, Wolfe RR, Paddon-Jones D. A moderate serving of high-quality protein maximally stimulates skeletal muscle protein synthesis in young and elderly subjects. Journal of the American Dietetic Association, 2009.
Layman, J. Nutr, 133: 216S-267S, 2003. Layman and Walker, J. Nutr., 133: 405-410, 2003 Layman et al, J. Nutr., 133: 411-417, 2003 Layman and Walker, J. Nutr., 136: 319S-323S, 2006 Jitomer and Willoughby, J. Med. Food, 11: 606-609, 2008