All About Protein

If you walk into the 'bro' area of any gym, you will hear rumours circulating that more protein equals more muscle. Although not entirely false, this mindset has lead to a lot of misconceptions regarding protein intake.

The current recommendation for protein intake in athletes ranges between 1.2-2.0 g/kg of body weight [BW] per day (ACSM, 2016). The only time that protein intake above this is recommended is during periods of temporary energy restriction (such as a weight cut). At this point, an intake of up to 2.2 g/kg BW per day can help to preserve lean muscle mass throughout the deficit period. As a whole, intakes above 2.2 g/kg BW have not been shown to be beneficial.

Witard et al., 2019

Now, what does this look like for an athlete? Let's say you are a 65 kg female, you would need between 78 and 130 kg of protein per day. Most athletes in North America easily achieve this. Notice that I am using her total body weight? There is some debate as to whether total body weight or lean body weight (excluding fat mass) should be used. I often have leaner (about sub 20% body fat females and sub 14% body fat males) use their total body weight. Why? Mostly out of ease of calculation and a few extra grams is not a huge deal. For those with higher body fats, taking protein down at bit to reflect their current muscle mass is more appropriate. What does this look like? Let's say you have a male that is 110 kg and around 25% body fat (or has noticeable extra body fat). His lean body mass would be 82.5 kg. This would put his protein intake between 99 and 165 g of protein. If he is inactive, I would keep his protein here. If he is resistance training and trying to lose body weight, I would keep him at the top end of this recommendation.

Usually, I have athletes set protein at the top end of this recommendation. Why? Most athletes come to a nutrition coach trying to modify their body composition and/or improve their performance. Both of these, require protein intake at the higher end. Protein intake for long-term good health does not need to be at the upper end all of the time.

Do I need protein right after a workout?

Generally yes, it is recommended to consume a post-workout recovery meal. The post-workout window for refuelling is a lot longer than most people think. Try and eat within 60-90 minutes following training. You don't have to inhale 50 g of pure whey protein within 15 seconds of your last set. You won't instantly go catabolic, I promise. It is more important to consume an appropriate amount of energy (and protein) over the day than directly after a workout. What I mean by this is, it would be better to eat 3-4 meals a day, evenly splitting your macronutrients as opposed to having a perfect post-workout meal and forgetting to eat (or overeat) the rest of the day.

As you can see in the figure below, muscle protein synthesis (MPS) is sustained for 24-48 hours post resistance training. This means that having a consistent source of protein (and calories) throughout a training day, and days following is important for recovery and building muscle. This is why keeping a consistent and balanced diet is more important than focusing solely on post-workout protein intake.

Churchward-Venne, et al. 2012

The figure below gives an example of the most optimal way that would maximize our dietary protein intake for maximum absorption. Most people fall under category A, with a low protein breakfast and a larger amount in their evening meal. Some also fall under category C, with dietary above what they need and an extremely high amount at their evening meal. Both are not the ideal method to maximize MPS while staying within an appropriate total energy intake.

Moore, et al. 2019

What type of protein should I eat and how much?

Both carbohydrates and protein play a role in glycogen replenishment and muscle tissue repair. A lot of people consume a whey protein shake following their session. This is a good start as whey protein is high in leucine. Leucine stimulates the mammalian target of rapamycin (mTOR) signalling pathway. This pathway is responsible for MPS (Stark, et al. 2012). High sources of leucine include dairy products, meat, poultry, fish, legumes and soy (the latter two are not digested quite as easily).

A factor that many forget is to include a carbohydrate source with their protein. Leucine has both an insulin dependant and insulin-independent mechanism to promote protein synthesis. By consuming a fast-acting carbohydrate source with a leucine-rich protein source, we can reap maximum MPS. Whole, real foods are always better than supplements. Easy examples would include Greek yogurt with fruit and honey or a simple sandwich. However, if you are not able to get whole food in, supplements such as a whey protein shake with fruit such as a banana or a carbohydrate supplement such as dextrose mixed will also work.

Aim for 15-25 g of protein post work out and 30-75 g of carbs. If you are a smaller athlete, 15 g of protein and 30-50 g of carbohydrates (30 g if it's lower volume resistance training and towards 50 g if it's endurance and/or more metabolically taxing). 25 g of protein if you are a larger athlete with the carbohydrates adjusted according to the type of exercise performed. Can you consume more than that? Yes, but our body does have a limit on how much protein can be absorbed at once. One study found no additional benefit to muscle protein synthesis when consuming 40 g as opposed to 20 g of protein directly post resistance training (Moore, et al. 2009).

What happens if I eat more protein than I need?

As much as some people may like to believe, consuming more protein than you need will not result in more muscle. Unless you are a complete beginner, or on steroids, muscle takes a long time to build. Extra calories (even if protein) will be stored as fat. This does not mean you need to be hyper concerned about eating exactly what you need all of the time. Your body is under constant repair and turnover. Fat tissue is being synthesized and broken down constantly just like muscle tissue. What matters is that you consume enough protein for your size and activity level. If you need more calories to fuel your sport, it should be consumed primarily as carbohydrates followed by fat.

What about plant-based protein?

Protein from plant-based sources such as cereals/grains, nuts, legumes, seeds and soy tends to be of lower quality. Protein quality is assessed by digestibility and net protein utilization both of which, animal proteins score higher. The Protein Digestibility Corrected Amino Acid Score (PDCAAS) is a way to assess a dietary protein's ability to meet our body's essential amino acid requirements. A score of 100 would indicate the best value. The PSCAAS value of whey, milk and eggs is 100 whereas most plant foods range from 25-80. A lower value would be wheat gluten at 25 and a higher value would be chickpeas at 74 (Berrazaga, et al. 2019). The lower PSCAAS value seen in plant-based proteins is due to their incomplete nature. There are both essential and non-essential amino acids (the building blocks of proteins). Essential amino acids are amino acids that we must attain from the diet. Two of our essential amino acids are lysine and methionine. Cereal grains such as wheat are deficient in lysine while legumes such as peanuts are deficient in methionine. Luckily, cereal grains and legumes are often paired together in dishes such as rice and beans or peanut butter on toast. When complementary proteins are combined, our body is able to synthesize all essential amino acids. The PSCASS ranking is looking at food in isolation, so if you combine multiple sources of plant proteins your diet won't be deficient in amino acids.

That being said, plant proteins are not as easily digested as aminal proteins due to the difference in structure, Plant proteins are also connected to starch polysaccharides and fibre that can impede protein absorption. Aim towards the upper end of the 1.2-2.0 g/kg BW recommendation as not all of the protein you eat will be as easily digested. For example, one study by Gorissen, et al. (2016) found that MPS was higher in those who consumed 35 g of casein as opposed to 35 g of wheat protein. 60 g of wheat protein was needed for the equivalent response to 35 g of casein in MPS. Therefore, you will have to consume more protein on a plant-based diet than a diet that includes animal-based protein.

So what?

Overall, protein is an essential part of our diet. As an athlete, your protein needs will be higher but not above 2.2 g/kg BW a day. Consuming both a carbohydrate and protein source within 60-90 minutes following training can improve your rate of recovery. This does not negate the importance of a balanced diet throughout the day. Plant protein sources also work to fulfill protein requirements, but you will need to consume more of it for the same benefit.

References

American College of Sports Medicine [ACSM](2016). Nutrition and Athletic Performance. Medicine & Science in Sports & Exercise. 48(3): 543-568

Berrazaga, I., Micard, V., Gueugneau, M., Walrand, S. (2019). The Role of the Anabolic Properties of Plant-versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical Review. Nutrients. 11(8): 1825

Churchward-Venne, T., Burd, N., Phillips, S. (2012). Nutritional regulation of muscle protein synthesis with resistance exercise: strategies to enhance anabolism. Nutrition & Metabolism. 9(40)

Gorissen, S. et al. (2016). Ingestion of Wheat Protein Increases In Vivo Muscle Protein Synthesis Rates in Healthy Older Men in a Randomized Trial. Journal of Nutrition. 146(9).

Moore, D. (2019). Maximizing Post-exercise Anabolism: The Case for Relative Protein-Intakes. Frontiers in Nutrition. 65:147

Moore, D., Robinson, M., Fry, J., Tang, J., Glover, E., Wilkinson, S., Prior, T., Tarnopolsky, M., Philips, S. (2009). Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. American Journal of Clinical Nutrition. 89(1): 161-168

Stark, M., Lukaszuk, J., Prawitz, A., Salacinski, A. (2012). Protein timing and its effects on muscular hypertrophy and strength in individuals engaged in weight-training. Journal of the International Society of Sports Nutrition. 9:54

Witard, O., Garthe, I., Phillips, S. (2019). Dietary Protein for Training Adaptation and Body Composition in Manipulation in Track and Field Athletes. International Journal of Sport Nutrition and Exercise Metabolism. 29(2): 165-174.