The Truth about Protein

How much protein do I need?

What are the best sources of protein?

How should I space out my protein intake?

There’s a lot of information available on protein consumption, much of it contradictory and paired with a fundamental misunderstanding of protein’s importance for your health. Before I get into what the science tells us, we need to make an important distinction between two terms that will become important for our discussion:

• Protein Requirements

vs

• Protein optimization

When researchers are establishing requirements, they mean the amount of protein required to prevent a deficiency, along with the associated muscle loss that would result. Whereas protein optimization means identifying the amount required to maximize muscle health. Since our goal is to improve body composition, we are going to focus on optimization. So the question shifts from how much do you need to how much can you effectively use?

Protein. This dynamic macronutrient is the building block for every cell in our body, so it’s about time to spread some science-based information about it.

If you’re not particularly conscious of your food choices or perhaps very mindful due to leading a vegetarian lifestyle, it’s likely you’re under consuming protein. I know, I know, you’ve probably heard that enough times to make your ears fall off. But in this chapter, I’m going to teach you why protein is so important, then I’ll provide actionable advice on how to leverage this nutrient to look and feel your best.

Muscle is vital to your body recomposition efforts, making it critical you leverage all of the variables you can to maintain it during periods of weight loss. But protein’s role in body recomposition is not exclusive to muscle maintenance and growth. Quite the opposite: two unique qualities of protein that will be discussed throughout this book make it important for fat loss as well:

1. Protein is the most satiating macronutrient.  Meaning as you consume more protein, you reach fullness faster and stay full longer. I don’t know about you, but if I can appease my appetite during a low-calorie diet, that’s a win.
2. Protein has the highest thermic effect of feeding. This means that in order to metabolize protein, you have to expend more calories than you would for carbohydrate or fat metabolism. For instance, carbs and protein both have a caloric value of 4 calories per gram. Protein, however, is more energetically expensive to metabolize, meaning the net calories you absorb from protein are less than you would from the same amount of carbohydrates.

Although these benefits are clearly relevant to our body fat reduction efforts, they are still secondary to protein’s principal role of facilitating muscle growth. Assuming you’re engaged in some sort of exercise, it will be helpful to understand protein’s function in restructuring the body. You work hard in the gym, so why would you skimp on the very fuel your muscles need to grow?

Nerd Alert. Although resistance exercise alone helps build muscle, we require protein and its constituent amino acids to facilitate the repair and remodeling of skeletal muscle in response to exercise. We call this the adaptive response, and it’s simply the way in which your muscle changes after exercise.

Although we’d like to make our recommendations based entirely on the scientific literature, there are some important practical limitations. In the long-term, you should be interested specifically in muscle growth (hypertrophy) or maintenance. However, when it comes to evaluating the effectiveness of a given food source or exercise to achieve this result, scientific research is often limited to very short evaluation periods. For example, feeding someone 3 whole eggs and measuring the response in the immediate 5 hours after food ingestion rather than what happens over 12 weeks of consuming eggs. Although these measures are useful, it doesn’t necessarily predict the long-term efficacy of that particular protein source[1].  

The skeletal muscle adaptive response is often characterized by a balance between growth (anabolic) and breakdown (catabolic) reactions of the muscle. Anabolic reactions can also be termed muscle protein synthesis (MPS) while catabolic reactions can be referred to as muscle protein breakdown (MPB). When MPS exceeds MPB we are in a positive net protein balance. When this balance is sustained over time it creates an ideal environment for muscle growth.

Although resistance exercise alone will augment MPS, breakdown is also increased, and so you’ll need to consume enough amino acids to achieve a positive protein balance [2]. 

Take Home: we have two stimuli to initiate and support muscle growth: resistance exercise and protein intake.

Post-exercise, your muscles are primed for nutrient intake.  But not all nutrients are created equal. Amino acids play an essential role in muscle adaptation during the post-workout period. And even among amino acids, the body shows a clear preference for leucine when it comes to synthesizing new proteins [2] [3, 4].

Given the importance of leucine, we can also conclude that some protein sources are better than others. As you’ll learn next, animal-based proteins contain a more complete amino acid profile and therefore demonstrate a more robust effect on muscle protein synthesis. Plant-based sources, on the other hand, may need to be combined in certain ways to boost their anabolic properties. To be clear, if you follow a plant-based diet, you can still optimize muscle health and even growth but you’ll need the information that follows to ensure you’re making up for any inherent nutrient shortfalls. 

First things first, what are the comparable amino acid profiles among competing sources?

In the lab, when assessing the essential amino acid composition of a protein source we use the ratio found in human skeletal muscle as the optimal benchmark. It’s these particular amino acids that ultimately dictate the strength of the signal telling the muscle to begin building, and themselves represent the tools necessary to make it happen. Although all amino acids are required to build new muscle, essential amino acids cannot be synthesized in the body and so are required from the diet.

Referencing the table above, you can see quite clearly that plant-based sources fail to provide the balance of amino acids required to optimize the muscle growth response, whereas animal sources achieve and exceed the established thresholds.

Keep in mind it’s not just the profile of essential amino acids that’s important, but how many ultimately become available to the muscle to support its repair and remodeling following exercise. Metabolism is an inefficient process and some nutrients that enter the mouth may never make it to the tissues that require them. Unfortunately, plant-based protein sources are inferior in this regard as well. 

The body has a harder time digesting and absorbing protein from plants than it does protein from animals, further weakening its muscle-building potential. The literature suggests only 45-80% of these amino acids become available to muscle after digestion and absorption, compared to more than 90% for animal-based sources. This inefficiency is purportedly due to “anti-nutritional” factors that interfere with digestion and absorption [5]. Whether it’s primarily driven by high levels of insoluble fiber, trypsin inhibitors, or tannins in legumes, the impaired absorption could further degrade the muscle-building ability of plant sources [6] [7].

Personally, I’ve chosen to gravitate toward an increasingly modest consumption of animal-based products. Consequently, I’ve had to identify strategies that can be leveraged to still optimize my muscle building potential. Here are some strategies I can recommend to compensate for the deficiencies of plant based sources:

1. Consume more plant-based options in an effort to achieve essential amino acid benchmarks:  
2. Consideration: Accounting for the macronutrients in plant sources (high in carbohydrates and potentially fat as well) – if you don’t, this could result in the overconsumption of certain nutrients resulting in unwanted weight gain.
3. Combine multiple sources to mimic the optimal amino acid composition:
4. Consideration: I’m not suggesting you need to memorize every plant-based source’s amino acid profile – fortunately, that’s no longer necessary. Available today is a wide range of plant-based protein powder blends that combine a number of vegan-friendly sources to create a complete amino acid profile when consumed together.      

Practical Protein Recommendations. 

If your goal is muscle growth, the science suggests that a minimum of 20g of protein at each meal should optimally stimulate anabolism. Approximately 2.5g of that should be leucine, and your protein source should otherwise have a strong overall amino acid profile. As we just covered, animal-based options are going to have a leg up here, removing some of the guess work, but you can still achieve these amino acid requirements with plant-based sources. Be sure to leverage the increasing availability of complete plant-based protein sources available on the market (recommended brands: True Nutrition, Sunwarrior, or Vega).

The 20-gram threshold recommended here is an approximation and is often higher for older adults (45 years and older may require ~40g per meal).  We find these amounts from short-term studies that compare protein dosages in a single meal. This research has characterized the optimal dose to be around 0.25 grams of protein per kilogram of body weight [8]. This is not to say you couldn’t potentially benefit from more protein - only that consuming more than this amount in a single sitting is superfluous in its contribution to muscle growth. As we will discuss later, total daily protein intake is going to be more influential than the amount in a particular meal.

Any complete protein supplement should meet the above criteria in one serving. But don’t overlook whole foods, several of which are rich not only in amino acids but also micronutrients important for your overall health [9].  If you would prefer a steak, eggs, or milk to protein supplements, you are certainly in good hands. To meet our criteria, any of the following would do:

Figure 2.

Now you know what to eat, and how much, but when is the best time to eat protein?

For instance, do you have to eat protein immediately after a workout? How long do you have?

Supplement brands, gyms, and lay publications often promote the idea that the post-workout phase lasts just a short while, with some outlets defining it as 120 minutes and others as little as 30 minutes. They call it the “anabolic window of opportunity” and claim that to optimize muscle growth and offset catabolism, an appropriate amount of protein must be consumed within it. This implies that any protein supplementation (whole food or isolated) must be consumed within this timeframe to optimize the response and immediately offset any catabolic processes.

The rationale behind this idea is somewhat sound, since it is true that exercise sets the stage to make the most efficient use of amino acids for building new muscle. However, research shows that the window of opportunity is much longer than most think, and it actually lasts for at least 24 hours [6]. This means that as long as your regular diet contains enough protein, you can continue your normal eating habits without worrying about stuffing yourself immediately after each workout.

My suggestion.  Focus on consuming at least 30 grams of protein in 3-5 meals daily to ensure you’re getting enough leucine regardless of the protein source you’ve chosen. Select an eating pattern that best suits your lifestyle and don’t be too concerned about the timing of protein immediately following your workout session. Finish your exercise, rehydrate, and eat when you’re ready – slamming a protein shake as you finish your last set isn’t necessary.

As you now know, resistance exercise and protein ingestion together have a synergistic effect on muscle building. Think about it: we provide stimulus to the muscle to grow, then provide the resources to facilitate that process. Although both would augment muscle growth on their own, together they have a compounding effect that lasts for hours, maybe even days, following your last weight training session. All you need to know is that by engaging in vigorous resistance exercise at least 4 times a week, you can dramatically improve your body’s ability to use protein around the clock to construct your new physique. All of this can be accomplished in a 25-minute workout with adequate intensity.

Chapter Take Home: If you want to maximize skeletal muscle adaptations you should focus on determining and implementing the following:

1. Daily protein requirements: You should consume 0.75g - 1.5g of protein per pound of bodyweight daily or 0.10g - 0.15g of protein per pound of bodyweight per meal [10]. (These estimates are for young healthy people; the elderly would require more: around .18 - .20g per pound of body weight per meal)
2. Protein quality: Focus on protein sources that meet critical thresholds of leucine with a supporting cast of essential amino acids. Identify supplement and whole-food options that are consistent with your preferences and health circumstances.
3. Meal Timing: Identify an eating strategy that fits your lifestyle. You don’t have to be too strict about this if you generally achieve your daily protein requirements.

Whatever your dietary or lifestyle circumstances, intelligently design your approach to optimize consistency, adherence, and enjoyment. 

Citations:

1. Mitchell, C.J., et al., Acute post-exercise myofibrillar protein synthesis is not correlated with resistance training-induced muscle hypertrophy in young men. PLoS One., 2014. 9(2): p. e89431. doi: 10.1371/journal.pone.0089431. eCollection 2014.

2. Churchward-Venne, T.A., et al., Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial. Am J Clin Nutr., 2014. 99(2): p. 276-86. doi: 10.3945/ajcn.113.068775. Epub 2013 Nov 27.

3. Burd, N.A., et al., Greater stimulation of myofibrillar protein synthesis with ingestion of whey protein isolate v. micellar casein at rest and after resistance exercise in elderly men. Br J Nutr., 2012. 108(6): p. 958-62. doi: 10.1017/S0007114511006271. Epub 2012 Jan 31.

4. Apro, W., et al., Leucine does not affect mechanistic target of rapamycin complex 1 assembly but is required for maximal ribosomal protein s6 kinase 1 activity in human skeletal muscle following resistance exercise. FASEB J., 2015. 29(10): p. 4358-73. doi: 10.1096/fj.15-273474. Epub 2015 Jul 13.

5. Sarwar Gilani, G., C. Wu Xiao, and K.A. Cockell, Impact of antinutritional factors in food proteins on the digestibility of protein and the bioavailability of amino acids and on protein quality. Br J Nutr., 2012. 108(Suppl 2): p. S315-32. doi: 10.1017/S0007114512002371.

6. Rutherfurd, S.M. and P.J. Moughan, Available versus digestible dietary amino acids. Br J Nutr., 2012. 108(Suppl 2): p. S298-305. doi: 10.1017/S0007114512002528.

7. Rutherfurd, S.M., et al., Protein digestibility-corrected amino acid scores and digestible indispensable amino acid scores differentially describe protein quality in growing male rats. J Nutr., 2015. 145(2): p. 372-9. doi: 10.3945/jn.114.195438. Epub 2014 Nov 26.

8. Moore, D.R., et al., Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr., 2009. 89(1): p. 161-8. doi: 10.3945/ajcn.2008.26401. Epub 2008 Dec 3.

9. Baier, S.R., et al., MicroRNAs are absorbed in biologically meaningful amounts from nutritionally relevant doses of cow milk and affect gene expression in peripheral blood mononuclear cells, HEK-293 kidney cell cultures, and mouse livers. J Nutr., 2014. 144(10): p. 1495-500. doi: 10.3945/jn.114.196436. Epub 2014 Aug 13.

10. Moore, D.R., et al., Protein Ingestion to Stimulate Myofibrillar Protein Synthesis Requires Greater Relative Protein Intakes in Healthy Older Versus Younger Men. Journals of Gerontology Series a-Biological Sciences and Medical Sciences, 2015. 70(1): p. 57-62.