By Paul Stevenson
In the first of this 3-part series macronutrients 101, I want to study the macronutrient protein, assessing the role is has in the body, what foods it can be found in, and recommended daily intakes. At the Clean Health Fitness Institute, all of our personal trainers undergo extensive nutrition and diet study with our CHFI Performance Nutrition Coach Certification which we teach to coaches around the world.
Now the reason protein is the macronutrient first to be featured is because it is widely recognized as the most important of the 3 macronutrients. Indeed the word ‘protein’ comes from the Greek word ‘proteos’ meaning ‘primary’ or ‘taking first place’. Around 40% of protein in the body made up of muscle tissue, around 25% made up of organs, with the rest found mostly in skin and blood (Gropper & Smith, 2012).
Protein is made up of amino acids. Amino acids have been classified as either ‘essential’ or ‘non-essential’ based on whether the body can make the amino acid for itself (non-essential), or whether it must be derived from one’s diet (essential). There are considered to be 9 essential amino acids that the body is unable to produce itself and therefore must come from the diet.
The main dietary sources of protein come from:
- Animal Sources: Meat, poultry, fish, eggs and dairy products
- Plant Sources: Grains, legumes, vegetables
Generally-speaking animal sources are viewed as ‘high-quality’ or ‘complete’ sources of protein as they contain all the essential amino acids needed by humans. Most plant sources of protein are known as ‘low quality’ or ‘incomplete’ proteins as they lack one or more of the essential amino acids. This is why vegetarian and vegan diets need to be carefully planned to ensure that all essential amino acids are derived from the diet. For example, legumes are often consumed with grains as their amino acid combinations are complementary.
How Much Protein Do I Need?
- Recommended Intakes for strength training individuals is 6-1.8g per kg of bodyweight. Therefore for an 80kg person this relates to a daily intake of between 128g-144g of protein per day. There is no research to suggest more muscle can be built with intakes higher than 1.8g/kg. For example, Hoffman et al (2006) found no support for protein intakes greater than 1.6-1.8g/kg in collegiate strength & power athletes for altering body composition.
- Instances where it can be argued that a slightly higher intake may be optimal is in the case of beginner trainees embarking on strength training. In this scenario you could bring intakes up to 0g/kg of bodyweight. This is because beginners can expect to build large amounts of muscle mass when embarking on a strength training program.
- Vegetarians will generally need an intake of 4g/kg of protein per day. This is due to the lower quality of plant-based protein which means less of the protein is absorbed by the body.
- For the average gym goer who is not looking to maximize muscle mass and just wants to lose a little weight, intakes of 2g/kg-1.4g/kg will be more than sufficient in maintain lean mass whilst losing body fat.
So as you can see from the above, intakes are case dependent, and will vary depending on a client’s goals.
Benefits of Higher Protein Intakes
To the general population, these intakes are often higher than they are accustomed to. However, the reason why we at the Clean Health Fitness Institute use these levels are for the following reasons:
- Enhanced Muscle Building: An insufficient protein intake will impair someone’s ability to build muscle. This is bad news whether your goals are to build muscle or lose fat because having more lean muscle mass is important to both processes.
- Higher Thermic Effect of Food (TEF): The thermic effect of food relates to the amount of energy required to digest and absorb food. Of the 3 macronutrients, protein has the highest TEF. In practical terms this means that your body will expend more energy digesting and absorbing a high protein diet than a low protein diet, aiding in fat loss.
- Satiety: Protein is also the most satiating of the 3 macronutrients. This is excellent news for anyone wanting to lose fat, as having a high protein diet will keep them feeling fuller for longer, reducing the chance of snacking and over-eating.
- Reduced Chance of Sarcopenia: Sarcopenia is the involuntary loss of muscle mass with age, and affects up to 25% of older adults (Gregorio, et al, 2014). Women in this study who protein intakes below 1.1g/kg had higher body fat and fat-to-lean ratios than those who consumed a higher protein intake. Higher protein intakes can offset the loss of muscle mass with ageing, which is vital to health and well-being in the older populations.
Now we know how much protein we should be consuming it is important to consider how the protein should be distributed across the day. Traditional dietary patterns generally has protein intakes skewed towards the end of the day, with a small intake at breakfast which is usually more carb-heavy, a moderate amount at lunch and a larger bolus dose of protein with the evening meal.
However for the stimulation of muscle growth a more even distribution across all meals is more effective (Mamerow, et al, 2014). This is because the body has a limited capacity to store excess protein from a single meal and acutely stimulate muscle growth at a later time, it is better to take more of an even distribution across meals throughout the day. For example, a 90g serving of protein has no greater effect on muscle protein synthesis than a more modest 30g serving.
Leucine is one of the 9 essential amino acids, and is particularly important for us to consider as it stimulates mTor, which is highly important for muscle growth (Norton & Layman, 2006). To optimize muscle growth the total daily intake of protein is vital, but so too is the optimal intake of leucine. It is fairly easy to ensure you consume enough leucine if you follow the recommended intakes in this article and you consume a complete source protein with each meal.
To ensure you meet your leucine requirements you should consume 3g/kg of protein from a complete source in each meal. So for an 80kg individual this equates to 24g per meal. Reaching the leucine threshold in every meal is another reason why a more even distribution of protein is better than a skewed distribution as the meals with only small amounts of protein may not reach the leucine threshold and as a result will not stimulate muscle protein synthesis.
Take Home Points
- Protein intake may vary slightly, but generally speaking for most strength trainees, an intake of 1.6-1.8g/kg is the recommended daily intake
- Higher protein diets are beneficial for increasing muscle mass, increasing the TEF and Increasing satiety
- Protein intakes should be evenly distributed across all meals of the day
- Gropper, S, Smith, J, “Advanced Nutrition and Human Metabolism”, 2012.
- Hoffman, J, et al, “Effect of Protein Intake on Strength, Body Composition and Endocrine Changes in Strength/Power Athletes”, Journal of the International Society of Sports Nutrition, 2006.
- Gregorio, L, et al, “Adequate Dietary Protein is Associated with Better Physical Performance Among Post-Menopausal Women 60-90 Years”, Journal of Nutrition, Health and Ageing, 2014.
- Mamerow, M, et al, “Dietary Protein Distribution Positively Influences 24-H Muscle Protein Synthesis in Healthy Adults”, Journal of Nutrition, 2014.
- Norton, L & Layman, D, “Leucine Regulates Translation Initiation of Protein Synthesis in Skeletal Muscle After Exercise”, The Journal of Nutrition, 2006.