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Protein. You don't seem to eat enough of it. Your coach tells you to eat more of it. You don't even really know what it is?!
In this post we are going to discuss why the only thing your nutrition coach waffles on about is protein. Answering the questions, what is protein, why do I need protein and what are the best sources of protein?
What is protein?
Proteins are large biomolecules made from chains of amino acids. Dietary proteins are essential macronutrients, meaning they are required in large amounts in the body. In this post we are going to be discussing the importance of protein for muscle growth, but even if your goal isn't to build muscle, protein should be an essential goal in your dietary goals because they are responsible for the function of major systems in the body like the immune, digestive and hormonal systems. Think of protein as the parts that make up a car. It's all well and good having a tank full of petrol, but without the wheels, the engine, the steering wheel, your car won't even exist, let alone work!!
When discussing protein for muscle growth, it is important to understand amino acids. Think of a protein molecule as a metal chain. Each link in the chain is an individual amino acid and the amino acids link together to make long chains, called proteins. One 'chain' (protein) can be anywhere form 10 to 27,000 'links' (amino acids) long. There are about 20 different types of 'links' that make up the 'chains'. Our bodies are clever enough to synthesis most of these on it's own, but there are 9 of these 'links' that our bodies cannot create, which is why we need to get them through our diet. These are called the 9 essential amino acids because it is essential we consume them in our diet.
Animal vs Plant protein
A debate around animal vs plant protein is an important one to consider, especially if you are a vegan or vegetarian. There is a key difference between the two sources of protein, and understanding essential amino acids is necessary to understand this. Previously, it was said that plant proteins don't contain all 9 essential amino acids, unlike animal proteins. But now it is understood that whilst plant proteins do contain all 9 amino acids, they do not have the optimal percentage of amino acids that the human body requires. For example, leucine is the name of an amino acids that is considered the most important for muscle growth. Compared to animal protein, plant protein contains a significantly lower amount of leucine, meaning it is not as effective for muscle growth.
We analysed modern studies on the difference between animal and plant protein and there effect on muscle growth, and drew a reasonable conclusion to help you understand the difference.
A 2023 study reviewed the effects of an omnivorous diet and vegan diet on skeletal-muscle growth. The study reviewed muscle adaptation in 38 individuals over a 10 week period, with one group strictly following an omnivore diet, the other following a vegan diet. The conclusion from the study showed comparative results between the two groups, meaning there wasn't a major difference in skeletal muscle adaptations between the two groups. This shows that muscle growth can be stimulated following a vegan diet.
To supply more evidence, we analysed a 2021 meta-analysis on animal vs plant protein for lean mass and muscular strength. The article reviewed 18 studies, and showed that for total lean mass, once again, there wasn't a comparable defence between plant and animal protein. However, absolute percent lean mass was higher in groups who ate animal protein rather than plant. The article concluded animal protein was better for lean mass adaptations, especially in younger (<50) individuals.
What is bioavailability?
So now we understand the difference between animal and plant protein, it is time to discuss bioavailability. Bioavailability means, of the total amount of protein available, how much can our body absorb and use. So why is this important? Well, as is with the idea of calories, just because a food source contains 100g of protein, it doesn't mean our body will be able to digest and absorb that full 100g. 9 times out of 10, your body will digest most of the protein in a food, but to optimise muscle growth and protein intake, we should be trying to consume highly bioavailable sources of protein.
The top 6 bioavailable sources of protein...
Whey protein - Whey protein is the most bioavailable source of protein. It absorbs quickly, at an estimated rate of 10g per hour.
Eggs (Egg whites) - Eggs were once thought to be the most bioavailable source of protein at an absorption rate of 3g per hour
Cows milk (un-processed)
Fish
Beef
Chicken
A myth around protein is that if you eat more than 30g of protein in one sitting, your body will just get rid of the rest. This is not true. Your body absorbs protein at an average rate of 10g per hour. So if you eat 30g of protein, it will take you 3 hours to digest it. If you eat more than this, your body won't just get rid of it, it will just take longer to digest.
So does this mean whey protein is the best?
The best source of protein
Amino acid distribution and bioavailability tell us that whey protein is the best source of protein, so should you just drink protein shakes instead of eating eggs, chicken or other protein sources every day?
Well, our diet is not just about protein, carbs and fat, we also need to manage out micronutrients. This includes all vitamins and minerals. Luckily, for most of us without a deficiency, we don't need to worry too much about this because a regular balanced diet will provide sufficient micronutrients to the body. So when we consider micronutrients, and overall nutrient density of whey protein, it becomes one of the worst sources of protein. Sources like chicken, eggs and especially plant proteins are dense in micronutrients, where whey protein is simply a supplement that just provides protein.
So we recommend, for an optimal protein diet, have one scoop of whey protein a day, plus one source of the most bioavailable protein listed above at least once in every meal.
A diet high in protein will contain these sources as a minimum during the day...
Breakfast - 2-3 eggs
Lunch - 100-150g chicken breast
Snack - 1 scoop whey protein
Dinner - 100-120g fish/beef
How much protein do I need?
Now we know why we need protein and where to get it from, how much do you need? The UK government recommendation is a minimum of 0.8g/KG/day. However, recent studies have shown this to be less than half of what you should realistically be aiming for. We recommend
1.6 - 2.2g/KG/day depending on your current activity and fitness goals.
Protein calculation for inactive individuals - 1.6 x bodyweight (kg) = protein (g)
Protein calculation for active individuals - 2.2 x bodyweight (kg) = protein (g)
A 2018 article on protein absorption recommends that you split this up into 4 meals of 0.4g/kg/meal or 0.55g/kg/ meal for optimal protein absorption.
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