Protein is a widely researched topic in the sports nutrition world, and beliefs in the general nutrition world differ from the bodybuilding community.
In this article, we will look at the purpose of consuming dietary protein, the role it plays when it comes to physique changes, and the scientific findings on intake recommendations (underconsumption, overconsumption, the whole jazz).
What are Proteins?
Proteins are large molecules composed of one or more chains of amino acids.
Of the 20 amino acids that make up dietary protein, our body cannot produce 9 of them.
This makes it essential that we consume them from our diet, hence they are referred to as Essential amino acids (Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine.)
The rest are Conditionally Essential (amino acids that our body can’t always make as much of in special scenarios when we need it, namely Arginine, Cysteine, Glutamine, Glycine, Proline, Tyrosine), and Nonessential amino acids (amino acids our body can usually make for itself, and do not need supplementation of, namely Alanine, Asparagine, Aspartic acid, Glutamic acid, Serine.)
Why is it important to get enough protein?
Amino acids serve as the basic building blocks of our body.
We need them for countless essential functions like the growth and repair of our body cells and tissue, to make enzymes, hormones, neurotransmitters, and antibodies.
In essence, we cannot function well without adequate protein intake, as basically every body part or tissue requires amino acids.
The total amount of amino acids available to your body for processes like protein synthesis, are housed in an amino-acid pool (kind of like a public swimming pool of amino acids).
When we eat, we break down protein into amino acids, and contribute to the pool.
When our body requires amino acids, it takes it from this pool as well.
Our body cannot store excess protein for use later on, unlike other macronutrients like carbs and fat which have a dedicated storage space, protein stores need to be continually replenished.
This makes it important to consume protein at regular intervals to maximise protein synthesis.
The case for High protein
Usually if someone is looking to increase their skeletal muscle mass, they would enter a controlled phase of overfeeding, caloric surplus.
The goal of such a phase would be to maximize muscle gain while minimising gains in fat mass.
Whereas for someone who wants to lose fat mass, they would enter a cutting phase where calories are by definition restricted below maintenance.
The aim here is to reduce fat mass while maintaining as much skeletal muscle mass as possible.
For both of these scenarios, consuming protein is key, let’s explore the reasons why.
1. Increase in Lean body mass
During periods of calorie restriction, consuming a high protein diet can help preserve lean body mass during weight loss, particularly when combined with resistance exercises.
This is of critical importance because it would mean that more weight loss would come from fat versus lean tissue, in order words there will be an improvement in body composition, not just a drop in scale weight.
This shows that a high protein intake plays a key role in minimising any adverse metabolic changes that occur during diet phases.
For individuals whose goal is muscle gain, high protein intakes also significantly enhance changes in muscle strength and size during prolonged resistance exercise training in healthy adults.
2. Increase Satiation
While physiological, sociological, and psychological factors all influence food intake and hunger.
If you are in a calorie deficit, hunger makes complete sense since you are in a hypo-caloric state.
As researcher Eric Trexler outlines, “at a certain point, the hunger signals will get their point across.
If you’re 6% body-fat and in a big deficit, making the last push to the bodybuilding stage, no dietary tricks are going to entirely blunt hunger.
However, if you’re trying to arrange a diet to manage hunger as effectively as possible, there are many tools to use, and protein is just one of them.”
Satiation which describes the lack of desire to continue eating a meal, tends to increase in line with protein intake.
This is particularly true where 25-81% of a meal’s calories came from protein.
In other words, greater satiety was experienced with higher protein meals.
This makes the whole cutting phase especially more tolerable by lengthening the time that your diet does not feel like a diet per say.
Higher protein foods tend also not to be very calorie dense, and they can be quite voluminous.
Ever try to eat 500kcal worth of chicken breast at one go?
That’s about 450g of chicken meat. Good luck with that!
That said, when it comes to satiation, we need to look at the foods and meals on a whole, rather than individual nutrients or ingredients.
If you struggle with hunger, you should intentionally avoid hyperpalatable foods that are easy to overeat, calorie dense and usually low on nutrients.
Instead, try to have meals with high protein, fiber, water content, low calorie density, and plenty of unprocessed or minimally processed foods.
3. Higher Thermic Effect of Food
Protein also has a higher thermic effect of food (TEF) at about 25-30%, compared to carbs which has a TEF of 6-8%, and fats TEF of 2-3%.
What this means is that while your body is taking energy in when it’s consuming protein, about a fifth to a third of that is used up to digest, absorb and process the nutrients in protein itself, resulting in a transient increase in energy expenditure.
The impact of any increase in TEF remains limited, given that TEF makes up only about 10% of TDEE.
Hence while increasing total TEF through protein intake may affect your body composition, the effects are likely seen greater over the longer term.
4. Harder to store as Body Fat
Interestingly, when controlling for calories, it is far more difficult for your body to store protein as body fat, compared to carbs and fat.
Looking at this study in detail, subjects were force fed 140% of their maintenance calories for 8 weeks straight, and split into 3 separate groups: low protein (5% of total calories/ average 47g @ 0.30g/lb), normal protein (15%, average 140g @ 0.81g/lb), or high protein (25%, average 230g @ 1.36g/lb).
At the end of the study, all subjects gained identical increases in body fat, while the normal and high protein group put on an additional 3kg of body weight, but much more of that consisted of lean muscle mass and not body fat.
To quote the authors of the study, “Calories alone contributed to the increase in body fat.
In contrast, protein contributed to changes in lean body mass, but not to the increase in body fat."
This does not in any way override the energy balance equation, as it can be seen that body mass increased in all groups as all groups were operating at a caloric surplus.
However it shows that even while eating 1000kcal more than necessary to maintain body weight for 8 full weeks, higher protein intake contributed to greater increases in lean body mass rather than body fat.
How much protein do you need?
So what is an appropriate number to shoot for?
As with everything else, it’s important to always look at multiple factors (activity level, training volume, caloric state, current body composition, age, disease or illness, genetics etc) to appropriately individualise numbers- the most important being activity level.
There has been much debate suggesting that the Recommended Dietary Allowance (RDA) for protein of 0.8g/kg (0.36g/lb) body weight is inadequate to promote muscle gain.
To be clear, consuming per RDA recommendation may in fact be sufficient, but only in untrained, generally healthy adults to prevent protein deficiency.
For basic protein synthesis, you generally don’t need to consume more than 0.6-0.9/lb of protein per day.
However, if your goal is body composition changes, and in order fully reap the benefits of higher TEF, increased satiation and promote adequate recovery between hard training sessions, daily protein intake of between 1.0-1.4g/lb of bodyweight is recommended.
Is there such a thing as too much protein?
You may have heard the claim that excessive protein intake can harm the kidneys, liver and even bone density.
However, there is insufficient direct evidence to support this.
In fact, tracing back the origin of this claim, we find that it was first made after a trial found that rats with one kidney following a high protein diet experienced renal hypertrophy or damage.
This underscores the point that it is critical to consider the magnitude of the protein intake and health status of the individual in question.
For persons with an existing kidney disease or damage, reducing protein intake can improve markers of kidney function.
Whereas for the average healthy person, a high protein diet above 1g/lb (2.2g/kg) of bodyweight has not shown negative effects on kidney or liver health, even over the span of multiple years.
Protein alone is not enough
There are always going to be reasons that may prevent us from training temporarily, whether we’re travelling, injured, or just super busy.
Increasing protein intake during such periods have been usually used by lifters in an attempt to minimize any potential losses of muscle mass or strength that they have trained so hard to build up.
Unfortunately, high-protein diets don’t appear to reduce drops in muscle size and function during detraining.
Exercise is the primary stimulus with the greatest impact.
Luckily, we are able to maintain training adaptation with surprisingly low training volume, as long as intensity is kept high.
Thus even if you are unable to train with heavy loads, it would be more strategic for you to maintain some training stimulus rather than rely on increasing dietary protein intake.
A step further
When you eat protein matters too.
That’s right, the timing and distribution of protein consumption throughout daily meals may be as important as the total quantity to stimulate muscle protein synthesis and the maintenance of muscle mass and function.
Research recommends evenly distributing daily protein intake between meals every 3-5 hours to maximise hypertrophy.
While consuming protein around training when intake is at 1.8-2.7g/kg per day of protein likely has a trivial impact on untrained individuals when not in an energy deficit.
It is possible that trained individuals and/or dieting individuals would benefit from consuming protein 1-2 hours before and after training to preserve LBM, strength, and muscular endurance while dieting (~0.4-0.5g/kg is a reasonable recommendation).
Summary
Protein is essential to our survival.
We cannot store excess protein in our body, so we need to ensure continual consumption.
Protein intake is highly beneficial for individuals concerned with body composition goals as it helps to increase lean body mass, satiation, thermic effect of food, and because it is simply harder for the body to store excess protein as body fat compared to carbs and fat.
There are further nuances when it comes to daily recommended intake such as meal composition, timing, amino acid profile, but ensuring a high protein intake alongside strength training are two key aspects of long-term body composition changes.