Protein is the macronutrient du jour, with an ever increasing range of products on the shelves with extra protein added or their protein content highlighted and promoted for marketing purposes.
Protein chocolate spread, protein cookies, protein drinks, protein powders, balls, bars, flapjacks – the list is growing; even big-name chocolate bar manufacturers are doing a ‘protein’ version of their old classics.
Riding a bandwagon these brands may be, but what benefit is all that extra, added protein really giving you, the consumer?
What is protein?
Let’s start by looking at protein itself – when people use the word protein in reference to working out and/or health & fitness in general, they refer to it as a singular substance that we must get more of in order to help build and repair our muscles.
However, proteins come in various shapes and sizes and are constructed from building blocks called amino acids, of which there are 20, with some being made by the body itself and others coming from our diet.
We need the full compliment in order to maintain optimum health – creating proteins to build muscle, repair tissue, produce enzymes and hormones, transporting nutrients and resisting diseases.
Protein provides the body with around 10-15% of its dietary energy (at 4kcal per gram, protein delivers us the same energy as carbohydrate) and it’s the second most abundant compound in the body, after water.
A large proportion of this protein will be muscle (approx 43%) with significant proportions being present in skin (approx 15%) and blood (approx 16%) 1.
As mentioned, your body requires 20 amino acids in order to create and utilise the proteins that are vital to its proper functioning. Out of these 20 amino acids, the body can synthesise 11 with the remaining nine having to be obtained from dietary sources of protein.
Dietary sources of protein are of two types, ‘complete’ and ‘incomplete’. Complete proteins contain all of the amino acids the body requires to function correctly, whereas incomplete proteins are low in some of these essential amino acids.
Essential amino acids: Histidine, Leucine, Isoleucine, Lysine, Methionine, Phenylalanine, Valine, Tryptophan, Threonine.
Synthesised amino acids: Alanine, Glycine, Proline, Arginine, Serine, Asparagine, Tryosine, Aspartic acid, Cysteine, Glutamic acid, Glutamine.
Animal protein sources are considered to be ‘complete’ proteins as they are high in essential amino acids and include such things as red and white meats, seafood, dairy products and eggs.
Plant protein sources – such as fruits and vegetables, nuts, seeds, beans and pulses – can be low in some essential amino acids and are therefore considered ‘incomplete’ proteins.
For individuals following vegetarian and vegan diets the key is to consume a wide variety of plant-based foods, as amino acids that are lacking in one food will be present in another.
With some simple planning and by combining food groups, you can easily meet protein requirements and consume the full range of essential amino acids.
How much protein do I need?
So, how much protein do you really need to be consuming? The recommended allowance for protein in order to maintain health is 0.75g per kg of bodyweight (bw) per day for both sexes (Calloway and Kurzer, 1982), (WHO, 1985).
N.B. this figure varies, dependent on source, with some bodies giving figures of 0.8g per kg/bw and 1g per kg/bw.
Therefore an individual weighing 57.5kg (9st) would require 43g of dietary protein per day.
In those undertaking exercise programmes, protein requirements can be higher, with experienced, well-trained individuals, such as athletes or bodybuilders wanting to gain further muscle mass, potentially requiring up to 2g per kg/bw per day.
For example, an individual undertaking a muscular hypertrophy (body building) program weighing 89kg (14st) could require up to 178g of dietary protein per day.
Protein intake also needs to increase as we age and at around 50 years we need to increase the protein in our diets to 1g per kg/bw in order to maintain muscle mass.
For expecting mothers it’s recommended that throughout pregnancy an additional allowance of 10g of protein per day is consumed to allow for the greater nutritional requirements imposed by gestation (WHO, 1985).
Am I getting enough protein?
The answer to that is ‘most probably’, but let’s look at an example for reference purposes. Below is the protein intake a hypothetical office worker might get from three average meals during their working day – remember this doesn’t include any additional snacks, drinks or nibbles.
Breakfast: Porridge with semi-skimmed milk: 27g oats = 10g protein
Latte (medium): 355ml = 10g protein
= 20g protein
Lunch: Tuna mayo & sweetcorn sandwich: 170g = 21g protein
Braeburn apple: 131g = 1g protein
Crisps: 50g = 3g protein
Orange juice: 250ml = 2g protein
= 27g protein
Dinner: Spaghetti bolognese: spaghetti 180g, bolognese 270g (450g) = 22g protein
Salad: 60g = 1g protein
Cheesecake: 150g = 6g protein
Tea with milk: 260ml = 1g protein
= 30g protein
Daily total dietary protein intake = 77 grams (308kcal) 2
Protein: 77g intake ÷ 0.75g requirement = 102.6kg bodyweight
From this we can see that enough protein has been consumed for an approx 102kg (16st) individual.
Assuming this diet was balanced correctly in terms of macronutrients (see below), it would cause someone with a mass of <102.6kg to gain weight as the human body does not store excess protein, while some is converted to urea and passed in the urine, the excess energy from the protein is stored on the body as fat.
While we may be consuming more protein than ever before (on average, protein provides around 16-17% 3 of the energy in a British diet), for optimal macronutrient balance, protein should only make up 10-15% 4.
UK Government guidelines, percentage proportion of dietary macronutrients for optimal health:
- Carbohydrate: 50-55%
- Fat: 30-35%
- Protein: 10-15%
It is also important to remember that if you are sticking to a calorie-controlled diet, but you are consuming more protein than your body requires, then it is likely you are not getting enough carbohydrates or fat for your body to function properly and this will therefore inhibit exercise performance and development.
Do protein needs increase if you are very active?
The short answer is yes. There is plenty of evidence to suggest that individuals involved in resistance training to increase muscle mass may benefit from protein intakes as high as 2g per kg/bw per day 5, with the general sports-science consensus being that endurance athletes (those who regularly participate in activities like running, cycling, or swimming) consume >1g of protein per kg/bw per day and strength-training athletes (powerlifting or weight training on a regular basis) should consume >1.5g of protein per kg/bw per day.
Intense or prolonged exercise causes an increase in muscle protein breakdown, followed by an increase in muscle protein synthesis over the next 24 hours. Consuming protein during this period accelerates the recovery process and stimulates muscle growth.
It has been shown that additional dietary protein, post-exercise, can aid recovery 6, with the recommended amounts increasing as the duration of exercise increases. For exercise lasting 90-120 minutes, add 0.275g per kg/bw afterwards. For exercise lasting 120-240+ minutes, add 0.3g per kg/bw.
Let’s look at an example, in food terms, to see how a hypothetical individual could meet their protein requirements – as we are focusing on protein only, we will not go into the fat/carbohydrate levels in the food here:
An 89kg (14st) person undertaking a weight training programme and looking to gain muscle mass is aiming to consume 1.5g protein per kg/bw per day = a total of 133.5g.
Breakfast: Beans on toast: 2x slices of bread 70g, can of beans 400g, butter 10g = 26g protein
Banana: 130g = 2g protein
Cappuccino (large): 475ml = 8g protein
= 36g protein
Lunch: Salmon frittata: 290g = 37g protein
Greek Salad: 140g = 4g protein
Pumpkin seeds: 30g = 7g protein
Semi-skimmed milk: 568ml (pint) = 20g protein
= 68g protein
Dinner: Pasta bake: tuna, sweetcorn, cheese 426g = 32g protein
Water: 568ml (pint) = 0g protein
= 32g protein
Daily total dietary protein intake = 136 grams (544kcal) 6
He we can see that the individual’s weight training protein requirements are already met by a sufficiently balanced diet.
Highly active people like sportspeople and regular exercisers, who have higher than average energy intakes, normally have higher than average protein intakes simply from the amount and types of food they eat, so for most people, if their energy intake is sufficient, their protein intake will also be sufficient.
Most protein bars contain around 20-25g of protein and around 300-400kcal of energy. While some are made from natural ingredients, many also contain hidden sugars and/or artificial sweeteners, which not only give you unnecessary calories but can lead to an increased craving for sweet foods. Always read the label.
Many protein snacks are also ‘boosted’ with multivitamins and other minerals, which again, if you are eating a sufficiently balanced diet, are unnecessary and it is always better to get your protein from natural foods rather than supplements – because real food contains a lot of other supporting nutritional extras such as vitamins, minerals and fibre.
Here’s some easy, high protein, quick-snack alternatives with calorie counts:
Pint of skimmed milk (568ml) = 20g protein / 193kcal
Natural yoghurt, low fat (250g) = 12g protein / 143kcal
Greek yoghurt, low fat (250g) = 18g protein / 192kcal
Skyr Icelandic yoghurt (250g) = 30g protein / 170kcal
Beef jerky (60g) = 30g protein / 232kcal
Soya nuts (60g) = 22g protein / 244kcal
Boiled eggs x 3 (180g) = 24g protein / 237kcal 7
So, while protein bars and their ilk certainly do have their place for a low-calorie, high-protein hit; if you feel like grabbing a protein bar or similarly protein-enhanced snack after your workout then just remember that, if your average day includes a sufficient number of well-balanced meals, then any additional protein is potentially being stored on your body as fat, not muscle.