How much protein do you really need?


Emma Thornton
Qualified Nutritionist (ANutr)
@EmmaThornton
Ask Emma


12 June 2018

Why is protein so important?

Protein is definitely becoming a buzzword when it comes to nutrition and health, evolving from its position in the world of sport and weight-lifting and, while I couldn’t be happier with this shift in attitude, it does present a noticeable problem.

Firstly, muscle-building aside, not many of us seem to actually know much about how our body uses protein. There’s a reason that proteins are known as the ‘building blocks of your body’ but let’s start with what proteins actually are. 

At their core, proteins are complex molecules formed of hundreds or thousands of smaller building blocks called amino acids. Around 20 amino acids in total are needed to form a protein molecule and the combination that they are arranged in usually dictates their function. 

Unsurprisingly, proteins are recyclable – after all, how else would you be able to get protein from your diet? Plants and animals are formed of proteins too and when we eat them, they get broken down in our bodies back into amino acids, which we can then form into different combinations to create new proteins.

It’s thought that there are around 8 different types of protein which can each serve a variety of functions within the body. 

  • Hormonal
  • Enzymatic
  • Structural 
  • Defensive
  • Storage
  • Transport Motor

How does your body use proteins?

Your body can use protein in a surprising amount of ways. Of course, protein’s more famous role is arguably related to your muscles. When you consume protein, it ultimately ends up in your digestive tract, where is broken apart into chains of amino acids, known as ‘peptides.’

Your body then uses peptides to restore and rebuild muscle fibres. This is particularly important when it comes to fitness, especially a form of training known as ‘resistance training.’ In order to grow, your muscles need to repair small micro-tears, which is where peptides come into the picture and part of the reason why protein is so sought after. 

However, protein is also extremely important for your immune system. You may have heard of antibodies, which are actually defensive proteins, and help to target invading pathogens and bacteria, with a little help from antigens

So you need a decent amount of protein in your diet to keep your immune system ticking but what about haemoglobin? As the name may suggest, haemoglobin is formed by a haem (group) which contains iron and a globular transport protein. A key component of healthy red blood cells, haemoglobin helps to transport oxygen around your body and move carbon dioxide back into the tissue of the lungs. 

It would also be remiss of me to mention protein without talking about your skin. It’s estimated that around 42% of our dry body weight is composed of proteins and a good portion of this would be collagen.1 Collagen is the most abundantly found protein in your body and is a part of all your connective tissues. It’s a key structural protein when it comes to your skin alongside keratin, a fibrous protein that is an essential component of your skin, hair and nails.

So, it should go without saying that you need protein to survive but what happens if you’re not getting enough?

What happens if you don’t get enough protein?

Protein is absolutely essential so a lot can go wrong if you’re not getting enough of it. Below I’ve listed just a few of the minor symptoms you may experience if you’re deficient in protein but I will move on to explain the more drastic side-effects.

  • Fatigue
  • Cravings
  • Thinning hair
  • Irritable skin
  • Mood swings
  • Poor sleep
  • Difficulty concentrating

These symptoms can be quite commonplace and easy to attach to other conditions, but it is still important you investigate them. 

What is the recommended daily amount of protein?

According to most experts, protein should make up between 20-35% of your calorific intake but how much is this in terms of grams? Well gender does play a role so often men are advised to get a little bit more protein than women but, according to government guidelines, around 45g for women a day and 55.5g for men should suffice.2 

This might not sound like a lot, particularly if you’re used to being confronted with the idea that you should be getting over a 100g a day, but remember, this figure is for sedentary adults between the ages of 19-64. Not to mention, this figure can vary from person to person depending on your individual needs.

Another way of deciding your protein intake could be to subscribe to the idea of consuming 0.8g of protein per kg of weight. In accordance to these guidelines, an 11 stone woman would need to eat around 53g of protein a day. 

Again, this method isn’t perfect so it’s best to try and opt for a middle ground. If you are a woman, you should be aiming for between 45g and 50g of protein a day while a safe guideline for men should be between 54g and 60g of protein. 

What if I am trying to build muscle mass?

Obviously, if you are trying to build muscle mass, your daily recommendations will change but why is this? 

As I mentioned earlier, when you exercise you’re actually damaging your muscles fibres, which despite sounding quite serious, is necessary for muscle growth. Since protein is needed to repair your muscles, your body will signal for protein molecules to help mend the damage. In the process of mending your muscle fibres, these protein molecules sometimes provide extra muscle mass.

This can be a slow cycle to start with and your muscles have to synthesise protein more quickly than they break down in order for the process to work correctly. This is why body builders frequently try to increase their protein intake via shakes, energy bars and other supplements. 

Make no mistake though, protein on its own is not going to give you bulging biceps. So how much protein should you be getting if you’re exercising regularly? The International Society of Sports Nutrition seem to think that anything between 1.4g-2g of protein per kg should be sufficient, depending on the type of exercise you are involved in – for example, endurance athletes may be at the lower end of this spectrum compared to those that are involved with strength training.3  

This means that if you are training for a marathon and weigh around 180kg (12st 8), you should be consuming around 112-160g of protein a day. 

What if I’m trying to lose weight?

Protein and weight-loss can really be a divisive issue.  Whereas before low fat diets were all the rage, now protein is being brought to the forefront and there is a good reason for this. 

One study, conducted in 2012, put overweight patients on a calorie restricted diet, with one group abiding to the recommended protein guidelines while the others consumed 1.6g of protein per kg of body weight. The results found that those on the higher intake of protein ultimately lost more weight than those on the recommended daily amount.4 

It’s important to realise though, that these participants were limited to 500 calories a day, quite a drastic restriction considering you should be getting between 2000-2500 calories a day, depending on your gender! However protein can be effective as a weight loss aid as it takes longer to digest than carbohydrates, helping you to stay fuller for longer. 

If you are attempting to lose weight, I would recommend first cutting back on processed fats, refined sugars and simple carbohydrates. Then you can look into increasing your protein intake – between 1.2-1.4g of protein per kg of body weight  or between 70-100g depending on your body weight, might be a healthy goal to start with as getting too much protein can sometimes be just as serious as not getting enough! 

Who else might need more protein?

Over 50’s

So apart from gaining muscle mass and losing weight, who else might want to consider increasing their protein intake? Surprisingly, there are quite a few groups that might benefit from a little extra protein in their diets and one is those who are over the age of 50.

As you age, unfortunately you will start to lose muscle mass and definition, which is sometimes known as sarcopenia and can even be connected to low bone density and insulin resistance. However, a study published in the American Journal of Physiology – Endocrinology and Metabolism, demonstrated the positive impact of increasing your protein intake. 

In this study, four meal plans were assigned to subjects between the age of 52 and 75. After just 4 days, it was shown that those who ate more protein were better at building muscle and synthesising protein.5   

Menopausal women

As our menopause expert Eileen details in her blog ‘How much protein do we really need during menopause’, protein can be a valuable addition to the diet of menopausal women. Protein is essential for the digestive and nervous systems and even our hormones, all of which can be impacted during the menopause. 

If you’re not getting enough protein, this can affect your falling oestrogen levels and make it difficult for your body to produce sex hormones. It can also influence your digestive system and make it difficult to break down your food, meaning you’re not absorbing the nutrients that you should be. 

Vegans and vegetarians

Vegans and vegetarians are naturally a bit more at risk of low protein due to their diet restrictions. Since high levels of protein are usually found in meat and dairy products, vegans and vegetarians may have to go that extra mile to boost their intake, turning to beans, legumes, lentils, tofu and sometimes protein powders.

1http://learn.genetics.utah.edu/content/basics/proteins/

2https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/618167/government_dietary_recommendations.pdf

3https://jissn.biomedcentral.com/articles/10.1186/s12970-017-0177-8

4https://www.ncbi.nlm.nih.gov/pubmed/22691622

5http://ajpendo.physiology.org/content/308/1/E21

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