Protein Requirements

Protein – and No BroScience


One of the biggest issues nutritionists, particularly sports nutritionists, face is the problem of broscience – the passing on of advice from one man to another with little or no scientific foundation. Protein requirements has to be in the top 5!

I’ve read a lot of blog articles and articles online, so many written by well-meaning people wishing to pass on the knowledge they have accumulated. Nutrition very often falls into this massive well of some knowledge, but not enough knowledge.

For me, one of the biggest obstacles in nutrition science is broscience – the passing on of rogue information from one man to the next, typically in the gym. This creates a cascade of false information.

Furthermore, I’ve often heard that we’re not getting enough protein – is this really true?

This blog post is intended to start thinking and talking about protein for men. Why men? Whilst not exclusively so, men are more likely to overconsume protein than women.

In fact, if you look at the marketing of protein products, they do appear to have a male-centric marketing strategy. Although, women will get something from this post too.

In later posts, we’ll make reference to this and start looking at protein for weight loss or weight gain and recovery.

What is protein?

If you go to the gym, or have a personal trainer, you might often hear the term “macros”. This is a shortened version of macronutrients, nutrients we require in bulk, which include fats, carbohydrates and proteins.

Of the three macronutrients, you might be surprised to hear that protein is actually required in the smallest amount. We do not need anywhere near as much as many people seem to think.

Protein is the building block of all the tissues in the body. When we consume protein, our digestive system breaks it down into its component amino acids. Each amino acid has specific functions in the body, including making other amino acids.

Some amino acids, however, cannot be made by us and we must get them in the diet. These are known as essential amino acids.

We’ll talk about individual amino acids in other posts, for example – you might remember the post that looked at the roles of tryptophan and tyrosine in the manufacture of hormones and neurotransmitters when we discussed mental health.

Complete vs. incomplete proteins

You may have heard the expression complete proteins – particularly when people talk about plant-based diets. It simply means that a particular food source contains all the essential amino acids in a perfect ratio.

Remember, many amino acids can convert to other amino acids in the body, but essential amino acids are always required from the diet.

All animal-based protein (meat, fish, dairy and eggs) are complete proteins, but not many plant-based are. There are a very few exceptions: soya, quinoa are two that spring to mind, but most require clever combinations to ensure all the essential amino acids are consumed.

Role of protein

Now we know what it is, but why do we need protein? We all know we need to get enough of it – many vegans and vegetarians are often asked so where do you get your protein? But protein is ubiquitous, albeit in variant quantities and quality.

The three major sources of protein in the body are muscle tissue, blood plasma (the thin liquid that carries blood cells and other structures) and organ tissue.

Tissues turnover all the time, and so we need protein to replace them. Around 15% of our entire body mass is made up of protein (a lot of our body mass is just water!), and similarly around 15% of our dietary requirements are protein.

Individual amino acids within proteins go on to make various essential compounds such as enzymes, hormones, neurotransmitters. DNA is made up of base pairs, which themselves are amino acids called nucleobases.

Blood contains proteins necessary for clotting, and all the collagen containing structures of the body are made from proteins: hair, nails, skin, bones, ligaments, tendons and other structures around the body that anchor our organs in place.

How much do we need?

The average human being only requires around 0.8g of protein for each kilogramme of body weight.

You would think that with so many diverse roles of protein, we’d need a lot to keep us functioning. But actually, protein provides the smallest contribution of all our macronutrients. We need around three-times more carbohydrates than we do protein!

Typically, people who follow low carbohydrate diets such as the keto diet will significantly increase their protein intake – and we need to examine the safety of this.

When protein is broken down, it creates new proteins but only what the body needs at the point the protein is ingested. The rest is then split into two routes: the nitrogen element of the protein is excreted into the urine (or sweat).

The remainder converts to energy, because protein can not be stored like fat (in fat cells) and carbohydrates (glycogen). If you eat too much of them, then the body simply converts them into energy through oxidisation, and if it has enough of that, then converts to body fat where energy is stored for later.

The process where proteins are broken down and built back up again is known as protein turnover – the created balance between the amount of protein we make and the amount that is degraded.

If we excrete less nitrogen in our urine than we consume as protein, we are said to be in positive nitrogen balance. If we excrete more nitrogen than we consume in protein, then we’re in negative nitrogen balance.

We want to be in perfect nitrogen balance – that is to consume the same amount of nitrogen as we’re excreting. Then we know that all the protein we’re eating is being used as we want it to be, and not converted to energy.

Problems of being nitrogen negative

If we’re in negative nitrogen balance, there’s a risk that our muscles are being degraded for protein – we definitely do not want that. This can happen even when we consume more protein than we need. It’s common for people who follow a low carbohydrate diet.

Intense exercise, illness, dieting can all contribute to a nitrogen negative state. So our nutrition must change when we’re sick or injured.

Some athletes follow low carbohydrate diets to keep their body fat mass low or very low, but this can have a detrimental effect on their overall muscle mass.

If we’re exercising and deplete our carbohydrate stores (glycogen), there’s an assumption that we switch to fat. We do – to a degree – but our bodies will also make use of protein.

It may not necessarily get the energy from the protein we’ve just ingested – it can just as easily (if not more so) get it by breaking down muscle tissue.

However, after we’ve stopped exercising, proteins are used to create muscle mass, and so consuming protein after exercise is likely to create a nitrogen positive state.

The table below gives a general indication of the amounts of protein we need throughout the day. Each individual will be different, and this can be calculated for you with adjustments as necessary.

There is no evidence that increasing protein above 2g per kilogramme of body weight will be of any benefit at all. So we’re going to playing around with amounts between 1-2g.

Table 1: Protein requirements

Activity Protein requirement per kg/body mass
Sedentary  0.8
Body-building  1.61
Average gym activity  1.0-1.22
Running/cycling  1.2-1.4
1. Source: MySportsScience
2. Assuming 3 times per week, roughly an hour each time of combination aerobic and strength training

The average human being only requires around 0.8g of protein for each kilogramme of body weight. So if you weigh 80kg, then your total protein requirements throughout the day is 64g (80×0.8).

However, as we age, we become prone to a condition called sarcopenia – wastage of muscle. This is why it’s very important for older men to engage in weight-bearing exercise and slightly up their protein to around 1g per kilogramme of body mass.

Protein timing

Consider splitting your daily protein requirements into 20-25g portions.

Just as important as how much protein we need, is when should we be consuming it. Because we now know about protein turnover, it’s silly to think that all the protein we need in a day is consumed in one go.

Rather, if you want to make the most of protein, you need to spread it out over the day. Serious athletes will ensure protein is consumed around every 3-4 hours.

Foods we choose should contain all of the essential amino acids, and for some of us, leucine as well. I’ll explain this a little in a minute.

If you’re looking at protein from the point of view of sports, then consider splitting your daily protein requirements into 20-25g portions.

So if you weigh 80kg, you wish to consume 1.5g or protein per kilogramme of body mass per day, then you need: 80 x 1.5 = 120g protein daily.

Split this into meals of roughly 25g per meal means 4 meals of 25g protein and one of 20g.

For athletes, each protein source then needs around 10g essential amino acids and 3g leucine. This is why sports professionals hire nutritionists!

If you don’t do sports, then just ensure you spread your protein throughout the day and eat protein with every meal (ie, don’t just rely on carbohydrates for breakfast!)

Generally speaking, plant-based proteins don’t do quite so well with leucine as animal-based proteins – you can see from the table below that you have to eat a LOT of non-meat food to get the required 3g leucine, and this is just in one meal!

Many sports professionals will therefore get their leucine from sport supplements or from eating a lot of meat (typically chicken)!

As, there’s a lot more protein in meat, you can eat less of it. I doubt anyone would eat the portion sizes shown below for the plant-based options – so vegans who wish to gain muscle are advised to check out sites like and for ideas and advice.

Average gym-goers

So you’re just an average Joe, you like to keep fit, but you’re far from a competitive athlete – what’s the chat?

I think this is a great question. Hands up for those who’ve joined a gym, spent a lot of money on gear to motivate you, and then bought a huge tub of whey protein to drink whilst you’re there. Come on – fess up!

The truth is, if you go to the gym for about an hour say 3 or even 4 times a week, or you like to go for a run for the same duration – is there any real benefit in spending money on protein drinks?

I always say that this is a personal choice – however, why did you join the gym in the first place? Was it to lose weight, gain weight or just get fit?

If you’re eating correctly, you really don’t need that protein drink – you’re probably just going to pee it out anyway! And do you really want those extra calories?

If you eat a decent meal with protein within an hour or two of your work-out, that will do most people. The best thing you can do for yourself is keep hydrated – drink plenty of water, and if you sweat a lot, maybe choose an isotonic water.

Keep any protein drinks for days where you know you’re not going to get your daily intake – for example, you’re travelling, or you’re not well or injured yourself. Then use them to make a great green smoothie!

Table 2: What 25g protein looks like

Food source Portion size
Greek yoghurt 280g
Tofu 315g
Beans (average) 125g
Nuts (average) 125g
Vegetables (average) 830g
Grains (average) 420g
Chicken 93g
Eggs 2 eggs
Fish (average) 114g
Turkey 86g
Milk 735ml
Lentils 278g

Table 3: What 3g leucine looks like

Food source (100g) Leucine
176g Raw peanuts  3g
1L Skimmed milk  3g
300g Greek yoghurt  3g
6 eggs  3g

Protein combining

If you’re following a plant-based diet (ie, you’re vegetarian or vegan), then you’re not going to get much, if any, complete proteins from animal origins. This really only affects a few essential amino acids, mostly lysine and methionine.

For years, it was understood that vegetarians needed to combine their plant proteins in order to ensure adequate intake of protein, but current understanding is that this might not be as important as once thought.

That said, plant-based followers might benefit from knowing the old rules of protein combining.

The following groups are ideal for combining in pretty much any order:

  • vegetables
  • grains
  • nuts and seeds
  • legumes

It used to be advised that these combos were consumed at the same time, but these days, the advice is going more toward just get them in your diet.

To be honest, if you’re eating a healthy plant-based diet, you’re pretty much going to get a combination of those anyway. I’ve yet to see a vegan or vegetarian who just eats a bowl of beans or a bowl of vegetables.

In practice

So you’re following a plant-based diet and concerned you’re not getting the protein you should.

Here’s a few hints and tips for getting the right amount of protein within a balanced diet.

Breakfast – 25g protein

1 round wholemeal toast spread with half small avocado, 200g (half tin) baked beans, 100g Greek yoghurt with a few blueberries

Lunch – 25g protein

1 portion quinoa salad + 1 tsp sesame seeds. Add handful spinach leaves, 2 tbsp hummus, 10g walnuts, mixed peppers, a handful of cherry tomatoes
1 slice of cheese

Dinner – 25g protein

1 portion of meat-free moussaka plus one portion of steamed green beans and 1 portion steamed broccoli


  • Great article Seb. I’m vegan, so always interested to understand this issue more.

    • Thanks Scott! Vegans obviously have to get all their protein from plants. Most plant proteins are also beans and lentils, and these can cause some people gastric problems – so we normally suggest introducing them little by little. Anyone wanting to become vegan who’s not got a diet already high in legumes and green veg are recommended to slowly build up to veganism, letting their body adjust to the change in diet. This might be odds with their ethical beliefs if they want to go full-out straight-away.

      • Thanks Seb, yeah I’ve noticed that beans/heavy starchy veg doesn’t really agree with me. I’ve been not eating meat for over 2 years now and are doing fine. Its really just refining what I eat that works with me. Overall, I feel better not eating meat and having read a lot about the subject, believe its a better way to live. You might be interested in a book, How Not to Die by Michael Greger, who backs up all his claims with multitude of scientific research on leading a plant based diet.

  • I’m familiar with the author- the most influential book on the subject is probably The China Study by T Colin Campbell

So what do you think?

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