How much protein do you need a day? For a healthy adult, roughly 0.83 grams of protein per kilogram of bodyweight a day is a widely used baseline. If you weigh 70 kilos, that works out at around 58 grams a day. Your actual requirement depends on more than bodyweight alone, though. Your age, how much you move, your training goal, your total energy intake and the quality of your diet all play a part.
An extensive scientific review of protein intake and health describes how the 0.8 grams per kilo figure is based largely on the amount needed to meet the basic requirements of healthy adults with little physical activity. The authors give higher figures as activity increases: around 1.0 gram per kilo with little activity, 1.3 grams with moderate activity and roughly 1.6 grams with intensive physical activity.
That doesn't mean everyone automatically needs 1.6 grams per kilo. Someone who moves very little has a different requirement from someone doing strength training several times a week or training hard for Hyrox. The question isn't only how much protein you need as a minimum, then, but how much suits your body and your goal.
How do you work out how much protein you need a day?
Working out your protein requirement is straightforward: multiply your bodyweight by the amount of protein per kilo that fits your situation.
Bodyweight in kilograms × grams of protein per kilo = your daily protein requirement.
For someone weighing 70 kilograms, that gives:
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0.83 g/kg: around 58 grams of protein a day.
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1.0 g/kg: around 70 grams of protein a day.
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1.2 g/kg: around 84 grams of protein a day.
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1.6 g/kg: around 112 grams of protein a day.
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2.0 g/kg: around 140 grams of protein a day.
The familiar guideline of roughly 0.8 grams per kilo of bodyweight didn't come from nowhere. It's based largely on classic nitrogen balance measurements. Older nutrition studies looked at the protein intake at which healthy adults could maintain their nitrogen balance. Early research into the protein requirements of healthy adults showed, for instance, that relatively modest amounts of protein could be enough to maintain nitrogen balance. The authors emphasised at the same time that their results applied only to healthy adults and couldn't simply be applied to growth, pregnancy, illness or other situations where requirements change.
Is 0.8 grams of protein per kilo enough?
There's been scientific debate about this for some time. The problem is that classic nitrogen balance work mainly tries to establish how much protein is needed to prevent losses. That isn't automatically the same as the optimal amount for maintaining muscle, physical performance or maximal muscle growth.
A review by Pencharz, Elango and Wolfe therefore looks at a different method: indicator amino acid oxidation, or IAAO. Using this approach, various studies found higher estimates for the minimum protein requirement than classic nitrogen balance measurements did. The authors discuss values of around 0.9 to well over 1.0 gram per kilo of bodyweight for various groups of healthy adults, and argue that the traditional recommendations may underestimate the requirement.
That doesn't mean everyone should be eating 1.5 or 2 grams of protein per kilo daily. What it mainly shows is why a single number doesn't suit every situation.
How much protein do you need if you exercise?
When you train regularly, protein metabolism changes. During and after training, muscle tissue is continuously broken down and rebuilt. Strength training in particular raises the production of new muscle protein, which makes getting enough amino acids from food important for recovery and adaptation.
As a practical guide, you might think in terms of:
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Little to lightly active: around 0.8 to 1.0 gram of protein per kilo.
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Regularly active: around 1.0 to 1.3 grams per kilo.
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Intensive endurance sport: around 1.2 to 1.4 grams per kilo.
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Strength training and muscle building: around 1.4 to 1.8 grams per kilo is a workable range for plenty of people.
An older but influential review by Stuart Phillips on protein requirements in strength athletes shows clearly why this has been debated over the years. Strength training raises muscle protein synthesis, but it can also make the body more efficient at using protein. The review concluded at the time that athletes were often already eating more protein than necessary, and that protein supplements aren't automatically needed for muscle growth when the overall diet provides enough energy and protein.
Protein for building muscle
For people deliberately setting out to build muscle, more research is now available. A review by Schoenfeld and Aragon describes roughly 1.6 grams of protein per kilogram of bodyweight a day as a well-supported practical target for maximising muscle growth alongside strength training.
If you weigh 80 kilograms, 1.6 grams per kilo comes to around 128 grams of protein a day.
The authors stress that 1.6 grams isn't a hard ceiling beyond which extra protein suddenly does nothing. Individual requirements vary, and in the underlying literature the upper end of the confidence interval ran towards 2.2 grams per kilo per day.
Whether you train with free weights on a weight bench, do cable work on functional trainers or run a complete strength session in a home gym, enough protein supports your recovery – but the training stimulus is still what drives muscle growth.
How much protein do you need for cardio and endurance sport?
Protein is mainly associated with strength training, but it matters for endurance athletes too. During prolonged effort, amino acid turnover increases, and damaged tissue has to be repaired afterwards.
If you train regularly on rowing machines, exercise bikes or a spin bike, it's therefore sensible to look beyond carbohydrates and calories and include enough protein in your diet.
The review in Food & Function mentioned above gives figures of around 1.2 to 1.4 grams of protein per kilo for endurance athletes. The more intensively and more often you train, the more relevant proper recovery nutrition becomes.
How much protein can your body absorb per meal?
One of the most persistent myths about protein is that your body can only absorb 20 or 30 grams per meal. That isn't true. Your body can digest far larger amounts of protein and absorb the amino acids released.
The more interesting question is how much protein per meal is needed to stimulate muscle building optimally. According to the review by Schoenfeld and Aragon on protein per meal, roughly 0.4 grams of protein per kilogram of bodyweight per meal is a workable target for anyone looking to maximise muscle growth.
For someone weighing 75 kilograms that's around 30 grams per meal. Spread across four eating occasions, that comes to roughly 120 grams a day, or 1.6 grams per kilo of bodyweight.
The researchers point out explicitly that protein above this amount isn't automatically wasted. A larger portion can still be used for other tissues and bodily processes, while some of the amino acids are oxidised.
How much is 30 grams of protein?
Thirty grams of protein isn't the same as 30 grams of food. Chicken, yoghurt, eggs and pulses also consist of water, fat, carbohydrate and other nutrients.
You might get around 30 grams of protein from a generous portion of chicken or fish, a large portion of quark, a combination of eggs and dairy, or a meal with enough tofu, tempeh and other plant protein sources.
The practical Protein E-book from Beyond Nutrition also uses portions of around 30 grams of protein as a simple starting point for putting together protein-rich meals. It isn't a scientific study, but it does illustrate practically how different foods can be combined to reach that sort of amount.
How do you get 100 grams of protein a day?
For plenty of people, 100 grams of protein a day is easier to reach than it first appears. The main thing is to spread your protein across several meals rather than trying to catch up in one go in the evening.
A simple split might be:
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Breakfast: around 20 to 25 grams of protein.
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Lunch: around 25 grams of protein.
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Snack: around 15 to 20 grams of protein.
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Dinner: around 30 to 35 grams of protein.
With quark, yoghurt, eggs, chicken, fish, cottage cheese, tofu, tempeh and pulses you can reach around 100 grams a day relatively easily.
What are good high-protein foods?
A healthy high-protein diet ideally draws on several sources. That way you get not only protein but fibre, vitamins, minerals and healthy fats too.
Ten practical high-protein foods:
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Chicken breast: plenty of protein and relatively little fat.
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Fish: tuna, cod or salmon, for instance.
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Eggs: high-quality protein and various micronutrients.
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Low-fat quark: easy as a breakfast or a snack.
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Skyr: relatively high in protein per portion.
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Cottage cheese: good on bread, in salads or as a snack.
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Tofu: a versatile plant protein source.
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Tempeh: a protein-rich soya product.
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Lentils and other pulses: protein combined with plenty of fibre.
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Nuts and seeds: protein, minerals and unsaturated fats.
Does protein quality matter?
Yes. The nutritional value of a protein source is determined partly by its digestibility and its content of essential amino acids. The review by Pencharz, Elango and Wolfe discusses the DIAAS method for this, which takes the digestibility of individual essential amino acids into account.
Animal proteins such as milk, eggs, meat and fish generally contain all the essential amino acids in generous amounts. Plant proteins can contribute perfectly well to your protein intake too. On a fully plant-based diet, variety is especially important: combining pulses, soya, wholegrains, nuts and seeds gives you a range of amino acids.
How much protein is in one egg?
An average hen's egg contains roughly 6 to 7 grams of protein, so two eggs provide around 12 to 14 grams. For a protein-rich meal you might combine eggs with wholemeal bread, cottage cheese, yoghurt or other high-protein foods.
How can you increase your protein intake?
You don't have to overhaul your whole diet. Small adjustments can already make a considerable difference.
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Make your breakfast higher in protein: quark, Skyr, yoghurt, eggs or a soya product, for instance.
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Add a protein source to every main meal: chicken, fish, egg, tofu, tempeh or pulses.
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Choose high-protein snacks: cottage cheese, yoghurt or quark.
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Combine plant sources: grains with pulses, for example.
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Spread your protein across the day: so several meals contain a meaningful amount.
Do you need a protein shake?
A protein shake isn't essential. It's mainly a practical way to add protein when you're struggling to reach your daily amount through ordinary food.
The review by Phillips on strength sport and protein supplements emphasised as far back as then that there was no convincing evidence supplements are necessary for optimal muscle growth when an athlete gets enough protein and energy from normal food.
A shake can be handy after a session or on a busy day, then, but chicken, fish, dairy, eggs, soya and pulses can cover the same daily requirement.
Why can a high-protein diet help with weight loss?
Eating plenty of protein doesn't automatically produce weight loss. You lose weight when you take in fewer calories than you use over a sustained period. A higher protein intake can support that process, though.
Protein tends to be relatively filling, which can make eating less easier. Processing protein also costs energy, and enough protein during a calorie-restricted diet helps preserve as much fat-free mass as possible.
The review of protein intake and health describes studies in which a higher protein intake combined with physical activity was associated with greater fat loss and better preservation of fat-free mass during weight loss.
Strength training makes that combination more interesting still. By loading your muscles regularly and eating enough protein, you give the body a reason to hold on to muscle mass while you're trying to lose fat.
How do you notice a protein deficiency?
A serious protein deficiency is relatively uncommon in healthy people on a varied diet. The risk is greater with malnutrition, illness, a prolonged very low food intake or a severely restricted diet.
Possible signs of prolonged inadequate protein include:
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loss of muscle mass;
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reduced muscular strength;
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unintended weight loss;
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poorer physical recovery;
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physical weakness;
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with severe deficiencies, reduced immunity and fluid retention.
The scientific review by Wu describes how severe protein malnutrition can affect muscle tissue, immune function and various bodily processes. Symptoms of that kind belong to prolonged, marked deficiencies, though, and don't arise because you eat slightly less protein for a few days.
Why do older people more often fall short on protein?
As you get older, the chance of losing muscle mass increases. At the same time, plenty of older people eat less as their energy needs and appetite decline, which can bring the amount of protein in the diet down too.
Other possible causes are illness, recovery after an operation, difficulty chewing or swallowing, smaller portions and less variety in the diet.
On top of that, older muscle responds less strongly to the same amount of protein. The review on protein and human health discusses various studies in which an intake higher than 0.8 grams per kilo was associated with better support of muscle mass in older adults.
Research using the IAAO method likewise indicates that the protein requirements of older adults may be higher than classic nitrogen balance measurements suggest.
Is extra protein good for older people?
Enough protein is particularly valuable for older people in combination with physical activity. Protein provides the building blocks, while strength training provides the stimulus to maintain and build muscle tissue.
An exercise bike can be a very accessible way to move more and work on fitness. For maintaining muscular strength specifically, resistance training matters too.
For frail older people, anyone who is undernourished or people with chronic conditions, the ideal protein intake is individual. In that situation, guidance from a doctor or dietitian is sensible.
Can you eat too much protein?
Yes, but there's a large difference between a normal high-protein diet and extremely high intakes.
The review by Bilsborough and Mann on high protein intakes looked at intake in three ways: the total grams per day, the grams per kilo of bodyweight and the percentage of total calorie intake. The authors pointed out that these three figures have to be considered together, and proposed roughly 2 to 2.5 grams of protein per kilo of bodyweight as a practical maximum within the context they examined.
The same research warns mainly about extreme protein diets in which protein provides more than around 35 per cent of total energy and the absolute amount becomes very high. The authors describe how such extreme intakes can put pressure on the processing of nitrogen and urea.
Another extensive review of protein safety concludes that healthy adults can tolerate around 2 grams of protein per kilo of bodyweight over longer periods. Higher amounts have also been used without clear problems in some short-term studies, but that doesn't mean such intakes are necessary or sensible for the average person.
How do you know if you're eating too much protein?
There's no simple signal by which your body tells you you're just above your optimal protein intake. At extremely high intakes, stomach and bowel complaints can develop – nausea or diarrhoea, for instance.
A practical drawback of focusing too heavily on protein is that other foods get crowded out. If virtually every meal is built around as much protein as possible, there's a risk that less room is left for vegetables, fruit, wholegrains and healthy fats.
For healthy, active people there's therefore usually little reason to keep pushing beyond roughly 1.6 to 2 grams of protein per kilo of bodyweight without a specific goal.
Is more protein always better for muscle growth?
No. Muscle building comes from a combination of training, enough food, recovery and time. Extra protein only helps when there's a training stimulus as well.
The review of protein distribution and muscle growth arrives at roughly 1.6 grams per kilo per day as a strong practical starting point. The older review by Phillips shows at the same time that strength athletes often already take in considerable amounts of protein, and that more protein doesn't automatically produce more muscle growth.
Your training programme is therefore at least as important as your protein intake. With a weight bench you can perform presses, rows and dumbbell exercises, while functional trainers allow a wide variety of cable work. If you're training for Hyrox, you're combining strength, functional exercises and endurance, which makes both training and recovery worth attention.
How much protein do you need a day? The key conclusion
For a healthy adult, roughly 0.83 grams of protein per kilogram of bodyweight a day is a workable starting point. The optimal amount can be higher, though, if you train a lot, want to build muscle, want to lose weight while preserving muscle, or are getting older.
For people focused mainly on building muscle, roughly 1.6 grams of protein per kilogram of bodyweight a day is a well-supported practical guideline. For someone weighing 80 kilograms that means around 128 grams a day.
Don't try to get that amount from supplements alone. Build your diet around varied high-protein foods such as dairy, eggs, fish, meat, tofu, tempeh and pulses. Ideally spread your protein across several meals and combine it with a suitable training programme.
Whether you're building fitness on rowing machines, cycling regularly on exercise bikes or a spin bike, building muscle with a weight bench or training more broadly with functional trainers, nutrition and training reinforce one another. So don't look only at how much protein you eat, but at the complete picture of movement, food and recovery.
