How much protein do you actually need? An Irish evidence-based guide

Protein has become one of the most aggressively marketed nutrients in food.

Protein yogurts. Protein bars. Protein cereals. Protein water. Protein coffee. Protein desserts.

Then there is gym advice telling people to eat:

150 g. 180 g. 200 g.

every day.

But how much protein do you actually need?

For a generally healthy adult, the evidence starts much lower than many fitness feeds suggest.

EFSA’s adult Population Reference Intake is:

0.83 grams of protein per kilogram of body weight per day.

For a 75 kg adult, that is:

75 × 0.83 = 62.25 g/day

Resistance training changes the question.

A major meta-analysis found that gains in fat-free mass during resistance training plateaued at a total protein intake of approximately:

1.62 g/kg/day

with uncertainty around that estimate.

That is why Compound’s Nutrition Needs Calculator offers two deliberately different protein contexts:

• 0.83 g/kg/day for the general adult reference;
• 1.6 g/kg/day as a resistance-training evidence point.

They are not competing definitions of the same requirement.

They answer different questions.

The shortest useful answer

For a generally healthy adult:

0.83 g/kg/day is EFSA’s adult population reference intake.

For someone regularly doing resistance training and interested in maximising muscle gain:

around 1.6 g/kg/day is a reasonable evidence point from meta-analysis.

That does not mean:

• everyone who lifts weights must eat exactly 1.6 g/kg;
• 1.6 g/kg is a medical requirement;
• more protein automatically creates more muscle;
• protein powder is necessary;
• or 0.83 g/kg is the maximum amount a non-athlete can eat.

The context matters.

What does 0.83 g/kg mean in real numbers?

Here are simple worked examples.

Body weight	EFSA adult reference — 0.83 g/kg/day
50 kg	41.5 g/day
60 kg	49.8 g/day
70 kg	58.1 g/day
75 kg	62.3 g/day
80 kg	66.4 g/day
90 kg	74.7 g/day
100 kg	83.0 g/day

EFSA describes the adult Population Reference Intake as the level intended to cover the requirements of nearly all healthy adults in the population.

EFSA: protein reference values.

This is a reference intake, not a personalised sports-nutrition prescription.

Now compare the resistance-training evidence point

At 1.6 g/kg/day:

Body weight	Resistance-training evidence point — 1.6 g/kg/day
50 kg	80 g/day
60 kg	96 g/day
70 kg	112 g/day
75 kg	120 g/day
80 kg	128 g/day
90 kg	144 g/day
100 kg	160 g/day

For a 75 kg person, the difference is therefore:

• general adult reference: ~62 g/day;
• resistance-training evidence point: 120 g/day.

That is almost a doubling.

The difference exists because the questions are different.

Where does the 1.6 g/kg number come from?

A widely cited 2018 systematic review and meta-analysis examined protein supplementation during prolonged resistance training.

It included 49 studies and 1,863 participants.

The analysis found that additional dietary protein improved gains in strength and fat-free mass during resistance training.

Its breakpoint analysis estimated that additional protein above a total intake of approximately:

1.62 g/kg/day

did not produce further gains in fat-free mass in the pooled resistance-training data.

Morton et al. 2018.

That does not establish a biological cliff at exactly 1.62.

It is a statistical estimate across many studies and participants.

Your body does not know whether you consumed 1.59 or 1.64 g/kg.

More recent evidence broadly supports the idea that more is not infinitely better

A 2022 systematic review and meta-analysis included 74 randomised controlled trials.

It found that increasing daily protein intake produced small additional gains in lean body mass in healthy adults doing resistance exercise.

The analysis reported benefits in younger adults at intakes of at least around 1.6 g/kg/day, while results varied by age, outcome and baseline intake.

The authors also found only small or unclear effects for several strength and physical-function outcomes.

Nunes et al. 2022.

This is a useful antidote to a common misunderstanding:

Protein supports adaptation to training, but protein is not a substitute for training.

The exercise stimulus matters enormously.

Does everyone who goes to the gym need 1.6 g/kg?

No.

“Regular resistance-training context” covers a huge range of people.

Someone who:

• lifts twice a week for general health;
• eats an already protein-rich diet;
• is not trying to maximise muscle gain

is asking a different question from someone doing structured progressive resistance training five days a week.

The 1.6 g/kg figure is useful as an evidence point, not as a compulsory minimum for anyone with a gym membership.

That is why the calculator labels it that way.

Is 0.83 g/kg an “optimal” intake?

That depends on what you mean by optimal.

EFSA’s 0.83 g/kg is a population reference intake designed to cover the protein requirements of healthy adults.

It is not intended to answer:

What total intake maximises resistance-training hypertrophy?

Likewise, the resistance-training literature is not designed to establish the ideal diet for every healthy adult.

One number is a nutritional reference.

The other is a sports-performance evidence point.

Treating them as if one must be “right” and the other “wrong” creates unnecessary confusion.

How much protein does a 90 kg person need?

This is a useful example because internet advice can diverge quickly.

At 90 kg:

General adult reference

90 × 0.83 = 74.7 g/day

Resistance-training evidence point

90 × 1.6 = 144 g/day

Difference:

69.3 g/day

Neither result tells us:

• medical history;
• body composition;
• training programme;
• energy intake;
• whether weight loss is occurring;
• pregnancy status;
• age-related clinical nutrition needs.

The Nutrition Needs Calculator is therefore for generally healthy adults and deliberately excludes situations requiring more individual assessment.

Do you need protein powder?

No.

Protein powder is a food supplement, not a requirement for muscle growth.

Its main advantage is convenience.

Someone can meet protein needs using ordinary foods such as:

• milk;
• yogurt;
• eggs;
• fish;
• poultry;
• lean meat;
• beans;
• lentils;
• chickpeas;
• tofu;
• soya foods;
• nuts and seeds.

The HSE recommends including a variety of lean meat, poultry, fish, eggs, nuts or beans in two meals per day as part of a balanced diet.

HSE: how to eat well.

A supplement becomes useful mainly when it makes the overall diet easier to execute.

It does not create a special category of protein that the body otherwise cannot obtain.

Irish serving guidance is food-based, not macro-tracking based

Healthy Ireland’s Food Pyramid recommends:

two servings per day

from the meat, poultry, fish, eggs, beans and nuts shelf.

Examples from current Irish guidance include:

• 50–75 g cooked lean beef, lamb, pork, mince or poultry;
• 100 g cooked fish, soya or tofu;
• 2 eggs;
• ¾ cup beans or lentils;
• 40 g unsalted nuts or seeds.

Healthy Ireland: Food Pyramid.

This does not mean those are the only foods contributing protein.

Milk, yogurt, cheese, grains and other foods can contribute too.

The Food Pyramid is designed around the whole diet, not a single macro target.

Protein foods bring other nutrients with them

This is one reason a “highest protein per calorie” ranking can be nutritionally simplistic.

Different protein sources also provide different combinations of:

• iron;
• vitamin B12;
• calcium;
• iodine;
• omega-3 fats;
• fibre;
• zinc;
• other vitamins and minerals.

Beans and lentils, for example, also contribute fibre.

Oily fish contributes long-chain omega-3 fats.

Dairy foods can contribute calcium and iodine.

Protein quantity is important.

Food quality still matters.

For the broader nutrient picture, see Macronutrients and micronutrients: a complete guide for Ireland.

Can your body only absorb 20 or 30 grams of protein at once?

No.

The body can digest and absorb more than 20–30 g of protein in a meal.

The popular claim confuses absorption with the acute muscle-protein-synthesis response.

A 2018 review specifically examined the idea of a maximum usable amount per meal.

The authors noted that amino acids from larger meals are not simply discarded.

Some may be oxidised, but amino acids also have uses throughout the body beyond skeletal-muscle protein synthesis.

Schoenfeld and Aragon 2018.

So:

“Your body wastes anything above 30 g”

is not an accurate description of human protein metabolism.

Does spreading protein across the day matter?

It may be sensible, particularly for someone trying to support muscle protein synthesis.

The 2018 review proposed roughly:

0.4 g/kg per meal

across at least four meals as one way to distribute a 1.6 g/kg/day intake.

For a 75 kg person:

75 × 0.4 = 30 g per meal

Across four meals:

120 g/day

That is mathematically neat.

But it should not be turned into another rigid rule.

A review of protein distribution research concluded that evidence for a uniquely “optimal” distribution pattern remains limited and inconsistent.

The total amount consumed across the day remains highly important.

Do you need a protein shake immediately after training?

The famous 30-minute “anabolic window” is much less dramatic than marketing often suggests.

A 2020 systematic review led by UCD researchers found no clear benefit of a specific protein timing strategy for lean body mass or strength.

Wirth et al. 2020.

A 2025 meta-analysis directly comparing protein consumed before versus after exercise found no important difference in changes in lean body mass.

Casuso and Goossens 2025.

For most healthy people doing resistance training, the practical hierarchy is therefore closer to:

1. train consistently;
2. eat enough total protein;
3. eat an overall adequate diet;
4. distribute protein reasonably across the day;
5. worry about minute-by-minute timing much later.

You do not need to sprint from the squat rack to a shaker bottle.

That does not mean timing is completely irrelevant

Exercise changes muscle-protein metabolism, and a protein-containing meal around training is perfectly sensible.

The point is narrower:

the evidence does not justify treating a tiny post-workout time window as the dominant variable.

If you had a protein-containing meal before training and eat another normal meal afterwards, there is little reason to behave as though your workout is being wasted every minute you delay a shake.

Protein alone does not build muscle

Muscle growth requires an appropriate training stimulus.

Protein provides amino acids used in repair and remodelling.

Without progressive resistance training, increasing protein intake does not recreate the effect of training.

The 2022 meta-analysis found the clearest additional lean-mass benefits from higher protein in people undertaking resistance exercise.

This matters because protein foods and supplements are often marketed as if the nutrient itself is anabolic enough to compensate for weak training.

It is not.

Calories still matter

Protein is only one part of the diet.

If total energy intake is inadequate, training recovery and body-mass goals can be affected.

If total energy intake is consistently above expenditure, body weight can rise regardless of whether the extra calories came from “healthy” protein foods.

The Nutrition Needs Calculator therefore estimates:

• resting energy expenditure;
• activity-adjusted maintenance energy;
• protein;
• an illustrative fat allocation;
• carbohydrate remainder;
• fibre reference.

It does not calculate protein in isolation from the rest of the diet.

Where does the calorie estimate come from?

The tool uses the Mifflin–St Jeor equation to estimate resting energy expenditure.

It then applies an activity factor based on EFSA-style Physical Activity Level values.

That produces an estimate of maintenance energy.

It is not a laboratory measurement.

Two people with the same:

• age;
• height;
• weight;
• sex

can still have different real energy expenditure.

The calculator makes that uncertainty explicit.

A 75 kg worked example

Take a generally healthy 35-year-old adult weighing:

75 kg

Protein results:

General adult reference

62.3 g/day

Resistance-training evidence point

120 g/day

The tool may also estimate maintenance calories from height, age, sex and selected activity level.

But protein does not need to be calculated as a fixed percentage of calories.

It is usually more useful here to calculate protein relative to body weight, then build the rest of the diet around energy needs and food quality.

A 100 kg person does not automatically need 200 g of protein

A common gym heuristic is:

2 g/kg

For a 100 kg person, that becomes:

200 g/day.

That may be an intake someone chooses in a particular sports context.

But it should not be confused with the adult reference intake, which would be:

83 g/day

or with the calculator’s resistance-training evidence point:

160 g/day.

More protein is not automatically better simply because it is more.

What about protein during weight loss?

This is an area where context becomes more individual.

Energy restriction can change the value of higher protein intake for:

• satiety;
• preservation of lean mass;
• training recovery.

But an appropriate intake can depend on body composition, severity of the calorie deficit, training and medical context.

Compound therefore does not add a “cutting protein” mode that pretends one number is universally correct.

The calculator’s 10% lower-energy option is explicitly labelled an illustrative mathematical scenario, not a prescribed diet.

What about older adults?

Ageing raises an important but more nuanced question.

Research suggests older adults can show a different anabolic response to protein and exercise, and some scientific groups propose higher intakes or larger per-meal doses in older people.

Healthy Ireland’s guidance for older adults also emphasises having a source of protein at each meal.

However, an older adult with:

• frailty;
• unintended weight loss;
• reduced appetite;
• kidney disease;
• other medical conditions

may need individual clinical nutrition advice.

A general web calculator should not pretend to replace that.

What about kidney disease?

This tool is not intended for people who require medical nutrition therapy.

Someone with diagnosed kidney disease or another condition where protein intake has been medically discussed should follow their clinician or dietitian’s advice rather than using a general sports-nutrition target from a website.

The same principle applies to conditions involving significant metabolic or nutritional management.

Pregnancy and breastfeeding need different guidance

The calculator is not designed for pregnancy or breastfeeding.

Protein and total energy requirements change during these periods, and the relevant nutritional guidance is different from a general adult gym calculation.

Likewise, it is not intended for children or teenagers.

Protein bars versus ordinary food

A food having “protein” in large letters on the front does not automatically make it nutritionally superior.

Check the whole product.

Questions worth asking include:

• How much protein does it provide?
• What is the total energy content?
• How much saturated fat?
• How much sugar?
• How much salt?
• What does it replace in the diet?
• Is it actually convenient enough to justify the price?

A protein bar can be useful.

So can a yogurt, sandwich, eggs, milk, beans or an ordinary meal.

Protein is a nutrient, not a halo.

Plant protein counts

Protein does not have to come from meat.

Irish healthy-eating guidance explicitly includes:

• beans;
• lentils;
• chickpeas;
• nuts;
• seeds;
• tofu;
• soya

as protein sources.

Healthy Ireland recommends using beans, pulses and other plant proteins in meals and includes them in the same protein-food shelf of the Food Pyramid.

A varied plant-based diet can provide protein, but the broader nutrient pattern also matters.

Do incomplete proteins need to be combined at every meal?

The old idea that plant proteins must be carefully paired in the same meal is overly rigid.

What matters is consuming an adequate and varied diet across the day.

Different plant foods contribute different amino-acid profiles.

Someone following a highly restricted diet may need to pay more attention to overall protein quality and other nutrients, but there is no need for healthy adults to micromanage every mouthful into a perfect amino-acid combination.

How should you use the calculator?

Use the Nutrition Needs Calculator in this order.

1. Enter body weight, height and age

These feed the energy equation and the protein calculation.

2. Choose the activity level realistically

The activity estimate is one of the least precise inputs.

Do not choose “very active” because you train for an hour but sit for most of the remaining day.

3. Choose the protein context

Use:

General adult reference

to see the EFSA 0.83 g/kg figure.

Use:

Regular resistance-training context

to see the 1.6 g/kg evidence point.

4. Treat calories as an estimate

Your actual body-weight trend over several weeks contains useful information about whether the estimate matches reality.

5. Build meals from foods, not just numbers

A protein target met through a low-fibre, low-fruit, low-vegetable diet is not automatically a high-quality diet.

A sensible priority order

For most generally healthy adults, the practical order is:

First — eat an overall balanced diet

Use the Irish Food Pyramid as the base.

Second — meet a reasonable total protein intake

The appropriate context depends on your goals.

Third — resistance train if muscle and strength are the objective

Nutrition supports the training response.

Fourth — spread protein across normal meals

You do not need to consume the entire day’s intake at dinner.

Fifth — use supplements only if they solve a practical problem

Convenience can be valuable.

It is not the same thing as necessity.

The bigger nutrition picture

Protein gets disproportionate attention because it is easy to quantify and market.

But a healthy diet also requires attention to:

• vegetables and fruit;
• whole grains;
• fibre;
• dietary fat quality;
• vitamins;
• minerals;
• overall energy intake.

WHO guidance used in Compound’s calculator sets an adult dietary-fibre reference of at least 25 g/day, while Irish guidance recommends 5–7 servings of fruit, vegetables and salad per day.

A diet can hit 160 g of protein and still be poor.

For the wider picture, read Macronutrients and micronutrients: a complete guide for Ireland.

The practical conclusion

The answer to “how much protein do I need?” should begin with:

What are you trying to achieve?

For a generally healthy adult, EFSA’s reference is:

0.83 g/kg/day.

For someone doing regular resistance training and asking about an evidence-based intake associated with maximising muscle gains:

around 1.6 g/kg/day is a useful reference point from the research.

Neither number needs to become a dietary obsession.

Use the Nutrition Needs Calculator to put your own body weight into both contexts.

Then focus on what matters more than chasing another 10 grams:

consistent training, sufficient total nutrition, a varied diet and a plan you can actually sustain.