A healthy adult needs 0.83 grams of protein per kilo of body weight per day according to the European reference value. With strength training the gain continues to roughly 1.3 to 1.6 grams per kilo, above which the curve flattens. And the figure of 2.3 to 3.1 grams that circulates everywhere refers to lean mass, not body weight.
A healthy adult needs 0.83 grams of protein per kilo of body weight per day. That is the European reference value and it appears exactly like that in the Belgian dietary recommendations. For someone of 75 kilos that comes to about 62 grams.
If you train with weights the number climbs: the research points towards 1.3 to 1.6 grams per kilo. Above that the gain flattens out.
That is the short answer. Below you will find where those numbers come from, where the researchers disagree and which calculation error sits in almost every article on this subject.
The European food safety panel calculated the average requirement at 0.66 grams per kilo per day, based on nitrogen balance studies. To also cover people at the top of the distribution, the recommendation became 0.83 grams per kilo per day.
The Belgian Superior Health Council adopts that figure literally. For endurance athletes the same recommendation sets the bar at a minimum of 1.2 grams per kilo.
Most people reach that 0.83 without thinking about it. In practice the minimum is rarely the problem. It is what you need the moment you start training or start cutting.
Source: EFSA-panel NDA1 2012, EFSA Journal · Hoge Gezondheidsraad2 2016
The most quoted figure comes from a meta-analysis of 49 studies with 1863 participants. Above 1.62 grams per kilo per day, extra protein delivered no further lean mass.
That number is almost always presented with too much certainty. The confidence interval runs from 1.03 to 2.20 grams. The break point analysis ran on 42 study arms with 723 participants rather than the full dataset. The authors themselves write that it may be prudent to recommend up to 2.2 grams for those chasing the maximum.
A larger analysis, 105 articles with 5402 participants, saw the curve flatten from 1.3 grams per kilo onwards. Below that line every extra 0.1 grams per kilo still delivered 0.39 kilos of lean mass, above it only 0.12 kilos. For strength the turning point sits around 1.5 grams per kilo.
So there is no wall. There is a curve that flattens, somewhere between 1.3 and 1.6 grams per kilo.
One figure from that same analysis deserves attention: without strength training, extra protein had no effect at all on strength. Protein does nothing on its own. It finishes what your training sets in motion.
Source: Morton et al.3 2018, British Journal of Sports Medicine · Tagawa et al.4 2021, Nutrition Reviews · Tagawa et al. 2022, Sports Medicine - Open
Search for how much protein you need while losing fat and you will run into 2.3 to 3.1 grams per kilo. That figure is correct. The unit attached to it almost never is.
In the original review it reads 2.3 to 3.1 grams per kilo of lean mass. So per kilo of your body without the fat. Almost every reproduction attaches body weight to it instead.
The difference is substantial. Someone of 80 kilos at 20 per cent body fat carries 64 kilos of lean mass. According to the review that person lands at 147 to 198 grams of protein a day. Calculate it wrongly on body weight and you get 184 to 248 grams. A quarter more, every single day.
Look at who was studied as well: trained, lean athletes with at least six months of strength training behind them. Someone wanting to lose fifteen kilos sits in a different situation. And it was only six studies.
Source: Helms et al.6 2014, International Journal of Sport Nutrition and Exercise Metabolism
A meta-analysis of 18 studies looked at what protein above the reference value delivers. The answer is sharper than you would expect.
During a calorie deficit the protein group preserved an average of 0.36 kilos more lean mass. With strength training the gain rose to 0.77 kilos. Without a deficit and without strength training: no difference.
Extra protein works specifically when your body is under pressure. If you eat normally and do not train, more protein does nothing measurable for your muscle mass.
Something else weighs heavier than your protein intake: the size of your deficit. In a meta-analysis a deficit of roughly 500 kcal per day blocked lean mass gain completely, while strength gains continued. Anyone wanting to keep muscle while losing fat is better off staying under that line.
Source: Hudson et al.7 2020, Advances in Nutrition · Murphy & Koehler8 2022, Scandinavian Journal of Medicine & Science in Sports
This is the point where copy goes too far fastest, so here are the measured numbers.
In a meta-analysis of 49 publications, hunger dropped by 7 millimetres on a 100-point scale after a protein-rich meal. Fullness rose by 10 millimetres. Ghrelin, the hunger hormone, came down. All of it statistically convincing.
And then the sentence that is rarely quoted: over the longer term the same researchers found no effect on appetite any more. Their own conclusion is that the long-term trials give no conclusive answer.
So protein helps measurably on the day itself. That it makes you eat less by itself over weeks has not been demonstrated.
Source: Kohanmoo et al.9 2020, Physiology & Behavior
Here two authoritative bodies genuinely contradict each other, and you deserve to know that.
The European panel writes that the protein requirement in older people equals that of younger adults. So 0.83 grams per kilo. The Belgian recommendation follows suit and gives people over sixty exactly the same value.
Two international expert groups from clinical geriatrics arrive at 1.0 to 1.2 grams per kilo for healthy older adults. In case of illness that becomes 1.2 to 1.5.
The difference lies in the question they ask. The food safety panel checks whether you are deficient. The clinical groups check whether you can still get out of an armchair on your own at eighty. Those are two different bars.
One caveat that appears in no popular article: anyone with serious kidney disease who is not on dialysis may need to limit protein instead. Discuss that with your doctor.
Source: Bauer et al.10 2013, Journal of the American Medical Directors Association · EFSA-panel NDA1 2012
As a historian I also look at who settled the bill. That belongs in this file.
Morton's meta-analysis draws in part on studies funded by the American dairy council. In the 2022 dose-response analysis, five of the seven authors work for a dairy company. The 2022 review that actually shrinks the effects has ties to supplement manufacturers.
That does not make those numbers worthless. It is a reason to pay attention to who claims you need more. And to notice why the largest analyses keep finding lower turning points than the headlines suggest.
Source: Morton et al.3 2018 · Tagawa et al.4 2022 · Nunes et al.11 2022
The numbers above become useful the moment you do something with them. In practice I see three things that weigh more than the third decimal.
You rarely hit your target in one meal. Four moments of 25 to 40 grams each is easier to sustain than one giant portion in the evening. You usually do not know what you take in: anyone who tracks it for a week is generally surprised by their breakfast. And according to the largest analysis, protein without strength training does nothing for your strength.
That is what I build a plan around, one that fits your week rather than a number you picked up from an article.
| Situation | Grams per kilo per day | Where the number comes from |
|---|---|---|
| Healthy adult, no training | 0.83 | European reference value, also adopted in Belgium |
| Endurance sport | at least 1.2 | same Belgian recommendation |
| Strength training, muscle mass | 1.3 to 1.6 | two dose-response analyses, over 7000 participants |
| Strength training, strength | up to 1.5 | meta-analysis of 82 articles |
| Losing fat while keeping muscle | 1.6 to 2.4 | converted to body weight, see the calculation error below |
| From 65 years | 1.0 to 1.2 | clinical expert groups, more than the official reference |
The European reference value for a healthy adult is 0.83 grams per kilo of body weight per day. For someone of 75 kilos that is about 62 grams. If you do strength training, the research points towards 1.3 to 1.6 grams per kilo, so 98 to 120 grams.
In a meta-analysis of 49 studies with 1863 participants, the point beyond which extra protein gave no further gain sat at 1.62 grams per kilo per day. The confidence interval ran from 1.03 to 2.20 though, so that is an estimate rather than a sharp line. A larger analysis of 105 articles with 5402 participants already saw the curve flatten from about 1.3 grams per kilo.
For most people it is not demonstrable. The upper bound of the confidence interval in Morton sits at 2.2 grams, so anyone chasing the maximum could land there. The measured added value above 1.6 is small to absent.
The best known review names 2.3 to 3.1 grams per kilo of lean mass. For someone at 20 per cent body fat that works out at roughly 1.8 to 2.5 grams per kilo of body weight. A meta-analysis of 18 studies found that more protein during a deficit preserved an average of 0.36 kilos of extra lean mass.
In the short term, measurably. In a meta-analysis of 49 publications hunger dropped by 7 millimetres on a 100-point scale and fullness rose by 10 millimetres. Over the longer term the same researchers found no effect any more. So it is a modest help on the day itself.
Two international expert groups arrive at 1.0 to 1.2 grams per kilo per day for healthy older adults. In case of illness that becomes 1.2 to 1.5. The official European and Belgian reference value stays at 0.83. Anyone with serious kidney disease should discuss this with their doctor first.
There is too little data to set a safe upper limit. The European panel does state that intakes up to twice the reference value, so roughly 1.66 grams per kilo, are regularly consumed by healthy active adults in Europe and are considered safe.
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