How Much Protein Do You Really Need?

You’ve been told two different stories about protein, and they can’t both be true. One says that anything above a modest official target is a fad that wrecks your kidneys, leaches calcium from your bones and then, if you pass a certain amount in a single meal, is flushed down the loo. The second says you need a cupboard bursting with protein supplements, timed to the second pre- and post-workout; otherwise, your muscles will resolutely refuse to grow. Most people—especially women between the ages of thirty and sixty-five—who would like to remain healthy, energetic, and vital, with a body and mind that hold together, probably need to ignore both of those stories. 

The truth is that many people don’t get enough protein for reasons that will become clear. Protein is not just a gym nutrient. It’s the stuff of life. What follows is everything you need to know about protein, and probably a lot more: the physiology, the numbers, the quality issues, the benefits, the issues and the myths, topped off with some actionable measures to take. Feel free to read through it, or jump from heading to heading. 

What Is Protein?

Proteins are like LEGO toys. Each toy is built from blocks that determine how it functions; the possibilities are limitless. Amino acids are the LEGO blocks of proteins, the shapes of which determine their function as, for example, enzymes, structural proteins, hormones, antibodies, transporters and much more. Humans use 20 standard amino acids; nine of which are ‘essential’, meaning we must obtain them from the diet because we can’t synthesise them in high enough amounts. They are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. These amino acids are dietary non-negotiables.  

Food sources that contain all nine essential amino acids in high enough amounts to keep people healthy are called ‘complete proteins’; they should make up the cornerstone of someone’s daily protein intake. The best sources of complete proteins come from things that had seeing eyes: animals and their products, including eggs and dairy. Other sources that just scrape the ‘complete’ title are soy, fungi, pistachios and some seeds. In recent years, other foods have started to creep onto some lists, buckwheat and potato, for example, but they are ‘nearly complete’ proteins, in other words, not complete. The amino acids they fall short on must be added. 

Incomplete proteins don’t contain all nine essential amino acids in high enough amounts. These include collagen, legumes, most nuts and seeds, whole grains and certain vegetables. Combining some of these foods, grains with legumes for example, does create a complete protein, but there are downsides with this approach which we’ll tuck into later. 

The History of Protein: From Discovery to Modern Science

Long before scientists coined the term ‘protein’, people everywhere knew instinctively that meat, dairy and eggs sustained health, growth and strength in ways that plant foods alone did not. Milo of Croton, a legendary strongman from Ancient Greece, was said to eat prodigious amounts of meat every day. Legend has it that Milo’s meat-based diet lent him strength enough to heft a calf onto his shoulders every day, even as it grew into a full-sized bull at which time, naturally, he ate it. It’s not clear whether he devoured it in one sitting or over a few meals; this detail is lost to history. 

The word ‘protein’ was coined in 1838 by a Swedish scientist called Jöns Jacob Berzelius. Before that, scientists referred to proteins as albuminous or nitrogenous substances, depending on whether they were studying egg whites or meat, respectively. In 1819, scientists isolated leucine, but it wasn’t until 1936, after other scientists isolated threonine, that the world had the full set of 20 proteinogenic amino acids. 

Today, scientists can determine the protein content of all foods, allowing them to turn some incomplete protein sources, such as rice and peas, into complete ones. By concentrating certain plant parts, modern industrial processing leaves only protein, at the cost of other nutrients found in whole foods; just because we can doesn’t mean we should. 

How Protein Works in the Body

Put simply, proteins have two major functions in the body. Firstly, they are the building blocks of our structures: muscles, collagen, bones, skin, organs, etc. Secondly, they have functional roles as enzymes that catalyse chemical reactions, peptide hormones (insulin, growth hormone, etc.), signalling molecules, antibodies in our immune system, nutrient carriers, cell transporters (moving nutrients in and out of cells), receptors that detect signals, and many other functions. 

When we eat proteins, complete or incomplete, they are broken down in the stomach and small intestine by stomach acid and proteases. Proteases are protein-digesting enzymes that snip long chains of amino acids into smaller units called peptides and individual amino acids. These are absorbed into the bloodstream and then into the tissues. This relatively small pool of proteins needs constant topping up by the diet because, despite a high rate of amino acid recycling, we are continuously losing them. We ‘burn’ (oxidise) amino acids for fuel, convert them into other molecules and excrete them. Humans shed skin, hair, nails, and intestinal lining. We bleed and void digestive secretions, amongst other things. This never-ending cycle is part of what’s called protein turnover. 

Protein turnover is the balance between the synthesis of new proteins and the breakdown of old ones. Proteins are in constant flux, being broken down and built up even as they function. This process removes damaged, misfolded (dysfunctional), oxidised or otherwise non-functional proteins and allows rapid adaptation to changing conditions and developmental signals originating from our environment. Every day, your amazing body synthesises and degrades about 400 grams of protein, even during severe illness or starvation. Prolonged fasting strips the body of muscle mass like nothing else; this occurs as the body prioritises life-sustaining functions over muscle tissue. 

Muscle protein synthesis (MPS) and the mTOR pathway

The anabolic (growth) side of protein turnover is called muscle protein synthesis (MPS) and is largely governed by a metabolic switch and signalling pathway known as mechanistic target of rapamycin complex 1 (mTORC1). mTORC1 is strongly activated by resistance training, ample consumption of protein, especially the amino acid leucine, and by a well-calibrated circadian rhythm. Combining resistance training with the recent consumption of a complete protein, containing about 3 grams of leucine, has a stronger mTORC1 activating effect than those things in isolation.  

Protein Benefits for Muscle Strength, Performance and Recovery

The dry weight of healthy muscle tissue is 70% to 80% protein; this is true of all mammals. All twenty standard amino acids go into building muscle mass, but the essential amino acids (EAAs), especially leucine, are the real contributors. EAAs trigger muscle protein synthesis and provide the raw materials. Leucine is a uniquely potent MPS trigger; without enough of it, even if there are plenty of other amino acids available, the ‘on’ signal remains at baseline and increases in muscle mass (hypertrophy) don’t rise above that level. Put simply, without enough leucine your muscles won’t grow. 

Resistance training and hypertrophy

A resistance training session increases muscle protein breakdown, elevates the muscle’s sensitivity to amino acids for several hours afterwards, and strengthens the MPS signal in the presence of leucine. Add a complete protein shortly after your workout, and muscle hypertrophy increases well above baseline. We start adding more muscle than we break down and become stronger. 

High-intensity Exercise

During high-intensity exercise, protein acts as a supporting nutrient rather than a performance enhancer, like creatine. High-intensity efforts create significant microtrauma, which in turn increases muscle protein breakdown. As you rest, providing your muscles with enough protein allows them to shift back to a net positive MPS. All that microtrauma has healed, and the muscle has now adapted and become stronger, ready for the next session. 

Optimal protein timing

The total daily intake and per-meal dose matter more than precise timing. Certain types of sportspeople, strength athletes for example, need to consume higher amounts of protein so they may want to devise strategies to achieve optimum results by dialling in their protein type and timing, but for the average person, this is overkill. 

As long as people are eating enough complete protein with adequate leucine, their muscle strength, performance, and recovery will be as close to optimal as their training. That said, there are some practical timing tips that ensure your muscles don’t go wanting when they need protein the most.  

If you want to know how much protein you should be aiming for, see Table 2: Optimal Protein Requirements

• Prioritise high-quality sources that provide all the essential amino acids and ample leucine.

• Divide your daily protein requirements fairly evenly across three major meals. 

• If needed, use a couple of snacks to bump it towards your goal.

• Eat a complete protein-containing meal every 3-5 hours across your waking day. 

• Include a solid serving of protein in the meal closest to your training session (before, after, or both). There is no need to rush a shake within 30 minutes if you have already eaten protein in the preceding few hours.

• For athletes and people chasing hypertrophy, consider a pre-sleep serving of a slow-releasing protein like casein, especially on training days or if your last meal is early in the evening.

Protein timing mistakes 

• Obsessing over minute-level timing at the expense of total intake or overall diet quality.

• Very large single boluses that leave long gaps without protein.

Protein & longevity

When protein intake is insufficient, net protein balance becomes negative. Over months and years, this contributes to a gradual loss of muscle mass and strength. In older adults, the muscle becomes less responsive to amino acids (anabolic resistance), so higher per-meal and daily protein intakes are needed to achieve the same stimulatory effect seen in younger people. We’ll get into the nitty-gritty of protein dosage later, but higher than currently recommended protein intakes (commonly in the range of 1.2 g/kg/day or above, combined with resistance exercise) have been shown to help preserve lean mass, improve strength and slow the progression of sarcopenia.

Low muscle mass and sarcopenia are robustly associated with higher all-cause mortality in middle-aged and older adults. Meta-analyses of prospective studies show that people with low lean mass or diagnosed sarcopenia have a substantially elevated risk of death (typically 30–80 % higher, depending on the definition and population). The association extends to cardiovascular, cancer and respiratory mortality and remains significant after adjustment for common confounders.

Muscle is not merely structural tissue. It supports mobility, insulin sensitivity, immune function and resilience to acute illness or injury. Loss of muscle increases the likelihood of falls, prolonged hospital stays, disability, and loss of independence, all of which are independent risk factors for mortality. Data from over one million people found that muscle strength (for example, grip strength) is an even stronger predictor than muscle mass alone, but the two are closely linked.

Protein is one of the key modifiable factors that influence whether muscle mass and strength are preserved with age. By helping to maintain a more favourable balance between muscle protein synthesis and breakdown, adequate protein intake reduces the risk of sarcopenia, lowers sarcopenia rates, and, in turn, supports better physical function and lower mortality risk.

In older age, the priority shifts: insufficient protein accelerates muscle loss, while sufficient protein (especially when paired with resistance exercise) helps preserve muscle mass, which, in turn, predicts longer survival and a better healthspan.

Protein for Brain Health, Cognition and Mental Performance

Several essential and non-essential amino acids act as the raw materials from which the brain manufactures its major neurotransmitters. Glutamate, GABA, dopamine, serotonin, and norepinephrine are all built with micronutrients, especially amino acids. Neurotransmitters are the brain’s chemical messengers. They carry signals between nerve cells and help regulate mood, motivation, focus, sleep, stress responses and many other aspects of how we think and feel.

Tryptophan is the sole precursor of serotonin, which in turn is further converted into melatonin, our sleep hormone. Tyrosine and phenylalanine are precursors of the neurotransmitters dopamine, norepinephrine, and adrenaline. Glutamate itself functions as the principal excitatory neurotransmitter and is also the precursor of the main inhibitory neurotransmitter GABA (gamma-aminobutyric acid). 

Because neurotransmitter synthesis is partly amino acid-dependent, chronic low protein intake or periods of energy deficit can reduce the availability of these precursors. In aged animals, protein deficiency has been shown to impair learning and lower brain levels of key neurotransmitters; these deficits can be reversed by restoring essential amino acids.

In humans, the picture is more mixed. Several observational studies in older adults report positive associations between higher protein intake and better scores on general cognition, memory, or executive function tests. Proposed mechanisms include better maintenance of neurotransmitter pools, reduced frailty and sarcopenia (both of which correlate with cognitive decline), and improved overall nutritional status. However, systematic reviews of the observational literature find inconsistent results for overall cognition, with clearer signals sometimes appearing for specific areas such as memory. Unfortunately, observational nutrition studies are notoriously unreliable, so clinical trials should provide more reliable data.

Clinical trials specifically testing the quality of protein supplementation for cognitive outcomes in older adults remain relatively few. One systematic review of 23 randomised controlled trials found modest cognitive benefits in psychomotor control, attention, memory and cerebral blood flow. However, many of the trials were very different and used poor-quality proteins, including peanuts and soy. Some well-designed research studies using nutrient-dense animal protein are desperately needed. 

Protein for Gut Health, Immunity, Metabolic Health and Detoxification

Protein for gut health

Adequate dietary protein helps defend against ‘leaky gut’ by maintaining the intestinal barrier and supporting the production of tight-junction proteins. Mucin (the protective mucus layer) and secretory IgA, its main antibody and first line of defence inside the small intestine, are made predominantly of amino acids. In experimental models, low-protein diets worsen colitis and increase gut permeability, while specific amino acids (notably arginine and glutamine) reinforce barrier integrity and reduce inflammation. Human evidence in inflammatory bowel disease (IBD) is still emerging but supportive of adequate protein as part of overall care.

Protein for immune modulation

Amino acids serve as both energy substrates and building blocks for rapidly dividing immune cells. Glutamine is especially critical for enterocytes (gut lining cells) and lymphocytes (lymph cells); the amino acid supports T-cell proliferation, cytokine production and antibody (including secretory IgA) synthesis. Other amino acids such as arginine, cysteine and the branched-chain amino acids (leucine, isoleucine and valine) also modulate immune-cell function and cellular redox (including balancing oxidative stress), which determines, in part, how well the cell functions. Protein deficiency impairs these processes and increases susceptibility to infection, which is why the tragedy of famine is so often compounded by deadly infection. 

Protein for satiety, weight loss and glycaemic control

It’s well understood that of the three macronutrients, protein produces the strongest satiety response. Protein intake lowers the hunger hormone ghrelin and raises the satiety hormones GLP-1 and cholecystokinin (CCK) more effectively than matched-calorie carbohydrate or fat diets. Obviously, greater satiation increases the chances people will eat less overall. Weight-loss drugs, specifically GLP-1 receptor agonists such as Wegovy and Ozempic, work through this satiety mechanism.

Protein also has the highest thermic effect of the macronutrients (roughly 20–30 % of its energy content is used in digestion and metabolism, versus ~5–10 % for carbohydrate and ~0–3 % for fat). These effects contribute to better body composition and can support glycaemic control by reducing overall energy intake, reducing carbohydrate consumption and maintaining metabolically active tissue. High-protein diets have been repeatedly shown to be an effective and safe tool for weight loss that can prevent obesity and obesity-related diseases.

Protein for natural detoxification

Glutathione is the body’s main antioxidant inside cells and also plays a central role in Phase II liver detoxification, the step before excretion. The tripeptide (made of three amino acids) is composed of glycine, cysteine, and glutamate. Of these, cysteine is usually the rate-limiting one, so if supplies are low, glutathione production slows down.

Other amino acids also help with detoxification. Glycine, taurine and glutamine, for example, can be attached directly to certain toxins (a process called conjugation). This makes the toxins more water-soluble so they can be excreted easily in urine or bile.

These pathways work best when protein intake is adequate rather than excessive. If protein (and therefore the necessary amino acids) is in short supply, the body has less raw material with which to make glutathione and to carry out conjugation, which can reduce its ability to neutralise and clear toxins.

How Much Protein Do You Need, and What Is Optimal? 

See Table 2: Optimal Protein Requirements for reference amounts based on the discussions herein. 

British committees have been wrestling with protein recommendations for decades, opting for something closer to a guess than a precise scientific recommendation. In 1950, the British Medical Association’s Nutrition Committee declined to endorse the then-common target of 1 gram of protein per kilogram of body weight per day (g/kg/day). To do so, they said, would give ‘a misleading impression of precision and finality.’ Instead, they pointed to ‘the lack of precise knowledge of human protein requirements’ and fell back on a rough rule that adults should get at least 10% of their energy from protein.

Fourteen years later, the Ministry of Health (UK) published a report called Requirements of MAN for Protein (1964). In it, they used nitrogen-balance studies, mainly a 1920 review of 109 studies, to estimate the minimum amount of protein required to remain healthy. The committee settled on 0.75 grams per kg of body weight per day (g/kg/day). 

It’s not known why the previous committee didn’t use those data for their protein recommendation. Perhaps they thought it was too old, or they were educated about the issues with nitrogen balance measures. 

Nitrogen balance issues 

Nitrogen balance is a flawed metric for the following reasons: 

• Nitrogen balance assessments tend to overestimate how much nitrogen people consume and underestimate how much they lose through skin, hair, sweat, and other routes, resulting in an artificially positive balance that makes protein needs appear lower than they actually are. 

• When protein intake is restricted, the body also adapts by slowing amino-acid breakdown, so ‘balance’ can be reached at intakes that are not enough to support optimal muscle, immune function or recovery. 

• The relationship between intake and balance is not linear because the body is constantly adapting to its environment. Older studies that assumed it was further underestimated requirements.

• Finally, simply achieving nitrogen equilibrium does not tell us whether muscle protein synthesis, strength or other functional outcomes are being properly maintained. 

These issues have not only just been noticed; scientists in the 1970s pointed out the issues with nitrogen balance in the most prestigious scientific journals, but they were ignored. Better measures are now available.

Newer protein balance measuring techniques

In 2010, a team of researchers reassessed existing nitrogen balance studies using a more accurate measure called Indicator Amino Acid Oxidation (IAAO). They, and other scientists using the same method, found 1.2 g/kg/day to be a more appropriate number for healthy young men, older men and older women. 

A brand-new measure of assessing human protein requirements may also add weight to this evidence. Using stable isotopes to ‘tag’ amino acids before injection, scientists can watch in real-time how quickly they are turned over inside our cells. A 2024 study found the amino acid turnover is almost twice that which had been established using other methods. This doesn’t mean we need to double our protein intake; rather, this translates to a requirement of about 1.0 -1.2 g/kg/day, aligning well with the IAAO method.

Further evidence that the current reference nutrient intake (RNI), the British version of the recommended daily allowance (RDA), for protein is too low comes from a carefully controlled study. Healthy, inactive adults lived in a metabolic ward for eight weeks and were randomly assigned to one of three diets, each providing 40% more calories than needed to maintain their weight. The diets differed only in protein: 0.7, 1.8, or 3.0 g/kg/day. Overeating generally increases lean and fat body mass. Yet the group eating the lowest amount of protein (close to the current RNI) actually lost a small amount of lean (muscle) tissue, while the two higher-protein groups gained more lean mass. 

Based on these and other data, Examine.com, an independent, evidence-based research organisation which is funded by its memberships, recommends 1.2g/kg/day for healthy, sedentary adults. Despite these new data, the inertia of outdated and flawed guidelines has yet to be overcome. 

Protein recommendations remain the same 

Nearly thirty years after ‘Requirements of MAN for Protein’, in 1991, the British Nutrition Foundation (BNF) and Scientific Advisory Committee on Nutrition (SACN) published the same recommendation of 0.75g/kg/day for the ‘general sedentary [adult] population.’ This means consuming roughly 56 grams of protein for men and 45 grams for women, based on average body weights, is deemed sufficient to prevent deficiency. This advice persists today. Preventing deficiency and remaining sedentary are far from optimal. But it may not matter what our official bodies recommend after all.  

How much protein are people actually eating? 

If the goal is simply to avoid protein deficiency and remain sedentary, the official UK figure of 0.75 g/kg/day is the formal threshold, yet even this value is below what is needed for improved health outcomes, as we’ll discuss. In practice, thankfully, most people already eat more than this amount. 

Using the National Diet and Nutrition Survey (NDNS), an online dietary recall from about 4000 people in Britain, estimates are closer to 1g/kg/day. Ignoring the fact that this type of recording is deeply flawed, and accepting that this is the best we have, the British Nutrition Foundation notes that average intakes in the UK exceed the RNI, even among vegetarians, so if people are already getting the benefits of a higher protein diet, there is little pressure on them to alter their advice. Indeed, higher-than-recommended protein intake is associated with various health benefits across many groups. So many groups, in fact, that almost no one remains in the SACN’s and BNF’s sedentary adult group, which, given the healthy benefits of exercise, is a blessing. 

Higher Protein Needs for Specific Populations

Protein during Pregnancy and lactation

Protein needs increase in pregnancy to support growth of the foetus, development of the placenta and expansion of the mother’s own tissues. The European Food Safety Authority recommends an additional 1 g, 9 g, and 28 g of protein per day in the first, second, and third trimesters, respectively. This usually works out at around 1.1g/kg/day later in pregnancy. During lactation, an extra 19 g a day is advised for the first six months of exclusive breastfeeding, falling to 13 g a day thereafter. These figures are based on the nitrogen-balance studies of old, the problems of which we have already addressed. 

When the requirement is measured directly, with IAAO, the picture changes. Stephens, Elango, and colleagues (2015) found that healthy women needed, on average, about 1.2 g/kg/day in early pregnancy (weeks 11–20) and about 1.5 g/kg/day later in pregnancy (weeks 31–38). The upper end of those estimates, the number that covers nearly everyone rather than the average woman, sits around 1.66 g/kg early and 1.77 g/kg late. For a woman of about 70 kg, that is roughly 115–125 g of protein a day, not fifty-odd. Protein demands increase much faster than the bump's size. When breastfeeding, a 2020 study has shown protein requirements are much higher than the recommendations, ranging from 1.7 - 1.9g/kg/day. 

Perimenopause, menopause and postmenopause

Falling oestrogen levels speed up the loss of muscle and bone. Expert groups and growing research point to higher protein intakes of 1.0-1.2 g/kg/day (and up to 1.6 g/kg/day when resistance training is included) to help retain lean mass, support bone and improve body composition. Spreading intake so each main meal provides 25-30 grams of high-quality protein is especially helpful for countering the muscle loss that comes with age and hormonal change. In post menopause, 1.2 - 1.5g/kg/day helps prevent muscle loss and prevent visceral fat from settling around the organs.

Older adults and sarcopenia prevention

Age-related anabolic resistance means older adults need more protein to stimulate muscle protein synthesis properly. The European Society for Clinical Nutrition and Metabolism (ESPEN)—a panel of leading researchers and clinicians specialising in clinical nutrition advice—recommends at least 1.0-1.2 g/kg/day for healthy older adults, rising to 1.2-1.5 g/kg/day and up to 2.0 g/kg/day for those who are malnourished or acutely or chronically ill. Combining higher protein with resistance exercise gives the clearest gains in muscle mass, strength and function, which translates as increased longevity.   

Athletes and highly active individuals

People who train regularly, whether in resistance or endurance, have higher protein needs for muscle repair and adaptation. A major meta-analysis of 49 studies found that protein supplementation improves gains in lean mass and strength during resistance training, with benefits levelling off at roughly 1.6 g/kg/day in young adults. 

Higher intakes, up to 2.0-2.2 g/kg/day, can help advanced trainees or those in an energy deficit, but for most people the returns diminish above about 1.6 g/kg/day. However, a study of forty-eight ‘healthy trained men and women’ showed that consuming 3.4 g/kg/day of protein for eight weeks improved body composition more than the group consuming 2.3 g/kg/day. Interestingly, both groups gained the same amount of muscle mass, but the higher protein group reduced their overall fat mass, despite consuming more energy. The thermic effect of protein digestion can’t account for the entire difference in fat mass between groups, and the authors don’t state their opinions. 

Protein during illness, injury and recovery

During acute or chronic illness, injury, or recovery, protein needs rise due to inflammation, immobilisation, and the demands of tissue repair. ESPEN guidelines recommend 1.2–1.5 g/kg/day for older adults with acute or chronic illness, and up to 2.0 g/kg/day in severe illness, injury or malnutrition. In critical care, the current advice is progressive delivery aiming for around 1.3 g/kg/day, with close monitoring, as very high intakes early on have not consistently improved outcomes.

Table 2: Optimal Protein Requirements 

Table 2.a: Which group is for you?

NB: To get a more accurate idea of how much protein you should be consuming daily, consider what your healthy, leaner body weight should be, not what the scale says. Body mass index (BMI) approximations are close enough for these purposes. Heavily muscled people will need to adjust accordingly. 

Table 2.b: Women. Grams of protein per day 

Table 2.c: Men. Grams of protein per day 

Protein quality metrics (DIAAS, PDCAAS, amino-acid scores)

Protein quality is best judged by how well a food supplies the essential amino acids the body actually absorbs. The older Protein Digestibility-Corrected Amino Acid Score (PDCAAS) method relied on faecal digestibility and could overestimate quality. The newer Digestible Indispensable Amino Acid Score (DIAAS) method measures the digestibility of each individual essential amino acid at the end of the small intestine and is therefore preferred. A DIAAS score of 100 or above means the protein fully meets the requirement for its most limiting essential amino acid, the one present in the lowest amount. Scores below 100 indicate a shortfall in one or more essential amino acids that needs to be compensated for by other foods in the diet.

Animal versus plant protein

For building or maintaining muscle, the priority is a protein source (or mixture) that supplies all the essential amino acids in adequate amounts, with particular attention to leucine. Animal proteins, meat, poultry, fish, eggs, and dairy products are typically rich in essential amino acids, including leucine, and are highly digestible, making them the natural choice. Many are also rich in other micronutrients, the importance of which cannot be overstated in our world of calorie-dense, nutrient-poor convenience foods.  

Most plant proteins contain lower levels of one or more essential amino acids (often lysine, methionine or leucine) and are less digestible in their whole-food form because they’re wrapped up inside fibres. Larger portions or complementary combinations of plant foods are therefore needed to bring the combination up to ‘complete protein’ levels. A 30 g portion of complete protein made from rice and beans typically requires about 1⅓ cups of cooked beans plus 2–2½ cups of cooked rice, delivering roughly 800–850 calories. By comparison, the same 30 g of protein from chicken or whey is only 120–150 calories; the issue here is obvious. Even when the combination is balanced, the total amount of leucine and the sulphur-containing amino acids (methionine and cysteine) remains lower than in an equivalent serving of meat or dairy. 

Setting aside the likelihood of consuming excess calories to meet protein needs, once total daily protein is high enough (~1.2 g/kg/day) and leucine demands are met, well-planned plant-based diets can support muscle protein synthesis similar to that of omnivorous diets.

The main practical difficulties are lower average EAA density and, in whole-plant foods, reduced digestibility due to fibre and antinutritional factors. Also, to match the muscle-protein-synthesis response of animal proteins, concentrated isolates (such as soy, pea or mycoprotein) can be used. These isolates have higher DIAAS scores than most whole-plant foods, but they lack the broad range of amino acids and micronutrients found in meat, eggs, and dairy. Careful meal planning and supplementation throughout the day matter to vegetarians, especially vegans, far more than they do to omnivores. 

In the UK EPIC-Oxford study, average protein intake was 0.91 g/kg in vegan men and 0.99 g/kg in vegan women, above the official RNI of 0.75 g/kg, but below the 1.2 g/kg level that is a more realistic target for maintaining lean mass in sedentary adults. This research, using data from over 30,000 people, is often cited as evidence that plant-based dieters consume enough protein, but once the NRI has been shown to be inadequate, this evidence flips and becomes damning even before we consider the higher targets for special populations.

High protein diet myths

You can’t absorb more than 30 grams of protein in one sitting 

A stubborn idea in gym culture says the body can only use about 30 grams of protein in one sitting and that anything above that is excreted. It’s a tidy story, but in reality it's a misreading of some otherwise good experiments.

Moore and colleagues (2009) gave young men 0, 5, 10, 20 or 40 grams of egg protein after lifting. Muscle protein synthesis rose up to 20 grams and then flattened out; at 40 grams, more of the amino acids were used for energy production. Symons et al (2009) fed young and older adults either 113 grams or 340 grams of lean beef (about 30 versus 90 grams of protein). Over the next five hours, the bigger steak did not drive a bigger rise in muscle protein synthesis. Witard’s study (2014) showed that whey, naturally rich in leucine, triggered MPS at the sweet spot of about 20 grams after a workout. Those papers measured one job, in one tissue, for a few hours. They did not watch the rest of the body. 

If proteins are LEGO, the 30-gram story says any additional bricks go in the bin. They do not. The workshop just works faster. More models get built, more cracked ones get taken apart, and the nitrogen in your urine is the bag of discarded broken bricks, not the new set you just bought. Raise protein, and both synthesis and breakdown rise. That is protein turnover, not waste. The extra urea is the waste product from clearing damaged and oxidised proteins, not proof that lunch has been poured away. Remember, proteins are much more than the building blocks of muscles. 

Amino acids do things that never show up on a muscle-synthesis tracer. They become purines and pyrimidines for DNA and RNA, as well as glutathione, neurotransmitters, creatine, and a long list of other small molecules. The gut and liver take a large first-pass cut and release amino acids over hours, so a big meal is not a single spike that then vanishes.

When researchers extend the measurement window, the expensive urine story disappears. Trommelen and his colleagues (2023) followed people for twelve hours after 25 or 100 grams of milk protein; the larger dose kept muscle protein synthesis higher for longer. MPS didn’t drop off a cliff after the 30 grams was up. Macnaughton et al (2016) had already shown that after a whole-body session, 40 grams of whey beat 20 grams. The old ceiling was an artefact of watching one muscle, after one type of session, for too short a time.

None of this is an argument for swallowing 90 grams at dinner and calling it a day. Spreading 20–30 grams of complete protein across meals is still the practical way to hit the day’s total, keep leucine coming in, and avoid trying to catch up later. Extra protein is not flushed down the loo. Your body will use it as new protein, to recycle parts, or to make other molecules. 

“High-protein diets ‘damage kidneys’.” 

The idea that high-protein diets damage the kidneys is a persistent and damaging myth. Back in 2003, a team of researchers examined high-protein diets in women with normal kidney function and with mild kidney insufficiency, which means a reduced filtering ability measured as estimated (e)GFR. They found that among women with insufficiency, a ‘high intake of nondairy protein’ was statistically associated with a further reduction in eGFR. Those women with normal kidney function remained completely unaffected by the increase in protein. 

The Harvard Gazette headlined those findings as, ‘Too much protein may cause reduced kidney function’, whilst including in the main body of the article the explicit, and less sensational truth, about not being associated with women with normal kidney function. Unhelpfully for millions, the BBC News a few days later published the headline, “High-protein diets ‘damage kidneys’” and warned against the fashionable Atkins diet. At the end of the article, well after most people had given up reading, they quoted ‘Elizabeth Ward, founder and president of the British Kidney Patient Association, [who] said: "If you have healthy kidneys, you can't eat enough protein to damage your kidneys.”’

A few years later, after examining the human data on high protein diets, researchers Martin, Armstrong and Rodriguez (2005) bellowed into the wind, to no avail. They found that whilst protein restriction is a treatment for existing kidney disease, it is not a prevention strategy for healthy kidneys and found no good reason to think high protein initiates kidney disease in people with normal renal function. 

Further meta-analyses of more recent data up to 2018 show the same thing: that kidney function does not change when people eat high protein compared to ‘normal’ and low protein diets.

Is too much protein bad for bones? 

Another myth that is simple enough to stick in our imaginations is that protein leaches calcium from the bones. The idea is that sulphur-containing amino acids make the blood slightly more acidic; the bones release calcium to buffer that acid; the excess calcium appears in the urine, and osteoporosis follows. However, the truth is, as always, more nuanced. It is true that eating more protein raises urinary calcium. That finding is robust. What is not true is that the calcium comes from the skeleton.

When Kerstetter and colleagues (2005) put healthy women on 1.0 versus 2.1 g/kg/day of protein, with calcium held constant, intestinal calcium absorption rose from about 19% to 26%. Urinary calcium rose in lockstep. The extra calcium in the urine was mostly due to calcium coming in from the gut, not calcium leaving the bone. Net bone balance did not change. Later calcium-balance meta-analyses found the same pattern: diet acid load tracks urinary calcium, but it does not track net calcium loss from the body, and it does not meet the criteria for causing osteoporosis. The bone story now runs the other way. 

The International Osteoporosis Foundation (2018) concluded that protein intakes above the official recommendation may reduce bone loss and hip fracture, provided calcium is adequate. A good reason to consume a diverse, whole food diet that is naturally mineral-rich.  

High protein turns into body fat  

When calorie intake is constant, higher-protein diets still improve body composition. When Wycherley and colleagues (2012) pooled 24 randomised weight-loss trials (1,063 adults, about 12 weeks), comparing higher-protein diets (1.07–1.60 g/kg/day) with lower protein diets (0.55–0.88 g/kg/day), the higher protein diets produced more weight loss (about 0.8 kg extra), more fat loss (about 0.9 kg extra), spared about 0.4 kg of lean tissue, better preserved resting energy expenditure, and lowered triglycerides by 0.23 mmol/L. Fasting glucose, insulin, blood pressure and LDL cholesterol did not worsen. The results have been replicated. 

In a randomised controlled-feeding trial, young men in a 40% calorie deficit who ate 2.4 g/kg/day protein gained 1.2 kg of lean mass and lost 4.8 kg of fat over four weeks, whereas those eating 1.2 g/kg at the same energy intake gained almost no lean mass and lost less fat. When calories are matched, the effects are real and repeatable, but modest. If improving your body composition is the goal, aiming for a higher-protein diet to boost satiety and increase or preserve existing muscle mass is a better goal. 

When people are allowed to eat as they please, like in the real world, controlling the appetite is probably the best way to control body weight. Weigle and colleagues (2005) raised protein from 15% to 30% of energy, kept carbohydrates constant, and then let 19 adults eat freely. Spontaneous intake fell by about 440 kcal per day. Over 12 weeks, they lost 4.9 kg, of which 3.7 kg was fat. 

Is there such a thing as too much protein? 

There is no clear practical upper limit for healthy adults. Intakes up to twice the NRI are regularly consumed by active people in Europe and are considered safe. Very high intakes appear safe in the medium term, but long-term data testing diets of about 2.5g/kg/day or above are limited to a single one. 

In 2023, Bagheri and colleagues compared two diets with forty-eight trained men for 16 weeks. One diet had 1.6g/kg/day of protein, the other 3.2g/kg/day. Lean mass, strength, pull-ups, jump height and endurance improved in both groups. However, protein intake of about 1.6g/kg/day did not yield additional benefits except in one area: lower-body peak power. 

People with existing kidney disease should seek medical advice before increasing protein substantially.

Protein Supplementation versus whole-food approaches

Our philosophy matches our physiology: eat real food first. A chicken breast, a steak, eggs, offal, yoghurt or a pint of milk is not just protein; it’s protein sitting inside a matrix of fats, micronutrients, collagen, creatine, haem iron, B12, zinc and, in dairy, calcium. That is the diet you want most of the time.

Supplements exist because life is not gently meandering between meals. Commuting, a grab-and-go lunch, a dairy intolerance, a calorie target you can’t hit with another plate of meat, the cost of convenience, all punch holes in an otherwise decent diet. A protein powder does not outrank the whole food, but it can help you achieve your health goal.

At matched doses of around 30 g of protein, minced beef and milk stimulate muscle protein synthesis about as well as each other over five hours, even if milk is a bit quicker. Isolated whey, because it is fast and leucine-dense, can hit a near-maximal muscle-building signal at a slightly smaller dose, around 20 g in young adults. That is a convenience argument, not a superiority argument. You are not leaving gains on the table by eating the steak. You are leaving nutrients on the table if you replace the steak at every meal with a shake.

Plant isolates can match whey if you take more of them and cobble together any amino acids that are low (lysine or leucine, for example).  That usually means a bigger scoop, a blend, or a leucine-fortified product, and it still will not provide the iron, zinc, B12, or long-chain omega-3s found in animal foods. Isolates are useful, but you can’t live on them. 

Table 3. Common protein powders

NB: DIAAS scores a protein by its weakest digestible essential amino acid against what an adult needs: 100 or above is excellent, 75–99 is good, and below 75 should not carry a protein-quality claim.

Dairy, pea and soya data from Mathai, Liu and Stein (2017).

*Complete beef isolate does not have a single published DIAAS of its own; whole beef sits around 110–116.

Table 4. Whole foods versus a standard scoop

*Complete beef isolate does not have a single published DIAAS of its own; whole beef sits around 110–116.

Practical Next Steps 

1. Use Table 2: Optimal Protein Requirements at your healthy weight to determine your protein goals, not the number on the scales. 

2. Make breakfast protein-dense: 

• Three eggs and 150 g Greek yoghurt (single pot size): about 30–35 grams of protein. 

• Two eggs, wild smoked salmon and a pot of yoghurt: about 35–40 grams of protein. 

• Leftover chicken or beef from last night (the size of the palm of your hand) with an egg: 30+ grams of protein. 

• If you can’t face that at 7 a.m., this is where the complete protein supplement comes in. Our Grass-Fed Beef Protein Powder can be easily stirred into yoghurt or simply had as a drink.

3. Split the rest across lunch, dinner & snacks where appropriate:

• Three meals, each with a proper serving of meat, fish, eggs or dairy, will hit the day for most people in normal-demand ranges. 

• A couple of protein-containing snacks if you train or if lunch was a salad with nothing on it. 

• You do not need to prepare six meals neatly in Tupperware every day like a bodybuilder.

• Ditch the toast or cereal for breakfast before trying to catch up your protein demands at suppertime.

4. Lift something heavy.

• Higher protein diets paired with resistance training is important to achieve most of the benefits discussed throughout this article. 

Conclusion 

The official recommendation of 0.75g/kg/day for protein intake was never about making you well; it was to prevent sedentary people from becoming deficient and ill. If you knew nothing else about protein except that, you would aim higher. For most readers of this article, that means something like 1.2g/kg/day as a minimum; for more active readers or those within one or more of the specific populations, including those in any stage of the menopause and those trying to lose body fat without sacrificing muscle tissue, that number is closer to 1.6g/kg/day. 

Aim to eat real, whole-food sources of protein before taking supplements. Steak, eggs, yoghurt, offal and fish are all incredible sources that come with a host of additional benefits. Pack your breakfast with protein to help you hit your daily goal, then spread the rest fairly evenly across the remaining meals and snacks. If you’re struggling, that’s when supplements really shine. Collagen counts, and comes with a host of its own benefits, but it isn’t a complete protein, so you need to choose one, or more, that are. 

To get the most out of your higher protein diet, start lifting heavy things regularly. This combination protects your muscles from wasting and probably adds good-quality years to your life.

Higher-than-recommended protein diets are not only safe, but healthy. Protein does not cause kidney damage or weaken bones in the presence of calcium from other foods. Nor does it get flushed away when you eat ‘too much’. 

Milo of Croton ate an entire bull; you do not have to do the same to be healthy. But you do have to eat like someone whose body is rebuilding 400 grams of itself before tomorrow morning, which is more than the recommended amount to sidestep deficiency.