How much protein do you actually need? The NHS guideline vs the latest research

Open the NHS Eatwell Guide and the protein number is short and unambiguous: 0.75 g of protein per kilogram of body weight per day. For a 60 kg adult that works out at about 45 g; for an 80 kg adult, around 60 g. The same figure is on the back of UK food packaging as the 50 g “reference intake” for an average adult.

Most nutrition research from the last decade lands somewhere noticeably higher than that — particularly for older adults, anyone doing resistance training, and people trying to lose weight without losing muscle. The gap is not a contradiction so much as a difference in what the two numbers are trying to do. It is worth understanding which question you are actually asking before deciding how much to eat.

Where the 0.75 g/kg number comes from

The UK Reference Nutrient Intake (RNI) for protein was set by the Committee on Medical Aspects of Food Policy (COMA) in 1991 and has been reaffirmed by the Scientific Advisory Committee on Nutrition (SACN) since. It is calculated from nitrogen balance studies: the amount of dietary protein needed so that nitrogen leaving the body (in urine, faeces, skin) is matched by nitrogen coming in. Take the average requirement that puts a healthy adult into balance, add two standard deviations to cover variation between people, and you arrive at roughly 0.75 g/kg/day for the UK and 0.8 g/kg/day for the US Recommended Dietary Allowance.

The important thing about this method is what it is measuring. Nitrogen balance asks one question: how much protein stops a healthy adult from losing lean tissue on average. It does not ask whether the same intake produces the best muscle mass, the best bone density, the best recovery from injury, the best appetite control, or the best preservation of strength into old age. Those are different endpoints, and the protein intake that optimises them is, on the evidence, not 0.75 g/kg.

SACN itself acknowledges this. The 2011 SACN review on dietary reference values for energy and the more recent SACN scoping report on protein both note that the RNI is set to prevent deficiency in nearly all of the healthy adult population, and is not a target for optimal function. Read literally, it is a floor, not a goal.

What the research says for muscle and resistance training

The cleanest piece of evidence on protein and muscle is the 2018 systematic review and meta-analysis by Morton and colleagues in the British Journal of Sports Medicine, which pooled 49 randomised trials of protein supplementation alongside resistance training. Two findings have shaped practice since:

• Extra protein clearly increased strength and lean mass on top of training alone, but the benefit plateaued at around 1.6 g/kg/day (with a 95% confidence-interval upper bound near 2.2 g/kg). Eating more than that did not produce further gains in healthy young adults.
• The effect was larger in trained people than in beginners, and larger in older adults than in younger ones — which fits the broader picture that the older you are, the more protein you need to get the same muscle-building response.

Phillips and colleagues, who have written most of the influential reviews in this area, have made the same point repeatedly: for someone doing resistance training, the RNI is roughly half of what the evidence supports. The International Society of Sports Nutrition’s 2017 position stand recommends 1.4–2.0 g/kg/day for physically active people, and notes higher intakes can be useful during fat loss to preserve lean mass.

What the research says for older adults

The argument is sharpest in older adults, because two things change with age. Anabolic resistance: the muscle-building response to a given amount of dietary protein weakens. And sarcopenia: the progressive loss of muscle mass and strength that drives a large share of falls, fractures, and loss of independence later in life. Eating the RNI in your seventies is not the same proposition as eating it in your twenties.

The 2013 PROT-AGE consensus from an international expert group (Bauer et al., JAMDA) recommended 1.0–1.2 g/kg/day for healthy older adults, and 1.2–1.5 g/kg/day for those who are acutely or chronically ill. The European Society for Clinical Nutrition and Metabolism (ESPEN) expert group published essentially the same numbers in 2014, with the additional point that protein should be spread across the day’s meals rather than loaded into a single evening dose — older muscle responds best to roughly 25–30 g of protein per meal containing a decent leucine load.

These are not fringe recommendations. They are the standard clinical-nutrition position for people over about 65, and the gap between them and the NHS RNI is large: a 70 kg retiree eating to the RNI is taking about 52 g of protein a day, while the PROT-AGE midpoint puts them closer to 77 g.

What about weight loss and appetite?

Higher-protein diets have a small but consistent edge in controlled weight-loss trials: greater satiety per calorie, better preservation of lean mass on an energy deficit, and a modest thermic-effect advantage. Reviews from Leidy and colleagues (American Journal of Clinical Nutrition, 2015) and subsequent meta-analyses through 2023 put the useful range for someone losing fat at roughly 1.2–1.6 g/kg/day of actual body weight — or about 2.3 g/kg of fat-free mass in trained dieters. The mechanism is not glamorous: more protein, eaten across meals, makes it easier to stay in a deficit without losing the muscle you would otherwise burn for fuel.

Is there an upper limit to worry about?

For healthy adults with normal kidney function, no. The idea that high-protein diets damage kidneys originated from studies in people with existing chronic kidney disease, where protein restriction is a clinical tool. In people without kidney disease, randomised trials and long-term observational data — including reviews by Devries et al. (2018) and Kamper & Strandgaard (2017) — have not shown a causal link between higher protein intake and renal harm. The Institute of Medicine’s acceptable macronutrient distribution range goes up to 35% of energy from protein, which for most people sits well above 2 g/kg.

The genuine exceptions: established chronic kidney disease (where intake should be set by a renal dietitian), and certain rare metabolic disorders. For everyone else, the ceiling that matters is practical — getting protein in without crowding out the rest of a varied diet.

Putting it together

Read against the modern literature, the NHS 0.75 g/kg figure is best understood as the lower bound of healthy intake for a sedentary adult — the amount that keeps an average healthy person out of deficiency. The intake that actually optimises muscle, recovery, satiety, and healthy ageing is consistently higher:

• Sedentary, healthy adult: 0.8–1.0 g/kg/day is a reasonable everyday target, sitting comfortably above the RNI floor with no downside.
• Resistance-training adult: 1.4–2.0 g/kg/day, with the Morton meta-analysis plateau at about 1.6 g/kg.
• Adult on a fat-loss diet: 1.2–1.6 g/kg/day of body weight, weighted to higher in the range if you are also lifting.
• Older adult (65+): 1.0–1.2 g/kg/day if healthy; 1.2–1.5 g/kg/day during illness, recovery, or chronic disease. Spread across meals.

Most adults can hit these numbers from food alone — eggs, dairy, fish, meat, soy, pulses, and whole grains do most of the work, and there is nothing the powder does nutritionally that a chicken breast does not. A whey or plant-protein supplement is a convenience product: it makes it easier to add 20 g of protein to a breakfast or a post-training meal without cooking. That is a real benefit if you are short on time or appetite, and irrelevant if you are not.

If you do use a protein powder, the practical risk is not the protein itself but what else can end up in a tub. Protein powders have repeatedly been flagged for heavy-metal contamination, undeclared ingredients, and (in sport) substances on the WADA banned list. A third-party certification — Informed Sport, Informed Protein, or NSF Certified for Sport — means the specific batch has been independently screened for contaminants and label accuracy.

You can browse third-party-tested protein products on Certwell or read more about how each certification compares.