‘Gym bros’ may have been right all along — should we all be eating more protein?

The usual public health message on exercise and diet is simple: do enough to avoid trouble. Walk more. Sit less. Get sufficient protein. But that advice, according to a new perspective paper in Frontiers in Nutrition, may be aimed too low for people who want something more ambitious, staying physically capable, mentally sharp, and independent as they grow older.

Dr. Chris Macdonald, a Fellow of Lucy Cavendish College at the University of Cambridge and director of the Better Protein Institute, argues that current guidance is built around minimums, not what newer evidence suggests might help people thrive across the lifespan. In his view, that difference matters.

“Public health advice often focuses on the minimum people need to avoid problems,” Macdonald said. “But many people want to know what they should do to remain strong, independent, and mentally sharp throughout life.”

His paper takes up three plain questions that many people ask but public guidance often answers only partly: How much protein should you have? What exercises should you be doing? And what does the latest science actually suggest?

On exercise, the paper points to a broad body of evidence linking physical activity with lower mortality, better mental health, stronger cognition, better sleep, less fatigue, and greater resilience against age-related decline. The case is not limited to strength or weight control. Exercise, Macdonald argues, is tied to the wider goal of healthspan, the number of years people stay capable and well.

The paper says even modest activity helps. Any physical activity above roughly 15 minutes a day is associated with lower all-cause mortality. But it also argues that the benefits keep rising as weekly activity increases, especially when aerobic exercise is paired with resistance training. In the datasets reviewed, people who did more of both saw particularly strong gains, including an estimated roughly 40% reduction in all-cause mortality.

That is one reason the paper pushes back on the idea that meeting the minimum should be the main public target.

Macdonald also stresses that resistance training should not be treated as optional, especially later in life. Loss of muscle is one of the most visible and damaging features of ageing, linked to frailty, falls, fractures, disability, loss of independence, hospitalisation, and institutionalisation. The paper notes that resistance training is considered the first-line treatment.

The comparison with inactivity is stark. Low muscular strength, the paper says, is associated with about a 200% increase in all-cause mortality risk compared with high strength. Very low cardiorespiratory fitness is associated with about a 400% higher mortality risk relative to high fitness.

The paper also makes a stronger claim that may be less familiar to the public: intensity matters.

Drawing on analyses from the UK Biobank, Macdonald says vigorous activity appears to be far more potent per minute than moderate activity. In those data, vigorous exercise was roughly four times more effective than moderate activity at reducing all-cause mortality risk, and about eight times more effective for equivalent reductions in cardiovascular mortality.

The contrast with light activity was sharper still. According to the paper, more than an hour of light activity may be needed to match the reduction in cancer mortality risk associated with a single minute of vigorous activity.

That does not mean everyone should suddenly start sprinting or lifting heavy weights tomorrow. The paper explicitly notes the need for gradual progression and medical clearance for people who have been sedentary for long periods. But it argues that vigorous exercise should not be treated as something reserved for the young.

In one of the more striking examples, Macdonald highlights research showing that previously sedentary middle-aged adults who completed two years of high-intensity exercise training reversed key structural features of cardiac ageing. The effect sizes, the paper says, were comparable to age-related differences spanning about two decades.

The broad answer to the exercise question, then, is not just move more. It is to build a varied routine that includes cardio, resistance work, and, where appropriate, intensity.

The protein side of the paper makes a similar argument. Current UK recommendations, about 0.34 grams of protein per pound of body weight per day, were designed largely to prevent deficiency in sedentary adults. They were not built to maximise strength, recovery, muscle retention, or long-term function.

Macdonald argues that this older framework still shapes public guidance too strongly.

For active people who do resistance training, the paper says evidence supports intakes well above the UK minimum, in the range of about 0.6 to 1.6 grams per pound per day. It cites research showing that increasing intake from about 0.5 to 0.7 grams per pound per day significantly improved muscle growth, by roughly 30%, and strength, by around 10%.

The same basic pattern appears in other groups. Endurance athletes may need more protein because prolonged aerobic exercise increases amino acid oxidation and muscle protein breakdown. Older adults may benefit from higher intake to help slow or prevent sarcopenia. Pregnant women, the paper argues, may also require substantially more than the current UK minimum to support metabolic demands and fetal growth.

Macdonald also points to a practical question many readers will care about: can higher protein help with fat loss? The paper says yes, in part because protein tends to increase satiety and has a higher thermic effect than carbohydrates or fat, meaning the body uses more energy digesting it. It cites multiple studies in which protein intakes two to three times the UK recommendation helped with fat loss while also protecting muscle.

The paper’s answer to “How much protein should you have?” is not a single number for everyone. But for healthy, active adults seeking what Macdonald calls “optimal health outcomes,” he says a reasonable target could be around 0.7 grams per pound of target body weight per day. For some people, including older adults or those trying to maximise muscle growth, the amount may be at or above 1 gram per pound per day.

The paper does not present higher protein as incompatible with plant-based eating. It argues instead that the issue is planning.

It notes evidence that vegan diets often come with lower protein intake, and that this may help explain some observed risks in specific settings, including fracture risk and some pregnancy outcomes. At the same time, the paper stresses that vegan diets are not inherently low in protein. Foods such as tofu, fortified plant-based products, protein shakes, and carefully combined protein sources can supply all essential amino acids in sufficient amounts.

Macdonald’s point is less about defending one diet identity over another than about quality, quantity, and what he calls the “protein wrapper,” the broader nutritional package that comes with a protein source. A highly processed protein bar may deliver protein, for example, but it may also come with sugars and ultra-processed ingredients. By contrast, foods like tofu or chicken can offer a cleaner route to high protein without excess calories.

That practical framing carries into one of the paper’s core criticisms of current guidance: not just that recommendations are too conservative, but that they are too vague to help people act. Macdonald proposes more direct public tools, including guidance framed as per-meal targets and simple calculators that translate body weight, age, lifestyle, and goals into workable daily plans.

The paper’s central message is that public guidance should distinguish between the minimum needed to avoid deficiency and the level that may support stronger long-term health outcomes.

In practical terms, it answers the paper’s three guiding questions this way: most people should likely do more than the minimum amount of exercise, include both aerobic and resistance training, and treat protein as a key support for training, recovery, and healthy ageing.

It also suggests that exercise advice should move beyond step counts and casual movement toward purposeful training, while protein guidance should become more specific, easier to apply, and flexible enough to work with both omnivorous and well-planned plant-based diets.

Macdonald argues that better communication matters as much as better targets, because people are more likely to act on advice that is concrete, safe, and clearly tied to remaining capable and independent later in life.

Research findings are available online in the journal Frontiers in Nutrition.

The original story "‘Gym bros’ may have been right all along — should we all be eating more protein?" is published in The Brighter Side of News.

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