Dr. Chris Macdonald, a research fellow at Lucy Cavendish College, University of Cambridge, is challenging the way we think about protein and exercise—not to build bigger biceps, but to preserve the ability to carry groceries, play with grandchildren, and stay sharp well into old age. In a new paper published in Frontiers in Nutrition, Macdonald argues that current public health guidelines, while effective at preventing deficiency, fall short of helping people maximize their healthspan—the number of years lived in good health and independence. Instead of aiming merely to avoid illness, he says, we should be optimizing for resilience, strength, and cognitive vitality throughout life.
The average adult in the UK is told to consume around 0.75 grams of protein per kilogram of body weight daily—a benchmark set to prevent deficiency in sedentary individuals. But Macdonald’s review of recent science suggests that physically active adults, older people, and pregnant women may benefit from nearly double that amount. Studies show that higher protein intake supports muscle maintenance, aids fat loss through increased satiety and metabolic activity, and enhances recovery from physical stress. For a 70kg adult, that could mean increasing intake from 52 grams to as much as 100–140 grams per day, depending on activity level.
Equally important is the type of exercise recommended. While current guidelines emphasize moderate aerobic activity, Macdonald highlights compelling evidence that combining aerobic exercise with resistance training delivers superior long-term benefits. This dual approach not only reduces mortality risk but also strengthens bones, improves balance, and protects against cognitive decline. Yet resistance training remains underemphasized in public health messaging, often dismissed as the domain of bodybuilders rather than everyday health.
One of the paper’s most empowering insights is that high-protein diets don’t require animal products. With thoughtful planning, plant-based eaters—including elite vegan powerlifters and bodybuilders—can meet and exceed optimal protein needs. This reframes high-protein eating not as a fad, but as a flexible, inclusive strategy for lifelong wellness.
Macdonald doesn’t advocate scrapping current guidelines but supplementing them with a new tier of advice: not just the minimum to survive, but the optimal to thrive. He challenges the cultural narrative that frailty in old age is inevitable. “When we see a stereotypical image of a hunched-over, slow, fragile person in ill health in their later years, it seems like an inevitable consequence of 'Father Time,'” he writes. “However, I propose that in most cases, it is evidence of a non-evidence-based lifestyle.” The shift, he believes, could reduce unnecessary suffering on a massive scale—helping people stay strong, mobile, and mentally agile far longer than previously imagined.