By Fatma Younis
High-protein products have proliferated across supermarket shelves, from breakfast cereals to yoghurts, promising benefits for muscle building and healthy ageing. However, experts say the value of extra protein depends on an individual's existing diet and activity level, and more is not always better.
Protein Needs Vary by Individual
Someone who regularly lifts weights may benefit from additional protein to support muscle growth, while an older person with a small appetite might need help reaching adequate intake. Conversely, a person already consuming sufficient protein may gain little from adding more. Understanding these differences can guide decisions about diet changes, supplements, or exercise focus.
Muscle Growth and Protein Intake
Muscle tissue is constantly broken down and rebuilt. Dietary protein supplies amino acids used to make muscle proteins. Resistance exercise — such as weight training or bodyweight exercises like press-ups — stimulates muscle adaptation, and protein supports this process. However, increasing protein intake alone does not replicate the effects of exercise.
A review of 49 trials involving 1,863 participants found that protein supplements produced additional improvements in muscle size and strength during resistance training programmes lasting at least six weeks. The findings highlight protein's contribution to a training programme rather than the effect of adding a shake to an unchanged routine.
Recommended Daily Intake
The UK reference intake for adults is 0.75g of protein per kilogram of body weight per day, equating to about 53g for a 70kg adult. This intake covers the needs of most healthy adults but is not designed to maximise muscle growth. People undertaking resistance training may benefit from higher amounts.
Limits of Protein Benefits
In the same review, additional protein did not appear to produce further gains in fat-free mass — which includes muscle — once total daily intake reached around 1.6g per kilogram of body weight. For a 70kg adult, that corresponds to about 112g from all food and supplements combined. For someone already meeting that threshold, establishing a manageable strength-training routine may be more useful than seeking another high-protein snack.
