Analysis of 157,457 UK Biobank participants found that higher adherence to the Eatwell Guide—Britain's official dietary recommendations—was associated with preserved muscle mass, slower grip strength decline, and reduced falls risk over time. The diet emphasizes fruits, vegetables, whole grains, and lean proteins while limiting processed foods and saturated fats. This represents one of the largest investigations linking national dietary guidelines to objective measures of physical aging. The findings suggest that following established dietary patterns may meaningfully slow musculoskeletal decline, particularly relevant as muscle mass naturally decreases 3-8% per decade after age 30. The protective effect against falls—a leading cause of injury in older adults—remained stable throughout follow-up, indicating sustained benefits. However, the walking pace advantage diminished over time, suggesting some functional benefits may plateau. As an observational study, it cannot establish causation, and self-reported dietary data introduces potential bias. Importantly, this preprint awaits peer review, so results may change. Still, the consistency across multiple physical function markers and the large sample size strengthen confidence in these associations, supporting the Eatwell Guide as a practical framework for healthy aging.