Higher diet quality is associated with lower odds of biological age acceleration, partially mediated through improved body shape, particularly indicators of central adiposity such as WHtR and BRI.
Each 1-point increase in HEI-2015 score was associated with lower odds of accelerated phenotypic aging.
All four body shape indices exhibited partial mediation effects in the association between HEI-2015 and phenotypic age acceleration.
WHtR and BRI, both indicators of central adiposity, were superior mediators compared to BMI and ABSI in the diet–aging association.
Phenotypic age acceleration was derived from 9 clinical biomarkers as a measure of biological aging.
The study supports a dual-targeted strategy integrating dietary improvement and body shape management to mitigate aging acceleration.
This research suggests that eating a healthier diet is linked to slower biological aging in U.S. adults. The study used data from over 12,500 adults and measured diet quality with a validated scoring tool (HEI-2015) and biological aging using nine blood and clinical markers that can reveal how 'old' a person's body functions relative to their actual age. Each one-point improvement in diet quality score was associated with a 2% lower odds of the body aging faster than expected based on chronological age. The study also investigated why diet quality might affect biological aging, focusing on body shape as a possible explanation. Researchers compared four different ways of measuring body shape — including overall measures like BMI and measures of abdominal fat like waist-to-height ratio (WHtR) and Body Roundness Index (BRI). They found that all four body shape measures partly explained the link between diet and aging, but measures of belly fat (WHtR and BRI) were the strongest mediators, each accounting for roughly 29% of the diet–aging relationship. This means that some, but not all, of the benefit of a healthy diet on biological aging works through keeping central body fat lower. This research suggests that improving diet quality and managing body shape — especially belly fat — together may be a more effective strategy for slowing biological aging than focusing on either alone. Because this was a cross-sectional study (a snapshot in time), it cannot prove that better diet directly causes slower aging, but the consistency of findings across different subgroups and analysis methods strengthens confidence in the association.
Qian Y. (2026). Comparative mediation roles of body shape indices in the association between Healthy Eating Index-2015 and phenotypic age acceleration: A cross-sectional study based on NHANES 2005-2010.. Medicine. https://doi.org/10.1097/MD.0000000000050734