Short-term dietary changes may reduce biological age in older adults, especially with lower-fat or more plant-based eating patterns.
What if changing your diet for just a few weeks could make your body appear biologically younger? A new study from the University of Sydney suggests that older adults who reduced either dietary fat or animal-based protein showed measurable improvements in biomarkers tied to biological aging after only one month.
Published in Aging Cell, the research focused on adults ages 65 to 75 and examined how different eating patterns affected “biological age” — a measure based on physiological markers rather than the number of years a person has lived. Led by Dr. Caitlin Andrews from the University of Sydney’s School of Life and Environmental Sciences, the study adds to growing evidence that diet may influence how the body ages, even later in life.
While the findings are encouraging, the researchers caution that the results are still preliminary. Longer-term studies will be needed to determine whether these short-term biological changes translate into lasting health benefits or reduced risk of age-related diseases.
What Biological Age Reveals About Health and Longevity
Scientists estimate biological age using biomarker profiles, which track changes in physiological function over time and may provide a better picture of long-term health and life expectancy.
The researchers analyzed 20 biomarkers, including cholesterol, insulin, and C-reactive protein levels, to calculate biological age scores for participants in the Nutrition for Healthy Living study at the university’s Charles Perkins Centre.
The study included 104 participants who were randomly assigned to one of four diets. In every diet, 14 percent of total energy intake came from protein. Two diets were omnivorous, with protein split evenly between animal and plant sources, while the other two were semi-vegetarian, with 70 percent of protein coming from plant sources.
Four Diet Types Tested in Nutrition Study
Participants in both the omnivorous and semi-vegetarian groups were further assigned to either high-fat, low-carbohydrate diets or low-fat, high-carbohydrate diets. This created four diet categories: omnivorous high-fat (OHF), omnivorous high-carbohydrate (OHC), semi-vegetarian high-fat (VHF), and semi-vegetarian high-carbohydrate (VHC).
Participants had BMI (body mass index) scores ranging from 20 to 35. All were non-smokers, non-vegetarians, and free of major health conditions such as type 2 diabetes mellitus, cancer, kidney disease, or liver disease. They also had no food allergies or intolerances.
The OHF group, whose adjusted diet was closest to what participants were already eating before the study, did not show meaningful changes in biological age. In contrast, participants in the other three diet groups showed reductions in biological age scores.
High-Carbohydrate Diet Produced Strongest Results
The strongest statistical evidence for reduced biological age was seen in the OHC group, which followed an omnivorous diet high in carbohydrates. Their diet consisted of 14 percent protein, 28-29 percent fat, and 53 percent carbohydrates.
Researchers do not yet know whether these improvements are temporary or whether they could lead to long-term reductions in biological aging.
“Longer-term dietary changes are needed to assess whether dietary changes alter the risk of age-related diseases,” said Associate Professor Alistair Senior, from the School of Life and Environmental Sciences and the Charles Perkins Centre, who supervised the research.
Researchers Call for Longer-Term Aging Studies
“It’s too soon to say definitively that specific changes to diet will extend your life. But this research offers an early indication of the potential benefits of dietary changes later in life,” said Dr. Andrews.
“Future research should explore whether these findings extend to other cohorts and whether the changes recorded are sustained or predictive of long-term outcomes.”
Reference: “Short-Term Dietary Intervention Alters Physiological Profiles Relevant to Ageing” by Caitlin J. Andrews, Rosilene V. Ribeiro, Alison Gosby, David G. Le Couteur, David Raubenheimer, Jian Tan, Stephen J. Simpson and Alistair M. Senior, 27 April 2026, Aging Cell.
DOI: 10.1111/acel.70507
This study was funded by the University of Sydney, Charles Perkins Centre, and Emeritus Professor George Palmer.
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