A new study from the University of Sydney suggests that older adults may be able to improve important signs of aging in as little as four weeks simply by changing what they eat.
Researchers found that people between the ages of 65 and 75 showed signs of becoming biologically younger after reducing dietary fat or eating less animal-based protein. The findings were published in the journal Aging Cell and are adding to growing scientific interest in how diet may influence the aging process.
The researchers stress that the study does not prove people can literally reverse aging. However, the results suggest that certain dietary patterns may improve biological markers linked to overall health and aging much faster than scientists previously expected.
Most people are familiar with chronological age, which refers to the number of years someone has been alive. Biological age is different. It reflects how well the body is functioning internally.
Two people may both be 70 years old, but one person’s body may function more like that of a younger adult while the other may show signs of faster aging. Biological aging can be influenced by many factors, including genetics, exercise, sleep, stress, disease, smoking, and diet.
Scientists often consider biological age to be a better indicator of long-term health than chronological age because it may provide insight into how well organs, metabolism, and body systems are functioning.
To estimate biological age, researchers study biomarkers. These are measurable signs inside the body that reflect health and aging. Examples include cholesterol levels, inflammation markers, blood sugar control, and hormone activity.
For this study, the scientists used 20 different biomarkers to estimate each participant’s biological age. The information came from the Nutrition for Healthy Living study conducted at the University of Sydney’s Charles Perkins Centre.
The study involved 104 healthy older adults. All participants were non-smokers and did not have serious illnesses such as cancer, kidney disease, liver disease, or type 2 diabetes. Their body mass index ranged from 20 to 35.
Participants were randomly assigned to one of four different diet plans. Each diet provided the same overall amount of protein, equal to 14 percent of total daily energy intake. However, the sources of protein and the balance of fats and carbohydrates varied.
Two of the diets were omnivorous, meaning participants ate both animal and plant foods. In these diets, about half of the protein came from animal sources and the rest came from plants.
The other two diets were semi-vegetarian. In those diets, around 70 percent of the protein came from plant-based foods.
Researchers also divided participants into either high-fat, low-carbohydrate diets or low-fat, high-carbohydrate diets. This created four diet groups in total.
The first group followed an omnivorous high-fat diet. The second followed an omnivorous high-carbohydrate diet. The third followed a semi-vegetarian high-fat diet, while the fourth followed a semi-vegetarian high-carbohydrate diet.
After four weeks, the researchers compared changes in biological age markers across all groups.
The group that showed the least improvement was the omnivorous high-fat group. Researchers noted that this diet was closest to what many participants had already been eating before the study began.
In contrast, the other three groups all showed signs of lower biological age after the intervention.
The strongest statistical evidence came from the omnivorous high-carbohydrate group. In this diet, participants consumed lower amounts of fat and higher amounts of carbohydrates while keeping protein intake moderate.
Researchers found that participants in this group showed the clearest reductions in biological age markers.
The scientists believe the results may suggest that lowering dietary fat and reducing dependence on animal protein could improve metabolic health, inflammation, and other processes linked to aging.
Still, the researchers caution that the study lasted only four weeks, which is a relatively short period of time.
It remains unclear whether these improvements would continue over months or years, or whether they would actually reduce the risk of diseases linked to aging such as dementia, heart disease, or cancer.
Dr. Caitlin Andrews, who led the study at the University of Sydney’s School of Life and Environmental Sciences, said the findings should be viewed as an early indication rather than proof that diet can reverse aging.
Associate Professor Alistair Senior, who supervised the research, also emphasized that longer studies are needed to understand whether these dietary changes produce lasting health benefits.
The findings are important because they suggest that even later in life, the body may still respond surprisingly quickly to healthier eating patterns.
Many people assume aging is completely fixed and unavoidable, but scientists increasingly believe lifestyle choices may strongly influence how quickly or slowly the body ages.
The study also supports growing evidence that plant-based foods, lower-fat diets, and balanced nutrition may help improve overall health in older adults.
At the same time, experts caution against making extreme dietary changes without medical advice. Older adults still need enough protein, vitamins, minerals, and calories to maintain muscle strength, immune function, and overall health.
Overall, the study provides encouraging evidence that relatively small changes in diet may positively affect biological markers linked to aging. However, much more research will be needed before scientists can fully understand how diet influences the aging process over the long term.
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The study was published in Aging Cell.
Source: University of Sydney.
