A diet swap can make you biologically younger, at least in the short term. Australian researchers found that adults in their late 60s and early 70s showed measurable signs of reduced biological age after just four weeks of changing what they ate.
The study, published in Aging Cell, tracked 104 people between 65 and 75 as they followed different eating patterns. Some cut back on fat. Others shifted away from animal protein toward plants. The results surprised even the researchers: three of the four diet groups showed improvements in the biological markers that predict aging and disease risk.
The strongest effect came from participants who ate an omnivorous, high-carbohydrate, low-fat diet. That group showed the clearest reduction in what scientists call biological age, a measure of how well the body is actually functioning rather than how many years a person has lived.
Biological age matters because it reflects the body's real condition. Two 70-year-olds can have vastly different biological ages depending on health, lifestyle, and how well their body recovers from stress. Scientists measure this using biomarkers like cholesterol, insulin, and inflammatory proteins that signal disease risk and longevity.
The research team, led by Dr. Caitlin Andrews at the University of Sydney's School of Life and Environmental Sciences, used 20 different biomarkers to calculate each participant's biological age. The only group that showed no improvement was those who stayed closest to their original eating patterns.
All study participants received 14 percent of their daily calories from protein. The diets differed in whether that protein came mostly from animals or plants, and whether the rest of the calories came from fat or carbohydrates. Participants had BMI scores between 20 and 35 and no serious health conditions before the study began.
The breakthrough is tantalizing, but researchers are cautious. Four weeks is not long enough to know whether these changes stick around or actually prevent disease. Associate Professor Alistair Senior, who supervised the work, said longer studies are needed to understand whether dietary shifts actually reduce the risk of age-related illness.
Andrews echoed that caution: "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."
The team plans to investigate whether the findings hold up in other groups and whether the biological improvements seen at four weeks persist over months or years. They also want to know if the same diet shifts benefit younger adults.
Author Jessica Williams: "A four-week diet change reversing aging markers is remarkable, but the real test is whether these shifts last and actually keep people healthier down the road."
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