A new study from the University of Sydney in Australia looked at how diet can affect ageing. Scientists gave 104 adults aged 65 to 75 all their food for four weeks. Some groups ate a mix of animal and plant foods, while others had mostly plant-based diets. Each group also tried either a higher-fat or higher-carbohydrate diet. The researchers used health tests like blood pressure and cholesterol to measure how well each person’s body was working.

The main reason for the study was to see if eating healthier foods could help the body behave as if it were younger. This is known as improving “biological age.” Biological age shows how well your body works, not just the number of years you have lived. The group that ate mostly animal and plant foods with more complex (whole) carbohydrates and less fat showed the greatest improvement in these health tests.

The main result was that eating healthier foods helped people’s bodies become healthier in only four weeks. However, scientists say this does not mean people actually became younger or will live longer. The study was short, but it showed that better food choices can help older people have healthier bodies.