A 47-Year-Old Scientist Tracked Himself for Months. His Biological Age Fell to 32

Professor Dean Ho of the National University of Singapore tracked his own body for about eight months as the sole participant in a study he led, called DELTA, which found that his metabolic switching time improved and an AI-powered health copilot developed by his team estimated his biological age at about 32 — nearly 15 years below his chronological age of 47. The findings were published in the peer-reviewed journal PLOS One.

Most people learn about their health from an annual screening, a single snapshot that can miss what happens the rest of the year. DELTA instead tracks how the body functions and changes in real time. Ho varied his fasting periods, exercise routines and nutrition — including roughly 20-hour daily fasts, several 48-hour fasts, 90 minutes of exercise each morning, and a Mediterranean-style diet — while continuously monitoring his physiological responses using three wearable devices: Whoop, Garmin and Apple Watch.

Metabolic switching, which describes how quickly the body moves between using sugar and fat for energy, typically takes 36 to 72 hours or longer in someone Ho's age and often becomes less efficient over time. Over the course of the study, his switching time improved from more than 24 hours to 16.5 hours. His resting heart rate fell from 65 beats per minute to 46, and his total sleep increased from about 5 hours to nearly 8 hours a night.

A custom AI tool developed by the researchers, which tracks molecular and physiological reactions to stress in real time rather than relying on a single set of measurements, estimated Ho's biological age at approximately 32. The study, which began in mid-August 2024, remains ongoing, and the researchers say further work is needed to determine whether the approach can help guide personalized health decisions for others.