Professor becomes his own test subject in longevity study, with biological age estimated 15 years younger

A professor at the National University of Singapore has spent years tracking his own health in an unusual longevity experiment, using continuous physiological data to explore how lifestyle changes affect the body in real time.

Professor Dean Ho, director of the Institute for Digital Medicine at the Yong Loo Lin School of Medicine, became the sole participant in a study called DELTA. The project is based on the idea that health cannot be fully captured by an annual medical check-up. Instead, the researchers wanted to observe how a person's body responds to stress, diet, exercise, sleep and fasting as these factors change over time.

The study began in August 2024 and is still ongoing. Ho, who was 47 when the study was conducted, followed an intensive lifestyle program that included approximately 20 hours of fasting each day, several 48-hour fasts, and around 90 minutes of strength or cardiovascular exercise every morning.

His diet was based largely on Mediterranean-style foods, including leafy greens, seeds, olive oil and lean sources of protein. His regular beverages were limited to water, electrolytes, black coffee and unsweetened black tea.

The researchers monitored his physiological responses using three wearable devices—Whoop, Garmin and Apple Watch—for approximately eight months. The study was designed to capture changes that conventional health screenings and standard wearable reports may miss.

Faster metabolic switching

One of the main findings involved metabolic switching—the body's ability to move between using glucose and fat as sources of energy.

For people around Ho's age, this metabolic transition can take between 36 and 72 hours or longer and may become less efficient with age.

During the study, however, Ho's metabolic switching time improved from more than 24 hours to 16.5 hours, suggesting greater metabolic flexibility.

The researchers also developed an artificial intelligence health copilot that analyzed his molecular and physiological data. The system estimated Ho's biological age at approximately 32, around 15 years younger than his chronological age.

The researchers emphasize that biological age estimates are usually based on a snapshot of molecular or physiological markers. Such measurements provide information about a person's health status and disease risk but may not show how effectively the body responds to stress or recovers afterward.

The DELTA approach instead focuses on real-time responses, using changes in physiology to assess what the researchers describe as biological resilience—how quickly the body adapts to challenges and returns toward its normal state.

Improvements in heart rate and sleep

The study also recorded several other changes.

Ho's resting heart rate fell from 65 to 46 beats per minute, which may indicate improved cardiovascular efficiency and recovery.

His sleep pattern also changed significantly. He began going to sleep around 9 p.m., compared with after midnight previously. Total sleep increased from approximately five hours to almost eight hours, while the amount of deep sleep increased and nighttime wakefulness decreased.

The researchers also observed changes in the gut microbiome. Fusobacterium was not detected in any of the measurements, while other findings suggested improved energy conservation during certain fasting periods.

A different approach to healthy aging

The researchers say DELTA is intended to demonstrate the potential of personalized, data-driven approaches to longevity rather than prescribe a universal lifestyle routine.

According to Ho, people differ not only from one another but also from themselves over time. Factors such as stress, sleep, nutrition, exercise and illness can continuously alter an individual's physiological baseline.

The study therefore aims to shift longevity research away from isolated measurements and toward continuous monitoring of how the body functions, adapts and recovers.

The researchers hope that this approach could eventually help people make more informed lifestyle decisions based on their own physiological data rather than following generic recommendations.

The study, “DELTA: Strengthening human biological resilience with an N=1 digital health and dynamic biomarker protocol,” was published in PLOS One. The research is ongoing.