Scientist’s Longevity Self-Experiment Reports Biological Age 15 Years Younger

Highlights

• An ongoing study uses Professor Dean Ho as its single participant to measure real-time responses to fasting, diet, exercise, and sleep.
• The study measures how long it takes for his metabolism to shift from primarily using sugar for fuel to using fat, and it reportedly improved from 24 hours to 16.5 hours.
• The study’s custom AI measurement of biological age (based on how well cells and tissues function) estimated Ho’s biological age at about 32 years (his chronological age is 47).

People typically keep track of their health via annual health screenings, which only give a snapshot of one’s health profile. However, a new study, published in PLOS ONE, from the National University of Singapore (NUS) challenges how we approach health and, more specifically, longevity, by seeking to get a better grasp on what happens between annual health screenings. The study focuses on physiological function, rather than, say, markers from annual blood work, tracking how physiological parameters change moment to moment.

Leading the study is Professor Dean Ho, the director of the Institute for Digital Medicine at NUS. Interestingly, the study has taken a particularly personalized approach: Ho became the study’s only subject.

Named DELTA, the study was designed around the premise that each person has their own biological baseline health status, shaped by factors like exercise, sleep, stress, food, and illness. Accordingly, this baseline shifts with time. To examine how these shifts occur, researchers from NUS introduced a series of lifestyle interventions (varying fasting durations, exercise routines, and nutritional adjustments) all the while monitoring how Ho’s physiology responded in real time.

Dean Ho’s Regimen

Dean Ho’s lifestyle interventions included 20 hours of daily fasting, multiple 48-hour fasts, 90 minutes of strength and cardiovascular training each morning, and a diet centered on leafy greens, seeds, olive oil, and lean protein. Also, beverages were limited to water, liquids containing electrolytes, and black coffee and black tea without milk or sugar.

“We started this study to better understand what happens between annual health screenings, which most people rely on as their measure of health—to look beyond static markers and focus on how the body functions and changes in real time,” said Ho, now 47, in a press release. “We know people are different from each other, but we are also different from ourselves over time. Everyone has their own ‘DELTA’—a unique, evolving set of data that reflects the fact that health is a story, not a snapshot.”

More Details on Ho and Colleagues’ DELTA Study

Ho and colleagues’ DELTA study began in August 2024 and is still ongoing. For the study, Ho wore three wearables—Whoop, Garmin, and Apple Watch—for about eight months. These devices allowed for the tracking of physiological changes over an extended time frame, in contrast to other consumer wearables. It also builds on an earlier 2024 paper in PNAS Nexus that examined Ho’s metabolic shifts over longer periods—from a few hours to about a month.

In the latest study, the researchers captured the body’s ability to undergo metabolic switching in real time over short, minutes-long time frames to reveal how efficiently metabolism responds to short-term stressors (like exercise or calorie restriction). Broadly speaking, metabolic switching refers to the body switching from using sugar to fat for fuel. Easier and faster metabolic switching can often signify better metabolic flexibility (the ability to adjust fuel use to match fuel availability). Metabolic flexibility also deteriorates, on average, with age.

Notable Improvements in the DELTA Regimen

The DELTA regimen induced several notable improvements for Ho:

• For someone in their 40s, like Ho, metabolic switching takes an average of 36 to 72 hours, and sometimes longer, becoming less efficient with older age. Contrastingly, the study showed that Ho’s metabolic switching speed improved from 24 hours at the beginning to 16.5 hours.

• A custom AI program developed by the NUS research team also estimated Ho’s biological age to be around 32, about 15 years younger than his chronological age of 47 years. Furthermore, biological age assessments typically estimate biological age from a single snapshot of molecular or other types of physiological markers, providing an assessment of a person’s cell and tissue function as well as disease risk at a single time point. These approaches offer limited insight into how well the body can respond to and recover from stress. Instead of relying on a single measurement, the AI-powered program used in the study captures physiological responses to stressors in real-time to attain a more advanced measurement of biological age. Accordingly, this advanced measurement purportedly provides a more robust assessment of biological resilience and reveals how quickly the body recovers and adapts.

• Ho’s resting heart rate has improved, as well. It fell from 65 to 46 beats per minute, which can serve as an indicator of more efficient heart function.

• Gut microbiome health (based on the resident microbe composition of the gut) showed positive changes, also. As such, there was no detectable Fusobacterium (a kind of bacteria that can be problematic when enriched) after undergoing a 48-hour water-only fast.

With Their Study as an Example, Ho and Colleagues Hope Individuals Will Engage Meaningfully in Their Own Health Data

With their study as an example, Ho and colleagues hope they will inspire individuals to engage meaningfully with their personal health data to optimize longevity. In doing so, they hope to enable people to make informed lifestyle changes, as opposed to following a generic, one-size-fits-all health-promoting routine.

As an example, the DELTA regimen with its AI-powered measurements builds on, and possibly improves upon, approaches that the longevity field has offered—like biological aging clocks. Most of the current assessments of physiological function based on biological aging clocks rely only on single measurements. Even when AI-powered measurements are added, these measurement techniques often aggregate periodic health readings, rather than capturing how the body adapts in real time.

“DELTA represents a shift toward function-based longevity science by measuring physiological resilience instead of relying on static snapshots,” added Ho. “We hope this work will not only help redefine how healthy aging is understood, but also showcase Singapore’s growing role in pioneering the future of personalized longevity research.”