A yearly medical check can tell you your cholesterol, blood pressure, weight, and blood sugar.
What it cannot easily show is how your body changes during a stressful day, responds to a workout, adapts to fasting, or recovers after poor sleep.
A study from the National University of Singapore is testing whether continuous health tracking can fill in some of those missing details.
The study is called DELTA and is based on a simple idea: human health is constantly moving. A person who looks healthy on a single blood test may respond poorly to physical stress, while someone with similar numbers may recover quickly. Researchers believe these differences in adaptability could provide clues about how well the body is aging.
Professor Dean Ho of the Yong Loo Lin School of Medicine led the project and also became its only research participant. Ho is director of the Institute for Digital Medicine at the National University of Singapore. This allowed his team to collect unusually detailed information about one person over a long period.
The study began in August 2024 and remains ongoing. For around eight months, Ho wore devices from Whoop, Garmin, and Apple. Using several wearables gave the researchers repeated measurements of daily activity, heart function, sleep, and recovery instead of a single reading taken in a clinic.
At the same time, Ho followed a highly structured lifestyle plan. He commonly fasted for around 20 hours per day and sometimes fasted for 48 hours. His mornings included about 90 minutes of strength training or cardiovascular exercise.
His food pattern included leafy greens, seeds, olive oil, lean sources of protein, and other Mediterranean-style foods. He drank water and electrolytes as well as unsweetened black coffee and tea. By combining these interventions with continuous measurements, the researchers tried to see how his body changed in response.
A key measurement was the body’s ability to switch fuels. After eating, the body commonly relies more heavily on glucose for energy. As fasting continues and readily available glucose falls, the body increasingly turns to stored fat.
This ability to move between energy sources is sometimes called metabolic flexibility. Researchers are interested in it because poor metabolic health can make the switch less efficient. Conditions such as obesity and insulin resistance are often associated with problems in how the body manages and stores energy.
In Ho’s case, the time required to make this metabolic shift became shorter. The researchers reported that it improved from more than 24 hours to approximately 16.5 hours. They interpreted this as evidence that his metabolism had become more flexible during the study.
His cardiovascular measurements changed too. Resting heart rate dropped from about 65 beats per minute to 46 beats per minute. In physically fit people, a lower resting heart rate can reflect a heart that pumps blood more efficiently, although a very low rate is not automatically healthier for every individual.
Perhaps one of the clearest lifestyle changes involved sleep. Ho moved his bedtime from after midnight to around 9 p.m. Total sleep increased from approximately five hours to almost eight hours, and the researchers reported more deep sleep and less waking during the night.
The project also examined microbes living in the gut. These organisms interact with digestion, metabolism, and the immune system, although scientists are still learning what defines an ideal microbiome. The researchers reported several changes they considered favorable, including the absence of detectable Fusobacterium in their measurements.
With so many measurements arriving from different sources, the team used artificial intelligence to combine the information. They developed what they call a healthspan copilot, which focuses on how Ho’s body reacted to challenges and returned toward its usual state. This differs from many health systems that mainly compare a person with population averages.
The AI estimated that Ho, who was 47, had a biological age of about 32. Biological age is not the same thing as actual age and has no single universally accepted measurement. It is a model-based estimate intended to describe whether certain features of the body resemble those typically seen in younger or older people.
The researchers argue that a more useful measure of aging may involve resilience. For example, the body can be challenged by exercise, fasting, infection, or lack of sleep. How quickly it adjusts and recovers may reveal weaknesses or strengths that remain invisible when a person is measured only while resting.
The DELTA study was published in PLOS One and follows earlier research published in PNAS Nexus in 2024. The broader aim is to develop a form of personalized health monitoring that uses each person’s own changing baseline instead of assuming that the same target values or lifestyle routines are ideal for everyone.
This approach has some attractive features. Wearables can collect thousands of measurements between medical appointments, potentially showing patterns that a person or doctor would otherwise never see. If these patterns can be linked reliably to future disease risk, they could eventually help people notice meaningful changes earlier.
However, this particular study cannot establish those benefits because it is essentially an intensive case study of one person. Ho’s results tell researchers a great deal about Ho, but very little about how another person would respond to the same routine. Age, sex, genes, medications, fitness, medical conditions, work schedules, and many other factors could produce very different results.
There is also no way to know exactly which intervention caused each improvement. Ho changed fasting, diet, exercise, and sleep while being continuously monitored. Better sleep alone can affect heart rate and metabolism, while intensive exercise can produce its own changes, making it difficult to separate the effects.
The AI-generated biological age is interesting but should not be treated as proof that aging was reversed. Different biological-age tools can give different answers because they use different data and formulas. The most important test will be whether DELTA measurements can predict meaningful outcomes such as disease, disability, recovery, and long-term health in larger groups.
The lifestyle program itself is also too intensive to copy casually. Long daily fasting periods and repeated 48-hour fasts can be inappropriate for some people, and heavy exercise requires adequate nutrition, recovery, and attention to health conditions. A personalized monitoring study should not be confused with a general prescription for healthy aging.
The study’s most valuable message may therefore be less dramatic than the biological-age number but more useful scientifically. Human health is not a still photograph, and continuous measurements can reveal how the body reacts between clinic visits.
DELTA provides an intriguing example of that idea, but larger controlled studies will be needed before anyone can know whether this approach can genuinely extend healthy life.
If you care about health, please read studies about how Mediterranean diet could protect your brain health, and the best time to take vitamins to prevent heart disease.
For more health information, please see recent studies that olive oil may help you live longer, and vitamin D could help lower the risk of autoimmune diseases.
Source: National University of Singapore. Credit: Unsplash+
A yearly medical check can tell you your cholesterol, blood pressure, weight, and blood sugar.
What it cannot easily show is how your body changes during a stressful day, responds to a workout, adapts to fasting, or recovers after poor sleep.
A study from the National University of Singapore is testing whether continuous health tracking can fill in some of those missing details.
The study is called DELTA and is based on a simple idea: human health is constantly moving. A person who looks healthy on a single blood test may respond poorly to physical stress, while someone with similar numbers may recover quickly. Researchers believe these differences in adaptability could provide clues about how well the body is aging.
Professor Dean Ho of the Yong Loo Lin School of Medicine led the project and also became its only research participant. Ho is director of the Institute for Digital Medicine at the National University of Singapore. This allowed his team to collect unusually detailed information about one person over a long period.
The study began in August 2024 and remains ongoing. For around eight months, Ho wore devices from Whoop, Garmin, and Apple. Using several wearables gave the researchers repeated measurements of daily activity, heart function, sleep, and recovery instead of a single reading taken in a clinic.
At the same time, Ho followed a highly structured lifestyle plan. He commonly fasted for around 20 hours per day and sometimes fasted for 48 hours. His mornings included about 90 minutes of strength training or cardiovascular exercise.
His food pattern included leafy greens, seeds, olive oil, lean sources of protein, and other Mediterranean-style foods. He drank water and electrolytes as well as unsweetened black coffee and tea. By combining these interventions with continuous measurements, the researchers tried to see how his body changed in response.
A key measurement was the body’s ability to switch fuels. After eating, the body commonly relies more heavily on glucose for energy. As fasting continues and readily available glucose falls, the body increasingly turns to stored fat.
This ability to move between energy sources is sometimes called metabolic flexibility. Researchers are interested in it because poor metabolic health can make the switch less efficient. Conditions such as obesity and insulin resistance are often associated with problems in how the body manages and stores energy.
In Ho’s case, the time required to make this metabolic shift became shorter. The researchers reported that it improved from more than 24 hours to approximately 16.5 hours. They interpreted this as evidence that his metabolism had become more flexible during the study.
His cardiovascular measurements changed too. Resting heart rate dropped from about 65 beats per minute to 46 beats per minute. In physically fit people, a lower resting heart rate can reflect a heart that pumps blood more efficiently, although a very low rate is not automatically healthier for every individual.
Perhaps one of the clearest lifestyle changes involved sleep. Ho moved his bedtime from after midnight to around 9 p.m. Total sleep increased from approximately five hours to almost eight hours, and the researchers reported more deep sleep and less waking during the night.
The project also examined microbes living in the gut. These organisms interact with digestion, metabolism, and the immune system, although scientists are still learning what defines an ideal microbiome. The researchers reported several changes they considered favorable, including the absence of detectable Fusobacterium in their measurements.
With so many measurements arriving from different sources, the team used artificial intelligence to combine the information. They developed what they call a healthspan copilot, which focuses on how Ho’s body reacted to challenges and returned toward its usual state. This differs from many health systems that mainly compare a person with population averages.
The AI estimated that Ho, who was 47, had a biological age of about 32. Biological age is not the same thing as actual age and has no single universally accepted measurement. It is a model-based estimate intended to describe whether certain features of the body resemble those typically seen in younger or older people.
The researchers argue that a more useful measure of aging may involve resilience. For example, the body can be challenged by exercise, fasting, infection, or lack of sleep. How quickly it adjusts and recovers may reveal weaknesses or strengths that remain invisible when a person is measured only while resting.
The DELTA study was published in PLOS One and follows earlier research published in PNAS Nexus in 2024. The broader aim is to develop a form of personalized health monitoring that uses each person’s own changing baseline instead of assuming that the same target values or lifestyle routines are ideal for everyone.
This approach has some attractive features. Wearables can collect thousands of measurements between medical appointments, potentially showing patterns that a person or doctor would otherwise never see. If these patterns can be linked reliably to future disease risk, they could eventually help people notice meaningful changes earlier.
However, this particular study cannot establish those benefits because it is essentially an intensive case study of one person. Ho’s results tell researchers a great deal about Ho, but very little about how another person would respond to the same routine. Age, sex, genes, medications, fitness, medical conditions, work schedules, and many other factors could produce very different results.
There is also no way to know exactly which intervention caused each improvement. Ho changed fasting, diet, exercise, and sleep while being continuously monitored. Better sleep alone can affect heart rate and metabolism, while intensive exercise can produce its own changes, making it difficult to separate the effects.
The AI-generated biological age is interesting but should not be treated as proof that aging was reversed. Different biological-age tools can give different answers because they use different data and formulas. The most important test will be whether DELTA measurements can predict meaningful outcomes such as disease, disability, recovery, and long-term health in larger groups.
The lifestyle program itself is also too intensive to copy casually. Long daily fasting periods and repeated 48-hour fasts can be inappropriate for some people, and heavy exercise requires adequate nutrition, recovery, and attention to health conditions. A personalized monitoring study should not be confused with a general prescription for healthy aging.
The study’s most valuable message may therefore be less dramatic than the biological-age number but more useful scientifically. Human health is not a still photograph, and continuous measurements can reveal how the body reacts between clinic visits.
DELTA provides an intriguing example of that idea, but larger controlled studies will be needed before anyone can know whether this approach can genuinely extend healthy life.
