When Dr. Morgan Levine’s father walked her to school, people were convinced he was her grandfather. She was born when he was 54, a retired actor who took on the role of primary caregiver at home. Even though he was always active and energetic, she worried he would not be around for many years. To her relief, he stayed by her side for more than 30 years — during which she channeled that fear into studying gerontology, eventually becoming a senior lecturer and researcher at Yale University.
Her main area of expertise is the attempt to “stop time” by developing tools to measure biological age — our “real” age, based on the actual condition of the body’s systems — and to understand how aging can be slowed, or even reversed.
The field of longevity — the science of extending healthy life span — has generated enormous hype over the past decade. Some of it is justified and scientifically grounded; some of it is more promotional, driven by biohackers, often wealthy, who experiment on their own bodies with every new gadget and esoteric method in the hope of staying young forever.
Dr. Levine, 41 (biological age: 36), has in recent years expanded her work into more practical, industry-facing directions, bringing a measured, sober voice whose core message is expressed in her book "True Age". She argues that we should all take greater interest in our biological age, try to measure it — there are already inexpensive ways to do so — and act to improve it.
“By understanding and tracking our personal aging process,” she writes, “we can discover ways to delay aging, adopt habits that support us, decide whether to seek medical advice before illness develops, and take responsibility for our health and well-being while enjoying our chronological time on Earth.”
Before that, however, a few words about the aging process itself. Most scientists agree that aging begins at the molecular level, driven in part by accumulated DNA damage, the buildup of defective proteins and metabolic disruptions that cause “cellular exhaustion.” Over time, these changes lead to age-related phenomena: disease, functional decline, wrinkled skin, loss of muscle mass, reduced athletic performance, abnormal lab results and more.
Research shows that the consequences of molecular aging processes are detectable very early in life, but because of the body’s resilience, we rarely notice them. The body can absorb a certain amount of damage and continue to function without obvious signs of trouble. When damage accumulates to a more severe level, physiological and anatomical changes begin to appear, eventually limiting physical and cognitive function.
Levine’s extensive research on biological age — a measure of how we are actually aging — has produced several encouraging findings. One is that only about 10% to 30% of life expectancy is influenced by genetics, which ranks only third among the factors affecting biological aging. The top factor, by far, is our health-related behavior: physical activity, diet, sleep and habits. Second are life circumstances and the stresses they entail. In other words, even with problematic genetics and difficult life conditions, the primary control over our aging lies in our own hands.
How to measure your biological age
Before changing lifestyle habits, it is important to know the body’s current state. Rather than focusing on a specific disease or function, Dr. Levine proposes a holistic perspective, viewing aging as a multisystem process. Biological age, therefore, reflects different rates of aging across different body systems over time.
Scientists, Levine acknowledges, still do not agree on the best method for estimating biological age — from simple approaches like facial photography to complex, multisystem assessments requiring advanced technology and significant expense. Still, there are several ways to begin estimating our true age.
In the early 2000s, geriatrician Dr. Kenneth Rockwood and applied mathematician Dr. Arnold Mitnitski demonstrated that an individual’s aging process can be reliably estimated by calculating the ratio between the number of possible deficits and the deficits actually present. They found that this measure — which they called the frailty index — increases steadily over the life course and serves as a strong indicator of remaining life expectancy, beyond chronological age. It reflects functional aging and is considered a good predictor of future vulnerability to disease and mortality.
Another advantage is its simplicity: unlike many other measures, it is easy to calculate, entirely noninvasive and does not require data beyond what already appears in a standard medical record.
A somewhat more complex index published by Dr. Levine in 2018 combines multidimensional information from laboratory tests reflecting the function of different body systems. Nine blood markers, selected from a panel of nearly 50 possible tests, are mostly included in routine annual checkups. Together they capture physiological states across systems including cardiovascular, immune, liver, kidney and metabolic function. They were selected using machine learning as the combination that best predicts lifespan (details and example websites for data entry appear below).
Beyond these measures, Dr. Levine is deeply involved in developing more advanced, less accessible tools, including epigenetic clocks — measurable biological instruments based on chemical changes in DNA (methylation), assessed through blood or saliva samples. Methylation research has shown that chemical tagging patterns across the genome change significantly with age. The first methylation-based biological age measure was published in 2011 by researchers at UCLA. In 2014, one of those researchers, Dr. Steve Horvath, developed the eponymous clock that became a central tool in biological age assessment. Levine later collaborated on studies refining this clock, and in 2019 launched a product called “Index,” allowing people to collect saliva samples at home and send them to a lab to determine biological age.
How to make your biological age younger
Once biological age has been measured and understood, it is possible to influence it through lifestyle changes.
Nutrition:
Various forms of caloric restriction have been scientifically shown to extend both lifespan and health span by reducing metabolic load and chronic inflammation. Because long-term restriction is difficult to sustain, Levine recommends more feasible approaches such as intermittent fasting for several hours a day or a fasting-mimicking diet — typically 500 to 700 calories a day for five consecutive days, once a month or several times a year. In a study she conducted with a colleague, three cycles of a fasting-mimicking diet over several months reduced biological age by an average of about two and a half years. Simulations suggested this could significantly reduce disease burden and premature mortality if practiced annually — about 15 days of moderate fasting per year.
Additional dietary advice includes eating two structured meals a day (even without fasting), avoiding snacking, reducing sugar, white flour and ultra-processed foods, and paying close attention to how the body responds, not only to what is considered “healthy.” The dietary patterns she most strongly endorses are the Mediterranean diet and a largely plant-based diet with moderate meat consumption.
Physical activity:
Research shows that regular, moderate exercise reduces biological age more effectively than extreme, inconsistent training. The ideal combination includes aerobic and strength training, tailored to individual needs and abilities. Another key recommendation is not to “train until breakdown”: while moderate physical stress benefits health, excessive stress ultimately causes damage and accelerates aging. Levine suggests starting with free, enjoyable activities such as a daily 30-minute walk to improve cardiovascular health, preserve muscle mass and strengthen bones. Her own chosen activity is horseback riding five days a week.
Sleep and stress management:
This is a central pillar of longevity and health span. The optimal amount is about seven hours of sleep per night. Studies show that fewer than five hours of sleep is associated with reduced life expectancy, while excessive sleep is also a significant mortality risk factor. Improving sleep quality should go hand in hand with managing chronic stress through breathing techniques, reducing sustained overload and setting boundaries at work.
Check yourself: what is your frailty index?
1. Have you ever been diagnosed with any of the following?
Score: one point for each “yes”
- Type 2 diabetes
- Heart failure
- Ischemic heart disease
- Angina
- Heart attack
- Atrial fibrillation
- Stroke
- Cancer (one point per type)
- Emphysema
- Chronic bronchitis
- Chronic obstructive pulmonary disease (COPD)
- Liver disease
- Dementia
- Arthritis
- Osteoporosis
- Hearing impairment
2. How difficult is it for you to perform the following without help or special equipment?
Score: 0 – not difficult, 0.5 – somewhat difficult, 0.75 – very difficult, 1 – unable
- Walk half a kilometer
- Climb 10 stairs
- Bend, stoop or kneel
- Lift or carry 5 kg
- Walk between rooms
- Rise from a chair without armrests
- Get into or out of bed unaided
- Grip kitchen or work tools requiring fine motor control
- Stand for more than half an hour
- Raise your arm overhead
- Remember what you ate for dinner yesterday
- Walk on uneven ground without falling
3. Blood tests: are your values within the following ranges?
Score: one point for each “yes”
- Triglycerides of 150 mg/dL or higher
- HDL (“good”) cholesterol below 40 mg/dL
- LDL (“bad”) cholesterol above 160 mg/dL
- Systolic blood pressure of 130 mmHg or higher
- Blood glucose of 100 mg/dL or higher
- Albumin below 3–4 g/dL
Summary:
Add the points from all three categories and divide by 34. If some answers are unknown, add what you know and divide by the number of answered items.
- Below 0.1 – very fit
- 0.1–0.2 – healthy
- 0.2–0.3 – functioning
- 0.3–0.4 – vulnerable
- 0.4–0.5 – mildly frail
- 0.5–0.6 – moderately frail
- 0.6 and above – severely frail
Lab tests for multisystem aging
Most of the following tests used to calculate phenotypic age (multisystem aging) are standard. After receiving results, they can be entered into free online calculators, such as the site longevityadvantage.
- Fasting glucose – metabolic function
- C-reactive protein (CRP) – inflammation level
- Serum albumin – liver function and nutritional status
- Alkaline phosphatase (ALKP) – liver function
- Serum creatinine – kidney function
- Red blood cell distribution width (RDW) – immune system
- Lymphocyte percentage – immune system
- White blood cell count (WBC) – immune system
- Mean corpuscular volume (MCV) – immune system