How does biological age differ from chronological age?
Chronological age is calendar time since birth. Biological age is a functional estimate of wear and tear. Two people born the same year can sit 20 years apart on cardiovascular and metabolic markers.
Across large cohort studies, biological age predicts cardiovascular disease, type 2 diabetes and all-cause mortality better than chronological age alone.
How is biological age measured?
Epigenetic clocks (Horvath, GrimAge) read DNA methylation patterns and require a lab test. Biomarker panels such as PhenoAge combine blood values like CRP, HbA1c, albumin and creatinine. Functional models estimate age from measurable daily signals: sleep regularity, resting heart rate, VO2max, step count, stress load and substance use.
fjt uses the functional approach. It combines your daily sleep, energy, stress and activity check-ins with step data from your phone to produce an estimated felt age. It is a direction indicator, not a medical diagnosis.
What ages you the fastest?
Chronic sleep debt below six hours degrades insulin sensitivity and immune response within weeks.
Sitting still: under 5,000 steps a day erodes cardiorespiratory fitness and muscle mass, one of the strongest metabolic age predictors.
Sustained stress raises inflammatory markers and is associated with telomere shortening.
Ultra-processed food and alcohol load drive glucose variability and liver burden, which show up quickly in biomarker-based age estimates.
How can you lower your biological age in 30 days?
Week 1 — Anchor sleep: keep bedtime and wake time inside a 30-minute window. Regularity beats duration.
Week 2 — Movement floor: target 7,000-8,000 steps, with a 10-15 minute walk after meals to flatten glucose curves.
Week 3 — Resistance training: two 20-30 minute sessions covering major muscle groups. Muscle is the strongest buffer against ageing.
Week 4 — Recovery: ten minutes of breathwork daily, a screen cut-off time, and one full rest day per week.
Judge the plan on the 8-12 week curve, not on individual days.
How often should you measure?
Daily input improves trend accuracy, but daily verdicts are noise. Meaningful signal appears in four-week averages, which is why fjt foregrounds weekly and monthly curves.
