About LYF+

LYF+ is an independent iOS app that turns your Apple HealthKit data into a daily biological age estimate across four science-backed pillars: sleep, activity, recovery, and circadian regularity. It is built and maintained by David Fradel, a solo developer based in France, with no venture capital, no third-party data sharing, and no medical claims beyond what the published literature supports.

Why LYF+ exists

The longevity space over the past few years has split into two extremes. On one side, a handful of ultra-measured personal experiments — Bryan Johnson's Blueprint, David Sinclair's supplement stack, Peter Attia's Medicine 3.0 — with six-figure budgets and medical teams. On the other side, generic wellness apps that track steps and call it a day.

Most people fall in between. They want to know whether their daily habits are actually moving in the right direction. They already own an iPhone and probably an Apple Watch. They do not want another $300 wearable with its own subscription. They do not want a medical claim dressed up as a diagnosis. And they do not want their health data sold to anyone.

LYF+ was built to sit squarely in that middle ground: honest, evidence-based, iPhone-native, and privacy-first. It calculates a biological age estimate every day from the data you already have, using a formula anchored in published longevity research, and it explains every choice it makes.

About David Fradel

David Fradel is the founder, sole developer, and designer of LYF+. He built the app from scratch as a solo project, combining a long background in software engineering with a personal interest in longevity research, circadian biology, and the Apple ecosystem.

David is not a physician. He makes this explicit because E-E-A-T (Experience, Expertise, Authoritativeness, and Trust) matters — especially in health content — and because honesty about what LYF+ is and is not is a core value of the project. LYF+'s scoring formula is not a medical algorithm. It is a transparent, literature-informed estimator that aggregates lifestyle signals into a directional readout.

For medical questions, LYF+ consistently points users toward a healthcare professional. For longevity questions that do not require medical judgment — "am I sleeping enough?", "is my HRV trending in the right direction?", "how close is my bedtime to what the research suggests?" — LYF+ gives a concrete, daily answer.

Editorial principles

The content on this site, including the protocol guides, the biological age explainer, and the FAQ, follows a consistent set of principles:

• Report, do not prescribe. When discussing Bryan Johnson, David Sinclair, or Andrew Huberman, LYF+ reports what they have publicly said or written. LYF+ does not endorse their choices on behalf of readers.
• Avoid medical claims. Phrases like "supports", "may help", or "is associated with" are used instead of "treats", "prevents", or "cures". No disease claims, ever.
• Cite sources. Every substantive claim links back to the original source — peer-reviewed paper, book, or the public communications of the person being discussed.
• Distinguish evidence levels. When the science is strong (e.g., VO2 Max as a longevity predictor), LYF+ says so. When it is weaker or more speculative (e.g., specific supplement effects on lifespan), LYF+ says that too.
• Privacy first. No third-party tracking scripts beyond privacy-respecting analytics in cookieless mode. No selling of health data. No integration with advertising networks. Health data stays on the user's device and in their own secure account.

How LYF+ handles your health data

Apple HealthKit data (sleep, steps, HRV, resting heart rate, VO2 Max, bedtimes) is read from your iPhone locally. LYF+ stores a minimum of derived data — pillar scores, biological age deltas, daily longevity scores — in a secure user account to enable features like trends over time and cross-device sync. Raw HealthKit data is not uploaded.

LYF+ uses analytics (PostHog) to understand how the app is used and to fix bugs. Analytics runs in cookieless mode on the web and with anonymized identifiers in the mobile app. LYF+ does not sell, rent, or share your personal data with third parties for advertising or any other purpose. The full details are in the privacy policy.

Contact

LYF+ is an independent project. If you have feedback, found a bug, want to suggest a feature, or have a press or partnership inquiry, you can reach out via the App Store support channel listed on the LYF+ App Store page.

For content suggestions, corrections to this site, or to flag a claim you think is inaccurate, the same support channel applies. LYF+ takes content corrections seriously and will update articles when credible sources are shared.