What is DayByDay?
DayByDay is a patient-facing wellness tracking application for individuals managing weight loss, frequently in the context of GLP-1 medication therapy. It is a personal tracking tool — not a medical device, not FDA-cleared, and not designed for clinical or diagnostic purposes. All data is self-reported or synced from consumer hardware and should be interpreted accordingly.
The app helps patients stay consistent with logging between appointments, and is organized into five sections: Today (a daily summary dashboard), Track (a manual logging hub for all data types), Nutrition (food and macro logging), Insights (a plain-language AI narrative the patient can flag items from), and You (profile, goals, reports, and settings). The goal is to give patients a clearer picture of their own progress and to facilitate more informed conversations with their care team.
Not a medical device
DayByDay is not FDA-cleared, CE-marked, or approved for diagnostic, clinical decision support, or therapeutic use. Data generated by DayByDay should not be used as the sole basis for clinical decisions. All information should be verified clinically where relevant.
What your patient can track
DayByDay covers the following data categories. All entries are patient-initiated — either logged manually or synced from Apple Health or a compatible wearable.
| Category | What's tracked | Source |
|---|---|---|
| Weight & body composition | Daily weigh-ins, smoothed trend (rolling average of the last 7 entries), body fat %, plus BMI / WHtR / RFM / FFMI estimates and optional DEXA scan values | Manual entry, Apple Health, or patient-entered DEXA results |
| GLP-1 medication | Dose date, medication name, dose amount (mg), week on therapy, injection site (with rotation history), injection pain, notes | Manual entry |
| Pharmacy & refills | Refill cadence, last/next pickup, prior-authorization expiry and reminders | Manual entry |
| Nutrition | Logged foods with macros — protein, fiber, carbohydrate, fat, calories — and daily water intake | Patient-logged via FatSecret database, barcode, photo, label scan, or manual entry |
| Sleep | Total sleep time, stages (REM, core, deep, awake), SpO2, dips per hour, heart rate, respiratory rate, sleep score | Apple Health (Apple Watch), O2 Ring (Wellue/Viatom) |
| Exercise & activity | Daily steps, active calories, exercise minutes, resting heart rate, BMR/TDEE estimates | Manual entry or Apple Health |
| Body measurements | Waist, chest, and neck circumference; clothing sizes | Manual entry |
| Vitals & symptoms | Blood pressure, blood glucose (with meal-time context), mood, and free-text symptom logs | Manual entry (glucose may also sync from Apple Health) |
| Lab values | HbA1c, fasting glucose, total cholesterol, LDL, HDL, triglycerides | Manual entry |
The health report PDF
Your patient can generate a PDF health report from You → Reports & Export. It is designed to be reviewed quickly during an appointment and covers a date range of the patient's choosing.
A typical report includes:
- ✦Weight trend chart — daily weigh-ins with a smoothed rolling-average trend line, total change, and rate of loss over the selected period.
- ✦GLP-1 medication summary — chronological doses with date, medication, amount, and injection site.
- ✦Flagged insights — narrative items the patient bookmarked to raise with you (see below).
- ✦Logged symptoms — free-text symptom and side-effect notes recorded over the period.
- ✦Sleep summary — average total sleep time, stage distribution, average SpO2, and dips per hour where wearable data exists.
- ✦Body measurements — waist, chest, and neck with change from baseline.
- ✦Lab results — HbA1c, fasting glucose, lipid panel, with dates and patient notes.
- ✦Key statistics — BMI, BMR estimate, RFM, WHtR, and FFMI where sufficient data exists.
How flagged insights reach the report
In the Insights tab, an AI coach ("Dayo") generates plain-language narrative summaries of the patient's data. Each card has a bookmark control. When the patient bookmarks a card, that item is collected under "For your provider" and automatically included in the next Health Report PDF, alongside the medication summary and logged symptoms. This is the intended mechanism for a patient to surface the issues they want to discuss — there is no separate compilation step.
Report data is self-reported
All values in the PDF are entered by the patient or synced from consumer wearables. Lab values in particular are self-transcribed and have not been verified against a reference laboratory. The narrative insights are AI-generated from the patient's own logged data. Treat all of it as patient-reported information, not confirmed clinical results.
How to request a report from your patient
Ask your patient to follow these steps before their appointment:
- 1Open DayByDay on their iPhone or at web.mydaybyday.app.
- 2(Optional but recommended) Open the Insights tab and tap the bookmark on any insight they want to raise with you.
- 3Go to You → Reports & Export.
- 4Tap Health Report (PDF) and select a date range (for example, the last 3 months or since their last visit).
- 5Share the PDF via email, AirDrop, or print. Per-table CSV exports are available on the same screen if you prefer raw data.
Suggested date ranges
For a follow-up, a 30- to 90-day report typically provides the most clinically useful view of weight trend, medication adherence, and sleep patterns. The all-time report is useful for evaluating overall progress since the patient began.
Important limitations
Please keep the following in mind when reviewing data from DayByDay.
GLP-1 medication levels are estimates only
The medication level displayed in DayByDay is calculated from pharmacokinetic half-life data using an exponential decay model. It is not a serum drug concentration measurement. Individual variation in absorption, metabolism, renal function, and body composition means actual drug levels will differ from the estimate. Do not use this value for clinical dose adjustments.
Blood oxygen and vitals from consumer devices are not medical-grade
SpO2 readings come from an O2 Ring (Wellue/Viatom) or Apple Watch — consumer optical sensors, not certified pulse oximeters. They may underperform with darker skin tones, poor peripheral perfusion, nail polish, or motion artifact. Blood pressure and blood glucose values are patient-entered (glucose may sync from Apple Health). Confirm any clinically significant finding with a calibrated medical-grade device.
- ✦Weight entries are self-reported and depend on patient consistency and scale calibration.
- ✦Sleep stage data from Apple Watch uses accelerometry and heart rate — it is an approximation, not polysomnography.
- ✦Nutrition macros are drawn from a crowd-sourced consumer food database (FatSecret) and depend on accurate portion selection by the patient.
- ✦Lab values are manually transcribed by the patient from their own results. Cross-reference with your laboratory records.
- ✦Body measurements are self-measured with a tape measure; technique varies between patients.
- ✦AI-generated narrative insights are plain-language interpretations of the patient's own data and are not clinical assessments.
- ✦All calculated metrics (BMI, RFM, WHtR, FFMI, BMR/TDEE) are population-level estimates and should not replace direct body composition measurement in clinical contexts.
Privacy of patient data
Patient data in DayByDay is encrypted in transit (TLS) and at rest (via Supabase PostgreSQL on US-based servers). Row-Level Security policies ensure that no user can access another user's records at the database level.
DayByDay does not share patient health data with third parties for commercial purposes. Third-party processors are limited to: Supabase (database hosting), Anthropic (the relevant slices of patient data are processed to generate the AI coaching narratives — used only to compose those notes, not sold or used for model training or advertising), and RevenueCat (subscription billing status only, not health data). Apple Health data is processed on the patient's device.
Patients retain full ownership of their data and can delete it permanently at any time. DayByDay does not have a HIPAA Business Associate Agreement (BAA) in place and is not designed for use in covered-entity workflows.
No BAA / Not HIPAA-covered
DayByDay does not currently offer a HIPAA Business Associate Agreement. It is designed as a patient-facing consumer wellness application, not a clinical or EHR-integrated tool. It should not be used to store, transmit, or process Protected Health Information (PHI) on behalf of a covered entity.
Clinical questions and contact
If you have questions about DayByDay's data methodology, formula references, or the source of any specific calculation shown in a patient report, we're happy to assist.
Email us at support@mydaybyday.app with "Provider inquiry" in the subject line. Please include the specific metric or calculation in question and we'll respond with the full methodology and any relevant citations.
Important notice for healthcare providers
DayByDay is a personal wellness tracking application and is not intended to be used as a medical device, diagnostic tool, or clinical decision support system. Data generated by DayByDay is self-reported by patients using consumer hardware and software, and narrative insights are AI-generated from that self-reported data. All values, estimates, and metrics should be interpreted in the context of a complete clinical evaluation by a qualified healthcare provider. DayByDay assumes no liability for clinical decisions made based on data presented within the application or its exported reports.