Privacy Policy

Your health data is among the most personal information you have, and we treat it that way. This policy explains, in plain terms, what WeightLytic collects, where it goes, and the choices you have. We update this policy as features change, and the date above always reflects the latest version.

The short version

WeightLytic is local-first. The data you log — your weight, food, exercise, water, medications and progress photos — is stored on your device, not on our servers. A few optional AI features send the minimum needed to a server to return a result (for example, a meal photo to identify its calories). We never sell your data and never share your individual health data with advertisers.

Data stored on your device

Everything you log in the app is saved locally on your phone (in the app's on-device database): weight history, food and water entries, exercise, GLP-1 / medication tracking, saved meals, and progress photos. We cannot see this data — it does not leave your device unless you use one of the AI features below, or you turn on a backup option. If you delete the app without backing up, this local data is removed with it. Backup is optional and off until you turn it on (see Backup & restore below).

Data sent for AI features

Some optional features need to contact our server to work. When — and only when — you use one of them, we send the minimum needed:

• Food photo & nutrition-label analysis — the photo you choose is sent to our server and on to Google (Gemini) to identify the food and estimate calories and macros. The photo is used to return that result and is not kept on our servers afterwards.
• AI Coach — your question plus the context you choose to share (such as recent weight, calories, medication and goals) is sent to our server and on to Google (Gemini) or OpenAI to generate a reply.
• Barcode & food lookup — a scanned barcode is sent to our server, which checks our food database and, if needed, Open Food Facts, and returns the product's nutrition. Food product data from Open Food Facts is used under the Open Database License.

These providers process the data to return a result to us. We send only what the feature needs, and we do not send your name or contact details with these requests — though an anonymous subscription ID (see below) is included so we can check that your plan covers the feature. If you never use these features, none of this data leaves your device.

Subscriptions & payments

Premium and Pro are sold through the app stores. Your payment is handled entirely by Apple or Google — we never see your card details. To check whether a subscription is active we use RevenueCat, which receives your purchase history and an anonymous subscriber ID created for your installation of the app. That ID is not your name or email, and it is the only identifier sent with requests to our paid features, so we can confirm you are entitled to use them. Deleting the app, or asking us to delete your account, ends this.

Food data sources

Nutrition information for generic and packaged foods is drawn from public food databases: Open Food Facts, used under the Open Database License (ODbL); and McCance & Widdowson's Composition of Foods Integrated Dataset (CoFID), © Crown copyright, used under the Open Government Licence v3.0.

Backup & restore (optional)

WeightLytic offers two optional ways to back up your data, both encrypted on your device before they leave it:

• Encrypted backup file — you can export a single encrypted file and keep it wherever you choose (Google Drive, iCloud, Files, or send it to yourself), then restore from it later. It is encrypted with a passphrase you set; without that passphrase the file cannot be read.
• WeightLytic cloud backup — an optional account (email and password) that backs your data up to our servers automatically. Your data is encrypted on your device before it is uploaded, using a key derived from your password that never leaves your device. We store only the encrypted data and cannot read it. Because of this, a forgotten password cannot be recovered — and neither can the backups it protects. We retain your most recent backups; older ones are automatically removed.

Both options are off until you choose to use them. For cloud backup, the email you register identifies your backup account; you can turn cloud backup off, or permanently delete your account and every backup it holds, at any time from Settings → Backup & restore in the app.

Health Connect (Android)

If you turn on Health Connect sync (off by default), WeightLytic reads and writes your weight entries to Android's Health Connect so your weigh-ins stay consistent with your other health apps and devices (for example a smart scale). This exchange happens on your device through Health Connect; we don't receive that data on our servers. You control it from Settings and from Android's own Health Connect permissions, and you can turn it off or revoke access at any time. We only use Health Connect data to provide the app's features — never for advertising, and we don't share it.

The website & waitlist

If you join our waitlist on this website, we collect the email address (and any name) you provide. We use it only to contact you about the app (for example, when the iOS version launches), and you can ask us to remove it at any time. The website uses minimal, standard server logs.

What we never do

We never sell your data. We never share your individual health data with advertisers. We do not use your data to build advertising profiles.

Security

Data sent to our server is transmitted over an encrypted (HTTPS) connection. Cloud backups are additionally end-to-end encrypted on your device before upload, so we only ever hold data we cannot read. Data stored on your device is protected by your device's own security; the app also offers an optional App Lock (biometric or device passcode) so a shared phone doesn't expose your data. App Lock is a convenience control, not a substitute for full device encryption.

Your choices & rights

Because your logged data lives on your device, you can view, edit or delete any of it directly in the app, and remove all of it by deleting the app. If you use cloud backup, you can permanently delete your account and every backup it holds at any time from Settings → Backup & restore in the app. For data we hold (such as a waitlist email), you can ask us to access, correct or delete it. Email privacy@weightlytic.com and we'll help. See Delete your data for step-by-step instructions.

Children & young people

WeightLytic is rated 13+ and is not directed at children under 13. We do not knowingly collect personal information from anyone under 13; if you believe a child under 13 has given us data, contact us at hello@weightlytic.com and we will delete it. If you are under 18, we recommend using WeightLytic with the support of a parent, guardian or clinician — calorie tracking and weight goals deserve care at any age, and the GLP-1 / medication features are meant for people managing a prescription under a clinician's supervision.

Not medical advice

WeightLytic provides estimates, forecasts expressed as ranges, and general information — not medical advice. It does not make dosing or treatment decisions; always consult a qualified clinician about medication and your health.

Changes to this policy

We'll update this page as the product evolves and revise the date at the top. Significant changes will be highlighted in the app or on this site.

Contact

Questions about your privacy? Email privacy@weightlytic.com.

WeightLytic is operated by Steony Ltd, registered in England and Wales (company no. 17274192).
128 City Road
London
EC1V 2NX
United Kingdom