Terms of use
1. Who we are
Nesteia is published by Serhat Dereli, a sole trader based in Bromley, United Kingdom, trading as Nesteia ("we", "us"). You can reach us at serhatdereli@icloud.com. These terms apply to the Nesteia app on the App Store and to this website. By installing or using the app you agree to them. If you do not agree, please do not use the app.
2. Who may use the app
You must be 18 or over. The app asks your age before the timer opens and is rated 18+ on the App Store. Do not use the app if you are under 18, pregnant or breastfeeding, or if a doctor has advised you against fasting.
3. What the app is, and is not
Nesteia is a timer for planned fasting windows and multi-day water fasts, with a ceiling of 120 hours. It shows body stages drawn from published studies of healthy adults, each with a citation and a confidence label, and short reflections in a calm voice. This information is general and educational. It describes what studies measured in other people; it does not describe your body, and it is not medical advice, diagnosis or treatment.
Nesteia is not a medical device and does not monitor, manage or treat any condition. Nothing in the app is a promise about weight, disease, lifespan or any other health outcome. Talk to your GP before fasting if you have any medical condition, take any medication, or have any history of disordered eating, and stop fasting and seek help if you feel unwell.
4. Safety features
The app includes an age gate, screening questions before plans over 16 hours, a risk acknowledgement for plans of 48 hours or more, a 120‑hour ceiling on every fast, a 14‑day gap between fasts of 48 hours or more, and a gap of at least 28 days between fasts that ran over 72 hours. These features reduce risk; they do not remove it, and they are not a substitute for medical supervision. You are responsible for your own decisions about whether, when and how long to fast.
Plans over 72 hours (the 96 and 120‑hour plans) are intended only for people fasting under the supervision of a clinician. Before each such fast the app asks you to confirm that a clinician is supervising it, that your electrolytes are being monitored and that a graded refeed of at least three days is planned, and it records your confirmation with that fast. You are responsible for the truth of that confirmation. The app does not check it and cannot; it relies on you.
5. Free features and Pro
The timer for every daily window, the 24 and 36‑hour plans, custom lengths to 36 hours, body stages to 36 hours, Live Activity, widgets, the History tab with its log of weight, refeed meals and rest weeks, CSV and JSON archive export and the First family of badges are free. Nesteia Pro adds plans and stages beyond 36 hours (including the supervised 96 and 120‑hour plans and custom lengths to 72 hours), with their evidence and what to do, the Strata layers and families beyond the First family, weight trends, and optional iCloud sync.
Pro is sold as an auto-renewing subscription at £4.99 a month or £39.99 a year (with a 14‑day free trial on the annual plan), or as a single lifetime purchase at £99.99. Prices include UK VAT; Apple sets the equivalent price in other storefronts.
- Payment is taken by Apple through your App Store account when you confirm the purchase.
- A subscription renews automatically unless you cancel it at least 24 hours before the end of the current period. You can cancel at any time in your iPhone Settings under your name, then Subscriptions.
- The free trial converts to a paid subscription at its end unless you cancel before then. Cancelling during the trial costs nothing.
- Refunds are handled by Apple under the App Store terms. Ask Apple at reportaproblem.apple.com.
- The lifetime purchase is a one-off payment for the current version of Pro for as long as the app is available on the App Store.
6. Your right to cancel
As a consumer in the UK you have a right to cancel a digital purchase within 14 days, unless you asked for the content to be supplied immediately and acknowledged that you would give up that right. Apple's checkout handles this and any refund; we cannot process refunds ourselves.
7. Your data
Your fasting history, weight entries, screening answers, supervision confirmations and settings are stored on your iPhone. We do not collect them and cannot see them. If you turn on iCloud sync, a Pro setting that is off by default, the same data is also stored in your own private iCloud database under your Apple Account and Apple's iCloud terms; we still cannot see it. You can export your fasts as a CSV file, export everything as a JSON archive you can import on another phone, and delete everything at any time from Settings in the app. See the privacy policy.
8. Using the app
We grant you a personal, non-transferable licence to use the app on Apple devices that you own or are permitted to use, under the App Store terms. You may not copy, modify, reverse-engineer or resell the app, or use it to build a competing product. The app's design, text, badge artwork and the name Nesteia belong to Serhat Dereli.
9. Our responsibility to you
We will supply the app with reasonable care and skill, as the Consumer Rights Act 2015 requires. Nothing in these terms limits our liability for death or personal injury caused by our negligence, for fraud, or for anything else that cannot be limited by law.
Beyond that, we are not responsible for any harm arising from decisions you take about fasting, or from using the app against the guidance in it. We are not responsible for the App Store, for your device, or for events outside our reasonable power to foresee or prevent.
10. Changes and ending the service
We may update the app and these terms. Material changes will be shown in the app or on this page with a new date. We may withdraw the app from the App Store with reasonable notice; if we do, you can still export your history from the installed app. You may stop using the app at any time by deleting it, which removes all of its data from your phone; any iCloud copy can be removed with "Delete everything" in Settings before you do, or from your iCloud settings afterwards.
11. Governing law
These terms are governed by the law of England and Wales, and the courts of England and Wales have jurisdiction, without affecting any rights you have as a consumer in the country where you live.
12. Contact
Serhat Dereli, trading as Nesteia, Bromley, UK. serhatdereli@icloud.com.