Only Fasting
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KVKK Disclosure Notice

Law No. 6698 on the Protection of Personal Data, Article 10

Last updated: October 18, 2026

1. Data Controller

Data Controller: Mustafa Baykal (Individual App Developer)

Email: privacy@onlyfasting.com

Address: Istanbul, Türkiye

App: Only Fasting (iOS / Android)

This disclosure notice has been prepared pursuant to Article 10 of Law No. 6698 on the Protection of Personal Data ("KVKK") to inform you about how your personal data is processed.

2. Personal Data Processed

2.1 Identity and Contact Data

Data TypeExamplesMandatory?
Email addressFor account creation and sign-inYes (for an account)
Full nameProfile personalizationYes
Password (hashed)AuthenticationNo (sign-in with OAuth is possible)

2.2 App Usage Data

Data TypeExamplesMandatory?
Fasting dataStart/end times, fasting plan, streak informationYes (core functionality)
Water intake dataAmounts of water consumed, timestampsYes (core functionality)
Check-in dataHunger, energy, mood, symptomsYes
Meal logsFood names, calories, macronutrientsNo (optional)
PreferencesLanguage, notification settings, time zoneYes
Device informationDevice model, OS version, and a device ID generated by the app (on Android, the app-scoped Android ID)Yes (for the app to work)

2.3 Health and Body Data (Special Category)

Data TypeExamplesMandatory?
Body measurementsWeight, height, body mass index (BMI)No (optional)
Nutrition dataCalorie intake, protein, carbohydrate, and fat valuesNo (optional)
Activity dataExercise type, duration, calories burnedNo (optional)
Movement screening and session dataReported pain and body region, joint limitations, doctor restriction, pregnancy or postpartum indicator, body measurements, readiness responses, effort rating, session history, and rule reason codesRequired when the Movement feature is used
Health platform data (Apple Health / Health Connect)Supported steps, active energy, workouts, weight, height, sleep, and resting heart-rate dataNo (optional, off by default)
Momo Coach chat dataThe messages you write to Momo Coach, Momo's answers, and the record summary sent to the AI model with each message (Section 6.6)No (optional; Premium users aged 18 or older, with separate explicit consent)

Important: The Movement feature asks the user to accept the Movement information shown; the version and date of the acceptance are recorded. The account-level AI-processing setting is recorded separately. The core fasting timer and the water reminder can be used without the Movement and AI features.

2.4 Data Not Collected and the Optional iOS Exception

We do not collect the following data; the stated iOS permission-based exception applies to measuring and optimizing Only Fasting ad campaigns:

- Location information

- Address book / contacts

- Biometric data (stays on the device, is not sent to us)

- Android Advertising ID is not collected. On iOS, only if you allow tracking in the iOS prompt, the device advertising identifier (IDFA) is shared with Meta to measure and optimize Only Fasting ad campaigns.

- Cross-app tracking data is not collected, except that the device advertising identifier and install, app-open and session events are shared with Meta to measure and optimize Only Fasting ad campaigns only with iOS tracking permission.

The purpose of optional Meta ad measurement on iOS is to measure and optimize Only Fasting ad campaigns through install, app-open and session events. The stated legal basis for this processing is your explicit consent given via the iOS tracking permission, separate from usage analytics and health consent. Only with this permission, the device advertising identifier (IDFA), install, app-open and session events, and device model, OS and app version, language/locale, time zone, screen size, carrier/network information (including IP address), and the SDK's own anonymous app-install ID are transferred to Meta Platforms Ireland Ltd. / Meta Platforms, Inc. These data are transferred abroad, to Ireland and the USA, on the same consent. Only Fasting does not pass health, meal or coach-chat content, account IDs, email addresses, or subscription and purchase events to the Meta SDK. Automatic content and purchase logging are disabled. Refusing leaves the app usable and does not initialize this measurement SDK. You can withdraw permission in iOS Settings → Privacy & Security → Tracking.

3. Purposes of Processing Personal Data

4. Processing Grounds and Product Controls

Processing ActivityStated Ground or Current Product ControlArticle or Record
Account creation and authenticationPerformance of a contractArticle 5/2(c)
Fasting and water tracking (core features)Performance of a contractArticle 5/2(c)
Processing of health/body and Movement screening dataThe Movement information/acceptance is recorded with its version and dateThe account-level AI-processing setting is recorded separately
Apple Health / Health Connect data reading/synchronization and optional writingThere are separate app controls for reading/synchronization and for writing/exportThe related operating-system permissions are also required and can be revoked in the system settings
AI food, activity, and weekly analysisBefore a food-text, food-image, or activity request, the mobile client checks the account's AI-processing settingThe weekly server process sends a Gemini request only while the account value is true
Sending notificationsLegitimate interestArticle 5/2(f)
Analytics and app improvementOn by default, can be turned off in the settingsCan be turned off under Profile > Privacy & Data > Usage Analytics
Crash reportingOn by default, can be turned off in the settingsCan be turned off under Profile > Privacy & Data > Crash Reporting
Subscription transactionsPerformance of a contractArticle 5/2(c)
Transfer of data abroadThe transferred fields and recipients are listed in Sections 6-8For Gemini, the account-level AI-processing setting is used
Momo Coach chat and encrypted chat recordSeparate explicit consent for the health-related information and the transfer to our AI providers listed here (recorded with version and date); legitimate interest for security and preventing misuse; for keeping the record after consent is withdrawn or the account is deleted, the establishment, exercise, or protection of a rightArticle 6 and 9 (explicit consent); Article 5/2(f); Article 5/2(e)
Optional iOS Meta measurement and optimization of Only Fasting ad campaignsExplicit consent given via iOS tracking permissionCan be withdrawn in iOS Settings → Privacy & Security → Tracking

5. Processing of Special Categories of Personal Data

Within the scope of our app, the following data is considered "special categories of personal data":

The Movement information/acceptance is recorded with its version and date. The account-level AI-processing setting is recorded separately. The core fasting timer and the water reminder can be used without these features.

Storage location: The Movement profile, readiness records, and session history are stored, linked to the account, in the server database hosted by Supabase (EU/Frankfurt). Account-linked local copies may also exist on the device so that the app can work.

Retention period: Movement records are kept until the account is deleted. Deleting the account deletes these records together with the account. No shorter automatic retention period is applied to Movement records.

Data limits:

- Access is restricted by authorization controls

- Raw pain, body region, joint limitations, doctor restriction, pregnancy or postpartum indicator, raw readiness responses, and rule reason codes are not sent to Google Gemini

- The other weekly health-related summaries in Section 6.2 are sent to Google Gemini only while the AI-processing choice is on

- Not used for advertising purposes

6. Data Processing with Artificial Intelligence (AI)

AI Data Processing Notice: Our AI processors are Google LLC (Gemini API) and Anthropic, PBC (Claude API). Processing takes place in the USA. Meal text and meal photo analysis use Anthropic or Google, with Google as the fallback. Menu scanning, nutrition-label photo extraction, QR-menu PDF/text extraction, activity calorie estimates, weekly insights and barcode web search use Google. Momo Coach recipients are Anthropic, PBC (Claude API) and Google LLC (Gemini API), in the United States. For users who accepted the current in-app consent text, Momo Coach's primary provider is, where available, Anthropic, PBC (Claude API), with Google LLC (Gemini API) as the fallback. When the fallback is used, the same message may also be sent to Google LLC (Gemini API). Momo Coach messages from users who accepted an earlier in-app consent text are processed by Google LLC (Gemini API) until they accept the current text. No account identifiers are added to these requests. Before starting a food-text, food-image, or activity analysis request, the mobile client checks the account's AI-processing setting. The weekly transfer is made on the server side only while the account value is true; a missing, false, or unreadable value blocks a new weekly Gemini request. Optional barcode web lookup sends the scanned or entered product barcode and app language to Google Gemini (Google LLC, United States), through our server, to search for product sources after a definitive database miss. It does not send your health records, name, email, or direct account identifier to Google. The first lookup requires a separate explanation and acceptance of this purpose, as well as enabled AI processing; later database misses may trigger this lookup automatically while that setting remains enabled. The purpose acknowledgement is stored on this device for the signed-in account. Turning AI processing off prevents new lookups. Only Fasting does not save the live grounded answer or search suggestions as a product record or reusable result cache; provider-side handling remains subject to Google’s applicable terms and settings. Under Anthropic's commercial terms, content submitted through its API is not used to train its models by default.

6.1 Data Sent in Food and Activity Analysis

DataPurpose
Food descriptions (text)Calorie and nutrient value estimation
Food photosVisual nutrient analysis
Activity descriptions (text)Burned-calorie estimation
Body weight (kg)Activity calorie calculation

6.2 Data Sent in the Weekly Analysis

To create the weekly text, the following fields are sent to Google Gemini:

6.3 Data Not Sent in the Weekly Analysis

The following are not added to the weekly request:

- Direct user or account ID, name, and email

- Raw meal logs

- Raw readiness or body values and reason codes

- Pain flag, body region, rest reasons, readiness energy value, and qualification data

- Recent insight free text

Identification risk: Although direct identity information is not sent, exact dates, time zone, and language/locale information can contextually help to single out the person.

6.4 Retention and Provider Terms

Only Fasting does not store the weekly Gemini request text as a separate user record. Temporary retention, logging, and model use on Google's side are subject to Google's service settings and the applicable provider terms; this text gives no commitment about a specific period or about model training.

6.5 Automated Operations

Calorie estimation with AI is an automated decision-making mechanism. However:

The Movement feature uses a separate rule-based screening. Depending on the responses, it may not offer a plan, or it may show a message to rest or to seek a professional opinion. These Movement decisions are not produced by Google Gemini.

6.6 Momo Coach (AI Chat)

Momo Coach is an optional chat feature for Premium users aged 18 or older, where available; it requires age confirmation, separate explicit consent, and the AI-processing setting to be on. With each message, the following is sent to our AI providers listed here: the message you write, up to the last three questions and answers of the same chat, a summary of your records (water, meals, calories, fasting, weight trend, meal plan, Apple Health / Health Connect totals if connected, and weekly insight results, for today, the last 7 days, and a 28-day total), your goals, diet-type and allergy selections, the date, time zone, and app language. Your name, email, profile photo, direct user or account ID, and free-text meal names and notes are not sent. The detailed list is in Section 2.4 of the Explicit Consent Text.

Retention and access: Unlike the weekly analysis, Momo Coach conversations are stored. For every request, the message, the answer or the fixed message shown, the record summary sent to the model, the model's raw output, the automated safety decisions, and technical details are kept in an encrypted record. Only authorized persons can access the record, for the Momo Coach purposes in Section 3, and every access is logged. The records are not sold and are not given to third parties to train AI models. The periods are in Section 9.

Deletion and withdrawing consent: You can delete your visible chat history at any time in the app with "Delete chat history"; this does not delete the encrypted Momo Coach record, which remains until the end of its retention period. You can withdraw your Momo Coach consent at any time in the app; after that, no new Momo Coach message is sent to our AI providers listed here.

7. Parties to Whom Personal Data Is Transferred

RecipientPurposeData TransferredLocation
Google LLC (Gemini API) and Anthropic, PBC (Claude API)Meal text and meal photo analysis use Anthropic or Google, with Google as the fallback. Menu scanning, nutrition-label photo extraction, QR-menu PDF/text extraction, activity calorie estimates, weekly insights and barcode web search use Google. Momo Coach recipients are Anthropic, PBC (Claude API) and Google LLC (Gemini API), in the United States. For users who accepted the current in-app consent text, Momo Coach's primary provider is, where available, Anthropic, PBC (Claude API), with Google LLC (Gemini API) as the fallback. When the fallback is used, the same message may also be sent to Google LLC (Gemini API). Momo Coach messages from users who accepted an earlier in-app consent text are processed by Google LLC (Gemini API) until they accept the current text.The data listed one by one in Sections 6.1 and 6.2; for the weekly request, the data in Section 6.3 is excluded; for Momo Coach, the data in Section 6.6; Optional barcode web lookup sends the product barcode and app language; no health records or direct account identifier.USA
RevenueCatSubscription managementAccount-linked user ID and purchase dataUSA
PostHogProduct analytics (can be turned off in the settings)Account-linked user ID, usage events and limited event properties, device type, app version; Movement events may include energy, effort, date, general outcome, and plan information. Raw pain, body region, body values, and reason codes are not sent.EU (Germany)
SentryError monitoring (can be turned off in the settings)Crash reports and error logsUSA
AppleSign in with Apple / SubscriptionEmail (optional), nameUSA
GoogleSign in with GoogleEmail, name, profile photoUSA
SupabaseDatabase hostingAccount and app data, including the Movement profile, readiness, and session recordsEU (Frankfurt, Germany)
Expo Push Service (with APNs/FCM delivery)Sending notificationsExpo push token and notification contentProvider infrastructure
Meta Platforms Ireland Ltd. / Meta Platforms, Inc. (Meta SDK)Measuring and optimizing Only Fasting ad campaigns on iOS, only with tracking permissionDevice advertising identifier (IDFA), install, app-open and session events; device model, OS and app version, language/locale, time zone, screen size, carrier/network information (including IP address), and the SDK's own anonymous app-install ID; only with iOS tracking permissionIreland / USA

8. Transfer of Data Abroad

Important Information: Part of your personal data is transferred abroad (to the USA and EU countries) through our service providers.

8.1 Transfer Services and Controls in the App

LocationServiceControl in the App
USAGoogle LLC (Gemini API) and Anthropic, PBC (Claude API) (AI analysis)The AI-processing setting is checked before mobile food-text, food-image, and activity requests; the weekly request is sent only while the account value is true
USARevenueCat (subscription)Used during subscription transactions
USASentry (error monitoring)On by default; can be turned off under Profile > Privacy & Data > Crash Reporting
USAApple / Google (OAuth)Used when the user chooses the respective sign-in provider
EU (Germany)Supabase (database)Used for the account and for data synchronization across devices
EU (Germany)PostHog (analytics)On by default; can be turned off under Profile > Privacy & Data > Usage Analytics
Provider infrastructureExpo Push Service (with APNs/FCM delivery)Used through the notification settings and the system notification permission
Ireland / USAMeta Platforms Ireland Ltd. / Meta Platforms, Inc. (measuring and optimizing Only Fasting ad campaigns)Transferred abroad only on explicit consent given via iOS tracking permission; permission can be withdrawn in iOS Settings → Privacy & Security → Tracking

8.2 Transfer Limits

9. Data Retention Periods

Data TypeRetention PeriodDeletion Method
Account data (email, name)Until the account is deletedPermanent deletion with an account deletion request
Fasting recordsUntil the account is deletedAutomatic with account deletion
Water intake records2 yearsAutomatic deletion (scheduled job)
Meal logs2 yearsAutomatic deletion (scheduled job)
Health data (weight, BMI)Until the account is deletedWith account deletion or upon a deletion request
Health platform data (supported activity, body, sleep, and resting heart rate)Until the account is deleted; no new data is transferred once synchronization is turned offAutomatic with account deletion; deletion on request
Movement profile, readiness, and session recordsUntil the account is deleted; no shorter automatic retention period is appliedDeleted together with the account when the account is deleted
AI analysis inputsThe weekly Gemini request text is not stored as a separate user record; this text does not commit to a specific period for provider-side retention. For Momo Coach chats, the rows below applyGoogle's and Anthropic's service settings and applicable provider terms apply
Analytics data12 monthsWhen the analytics choice is turned off, sending of new events stops; a deletion request can be submitted for existing records
Audit logsOrdinary audit logs: 2 years; account-erasure operation records: at least 3 yearsAutomatic deletion after the retention period. Account-linked ordinary audit details are removed on account deletion; records of starting and completing erasure do not retain account, network or device identifiers.
Device tokens (notifications)Until sign-out or 90 daysOn sign-out or by automatic cleanup
Subscription recordsIn the app database until the account is deleted; store and subscription-provider records according to their own terms and legal obligationsOn account deletion, the app record is deleted; for the provider record, the respective provider's process applies
Device-level free-use record (the app's device ID and which one-time free allowances, such as free AI analyses or scans, have been used on that device)Kept after account deletion to prevent repeated use of one-time free allowancesNot deleted with account deletion
Momo Coach visible chat history30 daysAutomatic deletion; earlier with the in-app "Delete chat history" option; together with account deletion
Encrypted Momo Coach record (message, answer, record summary sent to the model, safety decisions, technical details)2 years; after account deletion, until the end of the period under a pseudonymous code instead of the account ID; if there is a specific legal claim or dispute, until that matter is closedAutomatic deletion (scheduled job); not deleted by deleting the visible history or by account deletion
Momo Coach usage-limit records (coded digests of account and store-purchase identifiers, request receipts)32 daysAutomatic deletion (scheduled job)

Data already received by Meta is processed under Meta's own policy and is not deleted by us; you can exercise your rights with Meta and withdraw tracking permission in iOS Settings → Privacy & Security → Tracking.

10. Your Rights as a Data Subject

Pursuant to Article 11 of Law No. 6698, you have the following rights:

RightDescriptionHow to Exercise
Right to be informedLearning whether your personal data is being processedprivacy@onlyfasting.com
Requesting information if processedObtaining information about the processed dataprivacy@onlyfasting.com
Learning the purpose of processingLearning the purpose for which the data is processed and whether it is used in line with that purposeThis disclosure notice + email
Transfer informationLearning whether the data has been transferred within the country or abroadSections 7-8 of this text + email
RectificationRequesting the correction of incomplete or inaccurate dataIn the app: Profile > tap your name ("Tap to edit")
ErasureRequesting deletion under KVKK Article 7In the app: Profile > Privacy & Data > Delete Account Permanently or the web form
Notification of rectification/erasureRequesting that the rectification or erasure be notified to the third parties to whom the data was transferredprivacy@onlyfasting.com
Objection to an analysis resultObjecting to a result against you that arises from the analysis of the processed data exclusively through automated systemsprivacy@onlyfasting.com (including AI analysis results)
Compensation for damageClaiming compensation if you suffer damage because of unlawful processingprivacy@onlyfasting.com
Data portabilityDownloading your data in a structured format (JSON)In the app: Profile > About > Export Data

Response Time: Your requests will be answered within 30 days at the latest.

How to Apply: You can send an email to privacy@onlyfasting.com together with information that verifies your identity.

Right to Complain: If your requests are rejected or you do not receive a response, you have the right to apply to the Personal Data Protection Board.

11. Children's Data

Only Fasting is not an app intended for children. You must be at least 13 years old to create an account and use the app. If you are between 13 and the age of digital consent in your country, you may use the app only with the consent of your parent or legal guardian.

We do not knowingly collect personal data from children under 13. If we learn that such data has been collected, we delete it without delay. If you believe a child has given us personal data, notify us at privacy@onlyfasting.com.

Health note: fasting and calorie restriction can be harmful to children and adolescents who are still growing.

12. Data Breach Notification

If your personal data is obtained by others through unlawful means, in accordance with KVKK Article 12/5 and the Personal Data Protection Board's decision on data breach notification:

13. Contact

Data Controller: Mustafa Baykal

Privacy Questions: privacy@onlyfasting.com

General Support: support@onlyfasting.com

Website: onlyfasting.com

This disclosure notice was last updated on October 18, 2026. You will be informed by an in-app notification if it is updated.