Support

Open the Timer tab and tap Start Fast. ZenithFast uses the fasting plan set in your Plans tab. You can change your plan any time from Plans.

Go to Plans and select a new plan from the fasting plan list. The change takes effect from your next fast.

An account is required to sync your data across devices and keep your history safe. Sign-up is free and takes only an email — no password needed.

ZenithFast tracks five phases based on the hours elapsed since your last meal:

• Fed State (0–4 hrs) — digestion and nutrient absorption.
• Early Fasting (4–12 hrs) — insulin drops, glycogen begins depleting.
• Fat Burning (12–18 hrs) — your body switches to stored fat for fuel.
• Deep Fasting (18–24 hrs) — autophagy activates; cellular repair begins.
• Ketosis (24+ hrs) — brain runs on ketones; peak mental clarity.

These are general guidelines, not medical thresholds. Individual responses vary.

ZenithFast can read and write weight data to Apple Health on iOS and Health Connect on Android. Enable this in Settings → Profile.

Open the Water tab and tap one of the quick-add buttons, or enter a custom amount. Your daily goal is shown at the top and adjustable from Settings → Profile.

ZenithFast supports both metric (ml) and imperial (fl oz). Change your preference under Settings → Units.

Subscriptions are managed by the App Store or Google Play. Cancel via your device's subscription settings — ZenithFast cannot process refunds directly.

Go to Settings → Profile → Delete Account. This permanently removes all your data within 30 days. This action cannot be undone.

• Check your spam or junk folder.
• Make sure you entered your email address correctly.
• Wait up to 60 seconds before requesting a new code.
• If issues persist, contact us at the address below.