A timer counts hours. The SPARK Chart shows what those hours are working toward — and when it's time to eat, guided refeeding tells you how to start.
Most fasting apps count hours. SparkFast shows you what those hours might mean — estimated biological milestones that give you a reason to keep going.
THE SPARK CHART
Your fasting hours aren't just numbers. The SPARK Chart visualizes five estimated biological processes — from early insulin changes to deep cellular recycling — based on published research. It transforms a blank timer into a roadmap of what you're working toward.
GUIDED REFEEDING
Breaking a prolonged fast matters as much as the fast itself. SparkFast provides step-by-step refeeding protocols tailored to your fast duration and dietary preference. No more Googling "how to break a 72-hour fast" mid-fast.
AI-POWERED PERSONALIZATION
Tell SparkFast about your goals, experience, dietary preferences, and schedule. Our AI creates a custom fasting plan built around your life — not a one-size-fits-all template.
CHALLENGES THAT BUILD HABITS
Built-in challenges — from a beginner-friendly 5-day start to a 72-hour deep fast — give you structure and milestones to work toward. Track progress, earn achievements, and build consistency.
BIOMARKER TRACKING (OPTIONAL)
For users who track glucose, ketones, GKI, or Dr. Boz Ratio: type readings in, or import them from your Keto-Mojo meter. See how your metabolic data trends alongside your fasting practice. Most users start without this — it's there when you're ready.
ALSO INCLUDES
- Intermittent and prolonged fasting schedules (16:8, 18:6, OMAD, 36h, 48h, 72h+)
- Apple Health and Health Connect sync for weight, sleep and steps
- Step history by week, month and year, with your own entries for the days you walked without your phone
- Motivational notifications at key fasting milestones
- Eating window and hydration tracking
- Stool tracking for gut health awareness
- Custom trackers for anything you want to monitor
BUILT FROM EXPERIENCE
SparkFast was born when co-founder Veronica — who changed her own health through fasting — realized she kept printing charts of estimated biological milestones and sticking them on her kitchen wall to stay motivated during 72-hour fasts. That piece of paper became this app.
IMPORTANT
The SPARK Chart shows estimated timelines based on published fasting research. Actual metabolic responses vary between individuals based on diet history, metabolic health, and other factors. SparkFast is a motivational and educational tool, not a medical device.
YOUR PRIVACY
SparkFast does not sell personal data. All information is stored securely and encrypted.
SUBSCRIPTION
SparkFast requires a subscription for full access. Options include monthly and yearly plans, both with a free trial. Payment is charged to your Apple ID at purchase and renews automatically unless cancelled at least 24 hours before the end of the current period. Manage subscriptions in App Store settings.
Terms of Service: https://www.sparkfast.app/terms-of-service
Privacy Policy: https://www.sparkfast.app/privacy-policy
Ratings & Reviews
This app hasn’t received enough ratings or reviews to display an overview.
• Clearer timing: the wait now sits between two steps, with a live countdown, and one reminder tells you when the next step is due — no more reminders for steps you skipped.
• You can finish a refeed at any time, and change protocol in the middle of one.
• Editing the start time of a prolonged fast no longer closes the card and sends you back to the list.
• The celebration screen says the right thing when you are not fasting for the first time.
• The Keto-Mojo connection shows its state quietly and correctly.
Version 1.0.53
The developer, SparkFast Technologies LLC, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Linked to You
The following data may be collected and linked to your identity:
Health & Fitness
Contact Info
Identifiers
Usage Data
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
Diagnostics
Privacy practices may vary, for example, based on the features you use or your age. Learn More
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
