More than a fasting timer. See the estimated milestones behind every fasting hour — autophagy, ketones, cell renewal — and break your fast safely with guided refeeding.
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: log readings manually or sync from Keto-Mojo and Apple Health. 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 integration for weight, sleep, steps, and heart rate
- 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 went from a BMI of 32 to a normal BMI 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.
This update keeps SparkFast running smoothly:
• Updated security and performance libraries
• Clearer messaging when your subscription expires, so you always know your account status
• Improved error handling and general stability fixes
Version 1.0.48(71)
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
Information
Seller
Sparkfast Technologies LLC
Size
99 MB
Category
Health & Fitness
Compatibility
Requires iOS 14.0 or later.
iPhone Requires iOS 14.0 or later.
iPad Requires iPadOS 14.0 or later.
iPod touch Requires iOS 14.0 or later.
Mac Requires macOS 11.0 or later and a Mac with Apple M1 chip or later.
