SparkFast is an intermittent fasting and prolonged fasting tracker app that helps you monitor your fasting progress, track metabolic health markers like glucose and ketones, follow guided refeed protocols, and achieve your health goals through structured challenges and achievements.
The SPARK chart is a theoretical progress tracker that visualizes the cellular benefits your body experiences during a fast. The name SPARK is an acronym representing five key metabolic stages:
The SPARK chart shows your real-time progress through these phases as your fast progresses, helping you understand the science-backed benefits happening inside your body at each stage.
To start a fast, open the app and tap the "Start Fast" button on the home screen. Choose between intermittent fasting (12:12, 14:10, 16:8, 18:6, 20:4, OMAD) or prolonged fasting (36h, 48h, 72h, 96h), or create a custom fast with your preferred duration.
SparkFast offers a 7-day free trial so you can explore all features before committing. After the trial, you can continue with a monthly or yearly subscription plan. You can also apply a promo code during signup for special access.
SparkFast supports all popular intermittent fasting schedules including 12:12, 16:8, 18:6, 20:4, and 23:1 (OMAD). You can also create a custom intermittent fasting schedule with your own eating window times.
Prolonged fasting is any fast lasting longer than 24 hours. SparkFast supports prolonged fasts including The Autophagy Spark (36h), Peak Repair (48h), The Regenerator (72h), and Sustained Renewal (96h). You can also set a custom duration for fasts of any length.
The SPARK phases represent the cellular repair stages your body goes through during a fast. SparkFast tracks your real-time progress through these phases, showing when your body enters fat burning, ketosis, autophagy, and deep cellular renewal.
A refeed protocol is a structured eating plan that guides you on what to eat and when after completing a prolonged fast. SparkFast provides default refeed protocols for 36h, 48h, 72h, and 96h fasts with step-by-step instructions to safely reintroduce food and avoid digestive discomfort.
Yes, you can create custom refeed templates in SparkFast. Tap the "Customize This Protocol" button to copy any default protocol and modify the food items, timing, and sequence to match your dietary preferences.
SparkFast lets you track blood glucose and ketone readings manually or automatically through integrations with Apple Health, Google Fit, and Keto-Mojo. Navigate to the Health Tracking section to log readings or view your metabolic trends.
GKI (Glucose Ketone Index) is a ratio that measures your metabolic health by dividing your glucose level by your ketone level. SparkFast automatically calculates your GKI when you have paired glucose and ketone readings taken within a 15-minute window, and displays your metabolic zone.
The Dr. Boz Ratio is a metabolic health metric created by https://bozmd.com/ — a board-certified internal medicine physician, bestselling author of Anyway You Can and Keto Continuum, and a leading expert in ketogenic nutrition and metabolic health. Dr. Bosworth developed this simplified ratio to help patients monitor their metabolic state without complex math.
The formula is: Blood Glucose (mg/dL) ÷ Blood Ketones (mmol/L). Unlike the GKI which requires converting glucose units first, Dr. Bosworth intentionally skipped this conversion step to make the calculation more user-friendly and less prone to error.
SparkFast automatically calculates your Dr. Boz Ratio when you have paired glucose and ketone readings, and displays your metabolic zone:
You can choose between GKI or Dr. Boz Ratio as your preferred metabolic display in Settings.
You can track your weight by entering readings manually or syncing automatically from Apple Health or Google Fit. SparkFast shows your weight history chart, BMI calculation, and progress toward your goal weight.
Yes, SparkFast includes a hydration tracker to log your daily water intake. You can customize your glass size, set a daily water goal, and enable hydration reminders at your preferred frequency during fasting.
Yes, SparkFast tracks sleep duration and stages (light, deep, REM) through Apple Health or Google Fit integration. The app shows how your sleep patterns correlate with your fasting performance.
Yes, SparkFast integrates with Apple Health on iOS to sync weight, blood glucose readings, and sleep data automatically. Connect Apple Health in Settings > Health Integrations to enable background syncing.
Yes, SparkFast integrates with Google Fit via Health Connect on Android to sync weight, blood glucose, and sleep data. If Health Connect is not installed, the app will prompt you to install it from the Play Store.
To connect your Keto-Mojo meter, go to Settings > Health Integrations > Keto-Mojo. Select your region (US, EU, or Canada), sign in with your MyMojoHealth account, and SparkFast will automatically sync your glucose and ketone readings.
SparkFast sends fasting milestone notifications (at 12h, 18h, 24h, 36h, 48h, 72h), hydration reminders, electrolyte reminders, eating window alerts, refeed step reminders, challenge milestone updates, and motivational messages.
SparkFast sends three eating window notifications: one hour before your eating window opens, when your eating window begins, and one hour before your eating window closes. These help you stay on schedule with your intermittent fasting plan.
Yes, you can set quiet hours in Settings > Notifications to prevent SparkFast from sending notifications during sleep. Set your preferred start and end times (e.g., 10 PM to 7 AM) and the app will respect your quiet period.
Go to Settings > Notifications to enable hydration reminders. You can set the reminder frequency, choose a time window for when reminders are active, and configure electrolyte reminders separately.
Fasting challenges are structured programs that help you build consistent fasting habits. SparkFast offers 25+ challenges across beginner, intermediate, and advanced levels, including day-based consistency challenges and single prolonged fast challenges.
SparkFast awards achievement badges when you reach fasting milestones. Badges range from Bronze to Diamond rarity and include achievements like First Steps (first 24h fast), Week Warrior (7-day streak), and Thousand Hour Hero (1000 total fasting hours).
SparkFast supports customizable units including pounds or kilograms for weight, ounces or milliliters for hydration, and mg/dL or mmol/L for glucose and ketone readings. Change your preferences in Settings.
SparkFast supports sign-in with email/password, Google and Apple. You can create an account or sign in from the welcome screen.
To delete your account, go to Settings > Profile and follow the account deletion process. This will permanently remove your data.
If your fasting timer is not displaying, ensure you have an active fast running. Check the home screen for the "Start Fast" button. If the issue persists, try closing and reopening the app.
If your glucose, ketone, or weight readings are not syncing, verify that you have granted SparkFast permission to access Apple Health or Google Fit and Keto-Mojo in your device settings. Also check that background sync is enabled in the app settings.
If you are not receiving SparkFast notifications, check that push notifications are enabled in both the app settings and your device settings. Also verify that quiet hours are not active during the time you expect notifications.
If you want to see the refeed protocol tutorial again, you can reset it from the Settings page. The guided tour will show you how to select protocols, manage templates, and customize your refeed plan.
SparkFast provides educational content about fasting but is not a substitute for professional medical advice. Always consult with a healthcare provider before starting a fasting regimen, especially if you have underlying health conditions.
SparkFast uses Firebase security with encrypted data storage, App Check for bot protection, and follows GDPR compliance practices. Your email is never logged to crash reporting services, and all health data stays secure in your private account.
We love hearing from our users! If you have ideas for new features or improvements, please email us at support@sparkfast.app with "Feature Request" in the subject line.
Email: support@sparkfast.app
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