What is a fasting zone?
Fasting Zones are a way to understand what's happening inside your body during a fast. While the basic features of Fasting Zones are available to all users, advanced tracking features and expanded content require a Zero Plus subscription.
Until now, fasting zones were standardized timeframes that showed the current fasting state of your body. These standardized timeframes were:
- Anabolic: 0-4h of a fast (4 hours in length)
- Catabolic: 4-16h of a fast (12 hours in length)
- Fat Burning: 16-24h of a fast (8 hours in length)
- Ketosis: 24-72h of a fast (48 hours in length)
- Deep Ketosis: 72h+
Based on your unique body profile and lifestyle, you may enter these zones earlier (more efficient) or later (less efficient) than these times. Accordingly, our new Personalized Fasting Zones feature will allow you to more accurately track your personal fasting experience.
Introducing: Personalized Fasting Zones
Using the information you provide, we give you real-time insight into how you are progressing through your fast by displaying three statistics to keep an eye on:
- Standard length in a current zone. This represents the amount of time the average person spends in each zone and does not take into account your body composition, diet, or activity.
- Your length in a zone. A personalized metric that tells you how much time you will spend in a given zone within your current fast. This metric will change as you log activity or ketone levels.
- More/Less Efficient than standard Fasting Zones.
- Being more efficient indicates an acceleration through the Fasting Zones, helping you to unlock the benefits of deeper zones (like Ketosis) earlier in your fast.
- Being less efficient means you will notice it takes a bit longer to progress through fasting zones. This isn't necessarily good or bad—it is simply a result of your default fasting zone inputs (see FAQs below for more information).
- If you'd like to raise your fasting zone efficiency, consider adding some exercise during your fast or exploring meals lower in carbohydrates.
- To view fasting zone details at any time during a fast, tap the Today tab then tap either on the fasting zone label below the digital countdown timer, or the current zone on the progress ring (this is at the end of the circle) as shown below.
- When you tap into the detailed view on the timer, you'll be taken to the current fasting zone that you are in, with an indicator bar showing your progress into that zone. You can see your personalized fasting zone times by tapping on that particular zone (anabolic, catabolic, fat burning, etc.).
Your fasting timeline displays the activities that influence your Personalized Fasting Zones. It displays immediately beneath the graph, and in a vertical scroll where you can read more information. The three types of activities that display in your timeline are:
- Exercise: Any manually logged or automatically tracked (see Connecting to Apple Health and Google Fit or Connecting to Fitbit, Oura, and Biosense) exercise will display in your timeline. If you do not exercise, your fast will still be personalized based on whether you have a Sedentary or Active lifestyle.
- Pre-Fast Meal: Logging meals during your eating window (the time between one fast's end and the next fast's start) determines your starting energy store. We use meals logged in the hour before you start fasting. If no meal was logged we use your dietary preference from the initial setup assessment.
- Ketones: Any manually logged or automatically tracked (through our Biosense integration) ketones will display in your fasting timeline and affect your zones. Logging elevated ketone levels early in your fast can accelerate your transition through zones rapidly.
- Note: Currently, ketone logging within Zero is limited to same-day entries
How do I change my initial personalized fasting zone inputs?
The first time you used the personalized fasting zone feature, you entered information about your lifestyle, diet, and body profile. You can change these values at any time by following these steps:
- During a fast tap the Today tab
- Tap the fasting zone icon of the current zone inside the timer ring or the icon on the timer ring
- Scroll down and tap 'Edit Defaults' which is just below your inputs
How do I ensure my personalized fasting zone timeframes are accurate?
- Be sure to log your activities throughout the day
- Periodically review and update your lifestyle, diet, and body profile inputs
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