Fasting overview
  • 12 Feb 2024
  • 4 Minutes to read
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Fasting overview

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  • PDF

Article summary

Intermittent fasting (IF) is a practice often used in combination with a low-carb or ketogenic diet. This article describes how Premium members can set and track fasting goals, log foods and supplements during a fast, and view and analyze fasting trends.

Carb Manager includes several standard fasting programs, such as 12:12, 16:8, the Warrior Diet, or OMAD, or you can create a custom program. Each standard program runs seven days a week until you stop it. With a custom program, you can set custom fasting and eating windows for the full week, weekdays only, weekends only, or for specific days of the week.

Tip: To learn more about intermittent fasting, go to Community iconConnect, select the Articles tab, and select the Fasting button below the search field.

Watch: How to Set Up Intermittent Fasting in Carb Manager

1. Start a fasting program, set a goal

When you start a standard or custom fasting program, Carb Manager automatically sets a goal based on your fasting window to help you track your progress over time.

  • Go to Settings icon Settings > Intermittent Fasting and select one of several standard programs or create a custom program.

For more information, see the following articles:

Tip: After you start a fast, the Intermittent Fasting section of the daily log shows when your fasting and eating windows begin and a timer that shows how much time has passed since your last meal or fast. For more information, see View fasting and eating windows.
Tip: You can stop a fasting program at any time.

2. Log food within your eating window to maintain your fast

Note: If you try to log food or supplements during a fasting window (outside of the eating window), Carb Manager will ask you if you want to break your fast or keep fasting. If you choose to log the item and keep fasting — for example, if you are logging supplements or coffee before your eating window — Carb Manager will not break your fast and stop the fasting timer. If you accidentally break your fast by logging a food at the wrong time, you can edit the timestamp of the food. See the tip below.
Tip: To change the food's timestamp to a time within your eating window, select Cancel to return to the food's detail screen, select Show Advanced, and select a different Date or Time. Then, select Add to log the food.

3. Flexible fasting -- Adjusting eating and fasting windows and timestamps

If you intend to eat outside of your current eating window and don’t want to break your fast, you must be mindful of two things.

  • Adjust the eating window to match the change. For example, if your 8-hour eating window begins at 11:00 AM but you decide to start eating at 10:00 AM, adjust the start of the eating window using the daily log Intermittent Fasting timer. You can also lengthen or shorten your eating window to shorten or lengthen your fast.
  • Adjust the timestamp before you log a food that you consumed at a time other than the current time of day. Open a food's detail screen, and select Show Advanced to see the food's time setting. Then select the clock and change the hours, minutes, or AM/PM to the desired time. If you forget to change the time before logging, you can also change the time after logging food. Regardless of how you change your timestamp, Carb Manager will adjust your eating and fasting windows accordingly. Though eating and fasting windows are in 30-minute increments, the summary info will record down to one-minute increments based on food timestamps.
Tip: To set a 0-hour eating window, select Edit in the daily log Intermittent Fasting timer and choose the All-Day Fast option. If you choose not to fast today, select Free Day in the Intermittent Fasting timer editing window. 

4. Mark each day as complete (optional)

  • When you finish logging food and supplements each day, go to the Daily Log icon Daily Log and select I’m Done Logging Today.
Important: If you skip logging meals for an entire day because you were fasting during that period, select I’m Done Logging Today. If you don't, Carb Manager assumes that you forgot to log items and will not include skipped days in your nutrition summaries or your fasting windows.

5. View and analyze your fasting over time

Complete the following steps to view progress charts of your fasting hours and eating hours over periods of time.

  1. Go to Goals icon  Goals in the main menu.
  2. In the Progress tab, select Change to view categories of all measurements that are available.
  3. In the All Measurements screen, select Lifestyle.
  4. In the Lifestyle screen, select Eating Hours Per Day or Fasting Hours Per Day.
    Note: Fasting time is calculated as the time before you started eating and the time after you finished eating, starting at 12:00 am and ending at 11:59 pm each day. Basically, fasting shows the opposite of your eating window. For example, if you are on a 16:8 fasting schedule, you'll want to keep your fasting time close to 16 hours.
    Since a fasting period typically spans two dates, this can cause confusion when reading the fasting or eating hours on the charts. Today’s date will not show your total eating and fasting window hours until tomorrow. Instead, you will see a zero.
    Tip: Select the Favorite icon heart next to a measurement to add the item to your list of favorite measurements.
    Tip: For more information about tracking progress over time, see View progress and gain insights toward goals.