UNDERSTAND THE METHOD
How to use this calculator
Choose a daily eating window or the separate 5:2 weekly pattern. Daily times use a 24-hour clock. Day +1 means the following day. A schedule is not a calorie target.
What the result can tell you
This planner is for adults. Fasting is not appropriate for everyone, including children, pregnancy, breastfeeding, and people with an eating disorder. Discuss fasting with your clinician if you have diabetes or use medicines that affect glucose. Clock time cannot confirm ketosis or autophagy.
Common questions
What is the difference between the daily and 5:2 options?
The daily option uses a repeating eating window. The separate 5:2 option uses a weekly pattern. Times use a 24-hour clock, and day +1 means the following day.
Is this fasting schedule suitable for everyone?
No. This adult planner is not appropriate for everyone, including children, pregnancy, breastfeeding, and people with an eating disorder. If you have diabetes or use glucose-affecting medicines, discuss it with your clinician.
Sources & limitations
Sources checked September 12, 2026. These notes identify methods and assumptions. They have not received an independent clinical review.
- Review of intermittent fasting and its limits.pubmed.ncbi.nlm.nih.gov
- Study of intermittent energy restriction.pubmed.ncbi.nlm.nih.gov