NUTRITION
Intermittent Fasting Window Planner
Plan protocol-based eating and fasting windows with a 24-hour timeline and 5:2 day picker.
Result
24-hour fasting schedule
Eating and fasting blocks mapped onto a single day so the protocol is easy to follow.
Protocol tip
Start with 16:8 if you are new to fasting. Keep meal timing consistent for 1-2 weeks before tightening the window.
How to use it
- Enter your preferred eating window length and first meal time. Common protocols: 16:8 (16h fast, 8h eat), 18:6, 20:4. Longer fasting windows improve compliance for some people but do not inherently improve fat loss at equivalent calories.
- IF does not accelerate fat loss beyond equivalent calorie restriction without time restriction. It works because some people find it easier to skip breakfast than to reduce portion sizes — compliance is the primary mechanism.
- Hunger adapts to your eating schedule within 7–14 days. Significant hunger in the first week is normal and largely resolves as ghrelin rhythm adapts to the new meal timing.
- Protein target must be hit within the eating window regardless of IF protocol. Compressing all meals into 6–8 hours makes it harder to distribute protein for optimal muscle protein synthesis — track protein specifically during IF.
- Coffee, tea, and water do not break a metabolic fast and meaningfully reduce hunger during the fasting window. Cream or milk above 20 calories will partially break a strict fast.
Questions people usually ask
Which fasting protocols are supported?
This planner supports 14:10, 16:8, 18:6, 20:4, OMAD (23:1), and 5:2 scheduling.
How are eating and fasting windows calculated?
Your first meal time sets the start of the eating window. The selected protocol determines eating and fasting durations across a 24-hour cycle.
How does the 5:2 option work here?
For 5:2, you pick two low-calorie fasting days each week. The planner highlights those days and shows a reference 24-hour fasting-day timeline.
Is this tool free and private to use?
Yes. AI Fit Hub tools are free, no-signup browser tools. Inputs stay in your browser unless you choose to share a URL.
Do these tools replace medical guidance?
No. These outputs are general fitness estimates — not medical advice.
Formula
See the math
The underlying formula with variables defined, derivation shown, and a worked example with units.
Related Resources
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