Nutrition
Intermittent Fasting Window Planner
Plan your eating and fasting windows for 16:8, 18:6, 20:4, 14:10 or OMAD, or your two low-calorie days for 5:2, with a meal schedule.
Result
Meal schedule
- Meal 112:00 PM
- Meal 24:00 PM
- Meal 37:45 PM
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
- Pick a protocol, which sets the eating window, and your first meal time; add your daily calories to see them split across the meals. Common protocols: 16:8 (16h fast, 8h eat), 18:6, 20:4; for 5:2, pick your two low-calorie days instead. 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 non-consecutive low-calorie days each week and eat normally on the other five. The planner marks those days on a week view and sets their target at about a quarter of a normal day: a quarter of your daily calories if you enter them, otherwise the usual 500 to 600 kcal.
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.
The formula, worked through
- Formula Intermittent Fasting Window Formula
Intermittent fasting window planner: 16:8 base, ±2h around training. Stockman 2018 meta — fat loss equivalent to caloric restriction, no metabolic advantage.
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Background on the Intermittent Fasting Window Planner
- Guide Intermittent Fasting for Beginners: How to Start
A practical beginner's guide to intermittent fasting: which protocol to start with, how to handle hunger, what the research actually shows, and who should.
- Comparison 16:8 vs OMAD: Which Intermittent Fasting Protocol Is Better?
Compare 16:8 and OMAD fasting for fat loss, muscle retention, adherence, and health. Evidence-based analysis of when each protocol makes sense.
- Examples Intermittent Fasting Examples
Explore practical intermittent fasting examples for diverse lifestyles, from busy professionals to endurance athletes. Understand how flexible fasting.
- Checklist Intermittent Fasting Start Checklist
Start an intermittent fasting plan with this actionable checklist. Prepare your body, plan your windows, and set yourself up for success with clear steps.
- Guide How to Start Intermittent Fasting Safely
How to start Intermittent fasting Safely: begin intermittent fasting safely with expert guidance.
- Comparison Intermittent Fasting vs Regular Meals
Intermittent fasting vs regular meals: metabolic effects, hunger pattern differences, adherence rates, and social fit compared with peer-reviewed data.
Articles
- 7 min read How to Run a Mini Cut
Run a mini-cut: the 4-6 week deficit window, weekly weight-loss target, training-volume scaling, and re-feed criteria to avoid muscle loss.
- 6 min read 16:8 Intermittent Fasting Starting at Noon: A Realistic Schedule
Intermittent 16:8 with a noon first meal: the eating window, training-window timing, and where protein distribution math creates a real problem.
By goal
Use it from code
The same calculation as a JavaScript module you can import. It runs where you import it, with no request, key or rate limit.
import { compute } from "https://aifithub.io/engines/intermittent-fasting-window-planner.js";Input and output contract, TypeScript types and the guide for agents.