Fasting · Tool 1 of 5
Fasting Window Planner
Most fasting calculators tell you one thing: when your eating window opens. That is the easy part. The hard part is what happens when your only free time to train is 7 a.m. and your window does not open until noon.
Tell me about your day
The three arrangements that work
1. Train inside the window
The simplest option and the one to default to if you are new. You eat, you train, you eat again. It removes the main complaint people have about fasted training, which is that hard sessions feel harder than the effort justifies.
2. Train just before the window opens
This is the arrangement most morning trainers land on. You finish the session and the fast ends within the hour. The catch is that it forces dinner earlier — to run a 16-hour fast that ends at 9 a.m. you have to stop eating at 5 p.m. the day before.
3. Train deep into the fast, and accept the trade
Low-intensity work is generally fine here. Heavy resistance work and hard intervals are where the cost appears, and it appears as session quality rather than as anything dramatic.
What this planner does not decide
It does not set your calories or your protein. Fasting is a schedule, not a diet — it changes when you eat, and that only produces fat loss if it also changes how much you eat over the week.
Questions I get asked
Does black coffee break the fast?
For the purposes of fat loss, no. Plain water, black coffee and unsweetened tea contain effectively no energy. What matters is calories.
Should I train fasted to burn more fat?
Training fasted shifts which fuel you use during the session, but total fat loss over weeks is driven by total energy balance. Choose fasted or fed based on which one lets you train harder and show up more often.
Is a longer fast better?
Longer protocols produce faster short-term change and lower adherence. Pick the longest fast you can hold for three months, not the longest you can hold for three days.
Can women use the same windows as men?
Many can, but the common advice is to start at 14:10 or 16:8 rather than jumping to 18:6 or OMAD, and to shorten the fast if menstrual changes, persistent fatigue or sleep disruption appear.
Read next
- How to Pick a Fasting Window That Fits Your Training Your fasting window and your training slot have to share the same day. Here is how to arrange them so neither one wrecks the other.
- Should You Train Fasted? What Actually Changes Fasted training changes which fuel you burn during the session. Whether it changes your results over weeks is a different question entirely.
- How to Break a Fast Without Undoing the Day The meal that ends your fast sets up everything that follows it. Here is how to build it so the rest of the window stays under control.