Fasting window

Hours are 0–23. Fast is first meal minus last meal, plus 24 if that crosses midnight. Eating window is 24 minus the fast. Not medical advice.

Last meal (hour 0–23)

First meal (hour 0–23)

Fast

16 h

Eating window

8 h

16:8 is last meal at 20 and first at 12. Coffee with milk is still a meal if you are being strict.

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An educational estimate. Not medical, tax or credit advice.

Basal metabolic rate from Mifflin–St Jeor, then a TDEE estimate from activity.

A wake time or bedtime from 90-minute cycles plus the minutes you need to fall asleep.

How much of a dose is still in you after a number of hours.

Hours short of the sleep you wanted, over a run of nights.

Body mass index from weight and height, using the WHO bands for adults.

The US Navy circumference method. A tape-measure estimate, not a DEXA scan.