Glossary

Intermittent Fasting

Updated February 28, 2026

Intermittent fasting is a timing framework for energy intake, not a stand-alone recovery or fat-loss shortcut.

Protocol styles by routine

ProtocolTypical window rhythmFit profile
12:1212 hours fast, 12 hours feedShift workers and first-time users
14:1014 hours fast, 10 hours feedBalanced social and work load
16:816 hours fast, 8 hours feedGood for steady routines when hunger is stable
18:618 hours fast, 6 hours feedBest for high adherence confidence and low training volume

Satiety and adaptation patterns

PhaseExpected patternWhat to track
Days 1 to 7Hunger front-loads around window opensnote meal timing and sleep onset
Weeks 2 to 4Meal size becomes more predictablecompare subjective satiety with protein and fiber levels
Weeks 5 to 8Window control becomes routine, not event drivenreview weekly trend from food diary

Override rules

ContextOverride move
Travel and delayed sleepUse a short, stable window instead of a hard target window for 48 hours
High-stress social weekReplace strict fasting with two fixed anchor meals and hydration support
Recovery-sensitive trainingKeep protein and carbohydrate windows around training before strict fasting targets
Repeated morning headaches or low moodPause fasting for 2 to 3 days and reassess with blood sugar control

When to stop and reset

Use nutrient timing, meal planning, and mindful eating patterns to keep adherence up. If fasting windows reduce training quality, restore a wider window for 5 to 7 days before restarting at a lower duration.

Related

Nutrient Timing

Nutrient Timing schedules meals around activity to support performance and recovery.

Calorie Targets

Calorie Targets convert maintenance logic into objective-specific intake targets.

Mindful Eating

Mindful Eating means paying attention to hunger, appetite, and satisfaction signals.