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What happens in your body while you fast? Slide through the hours

Stop eating and your body doesn't flip a switch: it hands over fuel duty step by step, from your last meal to stored sugar in the liver, then to more fat and ketones.

Slide through the first 24 hours to see what's roughly happening and why exact "fat-burning hours" are too neat to trust. Not medical advice: ask a doctor first if you have a condition or take medication.

Slider showing a 16 hour fast on a 24 hour bar, from last meal to fat and ketones

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