Intermittent fasting (IF) is currently one of the most thoroughly researched nutritional interventions. But note: fasting isn't just about "losing weight". Its most powerful effects happen at the cellular level — autophagy, mitochondrial repair, regulation of inflammatory pathways and activation of genes linked to longevity.
How to read the numbers: Fact = a finding from research or biology · Term = a key term or marker worth knowing · How-to = a practical step or time frame
The most common IF
With 16:8 you eat within an 8-hour window and fast for 16 hours – the simplest and most common form of intermittent fasting. Research shows benefits mainly when it helps reduce overall intake; a good start is simply skipping late-evening meals.
Peak cellular cleanup
Autophagy is the process by which cells recycle damaged components; in animals it rises markedly during longer fasts, but its exact timing in humans has not yet been reliably measured. Do not attempt multi-day fasts without talking to your doctor.
The switch between growth and cleanup
mTOR is a signalling pathway that promotes growth and muscle building when nutrients and protein are plentiful, while its suppression during fasting favours cellular clean-up. The aim is not to suppress mTOR permanently but to alternate periods of eating and pauses.
What happens in your body during a fast
First 4 hours: insulin falls and liver glycogen is used up. 8–12 hours: the body switches to burning fat. 14–16 hours: autophagy kicks in — cells start their "housekeeping". 24+ hours: stem cell regeneration and a dramatic drop in inflammatory markers.
16:8 (a 16-hour fast, an 8-hour eating window) is the most widely used protocol. Women are advised to start with 14:10. Longer fasts (24–72 hours) have more pronounced regenerative effects, but they require preparation and monitoring.
Who should not fast
Pregnant and breastfeeding women. People with eating disorders. Diabetics on insulin without medical supervision. People with a very low BMI. And anyone whose doctor advises against it after assessing their health.
