When you skip breakfast, lunch, and maybe even dinner, your body first turns to glycogen – stored glucose in your liver and muscles – as its primary energy source. For the first 6–12 hours, you’re simply running on these reserves, much like clearing out the fridge before restocking.

The Big Switch: Entering Ketosis

Once glycogen levels dip (around the 12-hour mark), your body pivots to burning fat instead. This state, called ketosis, transforms fat stores into ketones, which fuel your cells. Suddenly, stored fat becomes active energy – a complete metabolic flip.

Autophagy: Your Body’s Internal Cleanup Crew

Alongside fat burning, your body initiates autophagy – a process of recycling old, damaged, or dysfunctional cells. Think of it as cellular spring cleaning, where your system clears out debris and repairs itself, boosting overall health and resilience.

Hormonal Reset: Insulin, Glucagon, and Growth Hormone

Fasting also triggers powerful hormonal changes:

• Insulin levels drop, improving insulin sensitivity and blood sugar control.
• Glucagon steps in to help release stored glucose when necessary.
• Growth hormone rises, protecting muscle mass while encouraging fat burning.

Together, these shifts make your metabolism more efficient and protective.

Health Benefits Beyond the Fast

These metabolic changes may lead to:

• Improved insulin sensitivity and blood sugar regulation
• Reduced inflammation and joint discomfort
• Sharper focus and mental clarity, thanks to ketones fueling the brain

Some people even describe the experience as a brain "upgrade."

Don’t Forget Hydration

Skipping food doesn’t mean skipping fluids. Proper hydration is non-negotiable during fasting. Stick to:

• Plain water
• Black coffee (unsweetened)
• Herbal or unsweetened teas
• Electrolytes (if needed)

Hydration supports metabolism, prevents headaches, and helps your body function smoothly during the fast.

The Bottom Line

A 24-hour fast isn’t just “not eating.” It’s a remarkable biological reset that switches your fuel source, cleans up damaged cells, and rebalances hormones. While the potential benefits are impressive, always consult a healthcare professional before starting, especially if you have existing conditions.Your body is far more adaptive and resilient than you may realize – give it space, and it just might surprise you.