A viral 55-second simulation video from Wellness Wise shows the dramatic changes your body undergoes during a 36-hour fast. Within just four hours, digestion halts and your body enters a ‘catabolic phase,’ breaking down stored energy. By eight hours, blood sugar drops, and glycogen stores are used for energy.

After 12 hours, the body begins burning fat for fuel through a process called metabolic switching. By 16 hours, autophagy kicks in—where cells clean and repair themselves. At 24 hours, the body is in full fat-burning mode, reducing inflammation and improving insulin response.

At the 30-hour mark, growth hormone surges, helping preserve muscle and promote deeper healing. By 36 hours, maximum autophagy is reached, aiding tissue regeneration and boosting metabolism.

Despite the hype, experts remain divided. “A lot of the research hasn’t really been borne out in human beings,” says Professor James Betts. Others, like Dr. Mark Mattson, argue fasting protects against chronic disease.

Important: Fasting isn’t for everyone. Always consult a healthcare professional before starting.