The Science Behind 36-Hour Fasting

Ever wondered what happens to your body when you fast for 36 hours? After roughly 12 hours without food, your body's glycogen stores—essentially stored sugar—begin to dwindle. Gastroenterologist Dr. Sudeep Khanna explains that as glycogen depletes, insulin levels plummet, which is crucial because high insulin can encourage fat storage. With lower insulin, your body shifts into fat-burning mode, using stored fat for energy.

Once you hit around 18 to 24 hours, your body transitions to breaking down fat into molecules like fatty acids and ketones. This state, known as ketosis, allows your brain and body to function without a food source. Plus, after about 24 to 36 hours of fasting, a process called autophagy kicks in, where your body cleans out old, damaged cells, a process that could potentially ward off diseases such as cancer and Alzheimer’s, although more research is needed.

The Fast and Feel: Focus vs. Fatigue

Many people report enhanced focus during fasting, likely due to stable blood sugar levels and reduced digestive workload. However, some also experience tiredness and irritability at the start of their fast. Dr. Khanna notes that feelings of hunger tend to peak around the times you normally eat but often fade after 18 to 24 hours as fluctuations in the hunger hormone ghrelin occur.

Is 36-Hour Fasting Safe?

According to Dr. Khanna, this fasting schedule can be safe for most healthy adults—provided they're hydrated and not overexerting themselves. However, those with diabetes, eating disorders, pregnant individuals, or anyone on specific medications should avoid this fasting regimen unless monitored by a healthcare professional.

The Hidden Risks of Extended Fasting

Dr. Chaturvedi warns about the potential dangers of prolonged fasting. While your body starts burning fat for energy, excess ketones can lead to an acidic state. Dehydration also poses risks like electrolyte imbalances, which explain the dizziness and headaches many experience initially. More concerning, however, are the risks of muscle loss, digestive problems, mood swings, and inflammation.

To Binge or Not to Binge: Finding the Balance

Both Dr. Khanna and Dr. Chaturvedi caution against binging after fasting. Dr. Khanna emphasizes the need to monitor metabolism, as extended fasting might train your body to store more fat in a starvation response. Alternatives like intermittent fasting with broader eating windows may offer a more sustainable approach.

In summary, while a 36-hour fast can indeed help with weight loss, it comes with its own set of challenges. Learning how to navigate those—and maintaining a balanced approach—might be key to achieving your health goals.