What Is 36 Hours of Fasting?

Fasting—it’s a word that either excites you or makes you want to run in the opposite direction. But let’s talk about the 36-hour fast, a kind of middle ground between intermittent fasting and those hardcore extended fasts that last multiple days. It’s long enough to shake things up inside your body but not so extreme that you feel like you’ve time-traveled back to the caveman era.

Highlights 

• A 36-hour fast involves eating dinner on Day 1, skipping meals on Day 2, and breaking the fast at breakfast on Day 3.

• It allows the body to reset, shifting from burning glucose to fat metabolism and triggering autophagy (cellular cleanup).

• Benefits include insulin reduction, fat burning, mental clarity, and increased growth hormone production.

• Hunger pangs and low energy can hit hard initially, but hydration and electrolytes help manage discomfort.

• It forces a mindset shift, helping you differentiate between real hunger and habitual eating.

• Ideal for those seeking metabolic benefits, but not recommended for people with eating disorders, chronic illness, or uncontrolled blood sugar issues.

• Fasting isn’t about starving—it’s about giving your body a break and understanding how it functions.

• If you practice intermittent fasting, you can track your sugar spikes with CGM and log food intake in the trst app to optimize your results.

Breaking It Down

A 36-hour fast is exactly what it sounds like—no calories, just good old-fashioned patience and hydration. Typically, you eat dinner on Day 1, skip meals on Day 2, and break your fast at breakfast on Day 3. It’s a cycle that gives your digestive system a serious break and lets your body shift gears into deep repair mode. Think of it as hitting the reset button but without the annoying loading screen.

What’s the Point of This?

So why go for a 36-hour fast when shorter fasts (like 16:8 or even 24-hour ones) exist? Well, this one hits a sweet spot. It’s long enough to trigger autophagy—a fancy word for your cells cleaning out junk—but short enough that it doesn’t completely drain you. You’re likely to burn through glycogen stores and enter full-on fat-burning mode, but you won’t be so depleted that you start questioning your life choices.

On a more personal level, fasting like this forces you to rethink your relationship with food. Are you actually hungry, or are you just used to eating at certain times? Do you eat because you need fuel or because you’re bored? A 36-hour fast doesn’t just reset your metabolism; it resets your mindset too.

What Happens in Your Body?

The first 12 hours? Pretty normal. Your body is still running on stored glucose. Then things start shifting. By the 18-hour mark, your insulin levels drop, and your body begins tapping into fat for energy. Once you cross the 24-hour line, autophagy kicks in, clearing out old, damaged cells. This is when the real magic happens.

At around 30-36 hours, growth hormone surges, helping with muscle preservation and fat metabolism. Some people describe this phase as an almost euphoric experience—sharper focus, better mood, and a sense of mental clarity that’s hard to find in the middle of a normal food-filled day.

Will You Feel Like a Superhuman—or a Zombie?

Let’s be real—not everyone coasts through this fast effortlessly. The first few times can feel brutal. Hunger pangs, low energy, maybe even irritability (aka hanger in full force). But if you’re used to fasting, it might feel surprisingly manageable, even freeing. A lot of it comes down to mindset and preparation. Stay hydrated, get enough electrolytes, and keep yourself distracted—because watching food videos on Instagram while fasting? Bad idea.

Who Should—and Shouldn’t—Try It?

If you’re healthy, curious, and want to test your limits, a 36-hour fast can be a powerful tool. But if you have a history of disordered eating, chronic illness, or blood sugar issues, this isn’t the experiment to jump into blindly. Always check with a healthcare pro before diving in. And if your body is screaming at you to stop? Listen to it. There’s no prize for fasting the longest.

Is It Worth Trying?

The 36-hour fast isn’t about starving yourself—it’s about resetting, recharging, and giving your body a break. Some people swear by it as a mental and physical boost, while others decide it’s not their cup of tea (or black coffee, since that’s all you can have while fasting). The only way to know? Try it and see how your body reacts. If it works for you, great. If not? No harm, no foul.

And if you’re into intermittent fasting, keeping track of how your body responds is key. trst health makes that easier with CGM (Continuous Glucose Monitoring), which helps you check your sugar spikes in real time. You can also use food logging in the trst app to see exactly how your meals impact your blood sugar levels. So whether you're experimenting with fasting or fine-tuning your diet, a little data can go a long way in helping you make informed choices.

References

1. 10 Benefits of 36 Hour Fasting As A Habit Pattern - Mimio Health

2. Is Monk Fast Effective for Weight Loss? All You Need to Know

3. Twice-Weekly 36-Hour Intermittent Fasting Practice

4. Intermittent Fasting: What is it, and how does it work?