Rob's Medical Notes on 24 Hour Fasting

Introduction

A 24-hour fast can have significant effects on your body. While fasting, your body undergoes various metabolic shifts, including using different energy sources and adjusting to the absence of food. This guide will explain how your body responds to a 24-hour fast, how to prepare for it, and what foods and drinks are best when breaking your fast.

How the Body Reacts to a 24-Hour Fast

When you fast for 24 hours, your body goes through several phases, from using glycogen stores for energy to entering ketosis and eventually breaking down fat for fuel. Here’s a breakdown of the stages:

• First 12-16 Hours: Glycogen Use

Initially, your body relies on glycogen—stored carbohydrates in the liver and muscles. This energy source is sufficient for the first 12-16 hours of fasting.

• After 16 Hours: Transition to Fat Burning

Once glycogen stores are depleted, your body shifts to burning fat for energy. This process leads to the production of ketones, an alternative energy source that helps you maintain energy levels during fasting.

• 24-48 Hours: Minimal Protein Breakdown

After about 24 hours, your body may start breaking down small amounts of muscle protein for fuel, but this is minimal, especially if you are nourishing your body during your eating window.

• Impact on Blood Sugar Levels

Blood sugar naturally drops during a 24-hour fast, causing the body to shift to fat burning. This drop may lead to fluctuations in energy and mood, which can be managed with proper nutrition when breaking the fast.

How to Best Prepare for a 24-Hour Fast

Proper preparation is crucial for ensuring the fast goes smoothly and your body responds effectively. Here’s what you can do:

• Eat a Balanced Meal Before Starting the Fast:

• Focus on Protein: Ensure your pre-fast meal contains adequate protein, like chicken, fish, tofu, or legumes. Protein helps stabilize blood sugar and keeps you full longer.

• Incorporate Healthy Fats: Foods like avocado, olive oil, or nuts help slow digestion and provide sustained energy throughout the fasting period.

• Include Fibre: Vegetables, fruits, and whole grains like quinoa or oats are excellent sources of fibre, which helps keep your blood sugar steady and promotes digestion.

• Stay Hydrated: Drink plenty of water leading up to the fast—aim for 2-3 litres. You can also consume electrolyte-rich drinks (without added sugars), such as coconut water, to help balance electrolytes.

• Avoid High-Carb Foods: Refined carbohydrates (like white bread, pastries, and sugary snacks) should be avoided, as they can cause rapid blood sugar spikes followed by crashes, making fasting more difficult.

• Rest Well the Night Before: Ensure you get 7-8 hours of sleep before starting your fast. Rest helps manage hunger and fatigue during the fast.

What to Eat or Drink When Breaking the Fast

When it’s time to break your fast, how you reintroduce food matters. Consuming the right foods will help stabilize your blood sugar, prevent digestive discomfort, and support muscle maintenance. Here are some key considerations:

• Break the Fast with a Nutrient-Dense Meal:

• Focus on Protein: Protein-rich foods like lean meats, tofu, eggs, or legumes are essential to prevent muscle breakdown, stabilize blood sugar, and promote muscle recovery.

• Incorporate Healthy Fats: Include healthy fats like avocado, olive oil, or nuts. Fats slow digestion and help provide sustained energy.

• Fibre-Rich Foods: Include vegetables, fruits, or whole grains to ensure a steady release of glucose into the bloodstream and to support healthy digestion. fibre helps avoid blood sugar spikes and digestive discomfort.

• Avoid High-Glycemic Foods:

• Why? High-carb foods like white bread, sugary snacks, or processed foods can cause rapid blood sugar fluctuations, leading to energy crashes and fatigue.

• Best Option: Stick to whole foods such as vegetables, legumes, and whole grains to provide lasting energy without spikes.

• Stay Hydrated:

• Drink Water: After fasting, it’s easy to become dehydrated, so drink plenty of water when breaking your fast. Consider adding a pinch of salt to water or drinking an electrolyte beverage to maintain hydration and balance.

• Eat Slowly and Mindfully:

• Why? After a fast, your digestive system may be sensitive. Eating slowly allows your stomach to adjust and prevents overeating, which can lead to bloating or discomfort.

Top Tips for Successfully Completing a 24-Hour Fast

• Stay Hydrated

• Drink 2-3 liters of water daily, including herbal teas like peppermint or ginger, which can aid digestion.

• Consider electrolyte supplementation (a pinch of salt or an electrolyte drink) to maintain balance.

• Avoid High-Carb Meals When Breaking the Fast

• Opt for meals rich in protein, healthy fats, and fiber, such as grilled chicken with vegetables, avocado, and quinoa.

• Avoid sugary snacks, processed foods, and high-carb meals that can spike blood sugar.

• Eat Mindfully After Your Fast, don't rush your meal!

• Break your fast with a balanced meal that includes protein, healthy fats, and fibre to stabilize blood sugar.

• Include nutrient-dense plant-based foods for antioxidants and anti-inflammatory benefits.

• Limit Caffeine Intake

• Stick to black coffee or unsweetened tea to avoid blood sugar spikes from added sugars or creamers.

• Limit caffeine to 1-2 cups per day to avoid feelings of jitteriness or anxiety.

• Monitor Your Symptoms

• Hunger: Stay hydrated with water or herbal teas. Light activities can help distract you from hunger.

• Fatigue: Ensure you get adequate sleep (7-8 hours) and stay hydrated to manage fatigue.

• Headaches: Drink plenty of water and balance caffeine intake to avoid dehydration.

• Dizziness: Drink water, consider adding electrolytes, and break your fast with a balanced meal.

• Irritability: Break your fast with a nutrient-dense meal that includes protein and healthy fats.

• Eat Slowly and Avoid Overeating

• Eating large portions after a fast can overwhelm your digestive system. Instead, eat slowly and avoid overeating to prevent discomfort.

• Stay Active, But Keep It Light

• Engage in light physical activities, like walking or stretching, to promote circulation and avoid stiffness.

• Avoid intense exercise while fasting to minimize fatigue.

• Prioritize Sleep and Rest

• Aim for 7-8 hours of sleep to help your body recover and maintain energy during the fast.

• Listen to Your Body

• If you feel excessively tired, dizzy, or unwell, adjust your fasting routine. Consider consulting a healthcare provider if symptoms persist.

• Be Patient and Adjust Gradually

• The first few days of fasting may be challenging. Gradually extend your fasting periods or adjust meal timing to ease into the routine.

Rob has branched out from working as a GP into functional medicine. You can see more about what he does >here<.