The Many Advantages of Fasting: Insights from Dr. Jason Fung

Guest Author: Dr. Jason Fung, Nephrologist and NY TImes Best Selling Author

Dr. Jason Fung is a nephrologist, functional medicine advocate, and New York Times best-selling author. His pioneering books, including "The Obesity Code" and "The Diabetes Code," challenge conventional medical perspectives on chronic diseases, advocating for, and introducing, dietary strategies like fasting to manage and even reverse them. As the co-founder of The Fasting Method, he provides education, tools and community to successfully implement intermittent fasting.

Many people have heard about the benefits of fasting and are curious about trying it, especially for weight loss. However, it can provide health benefits that go beyond that to include improved metabolic health and increased energy - and I am a big advocate of it.

You may wonder, what is fasting exactly? In short, fasting is simply a transition between storing energy and using energy - and it is one of the most effective ways to support your body’s natural energy balance. When you’re not eating, you’re not consuming calories, but your body still needs fuel and so uses stored glucose first, then when it runs out, taps into stored body fat for energy.

Our bodies are naturally designed for periods of fasting—after all, "breakfast" comes from breaking the overnight fast. In recent history, people followed an eating window of 10-12 hours, with 12-14 hours of fasting in between. Even further back, there could be much longer periods of time between eating. Today, fasting takes many forms, from time-restricted eating (TRE) to prolonged fasting, and the best approach is the one that fits your lifestyle.

Some examples of fasting styles include 12:12 Circadian Rhythm Pattern which limits your daily eating window from sunrise to sundown (ex: 7am-7pm), aligning with your body’s internal clock, known as circadian rhythms, supporting digestion, metabolism, and hormonal balance. 16:8 Time-Restricted Eating (TRE) involves a 16-hour fasting window with an 8-hour eating period, such as 11 AM - 7 PM. This is one of the easiest and most sustainable fasting methods. Prolonged Fasting (48+ Hours) enhances fat burning and metabolic benefits, as well as prompting deep cellular clean-up, known as autophagy. Longer fasts should be done periodically and with medical guidance if taking medications. Prolon’s 5-Day Fasting Mimicking Diet (FMD) provides the benefits of prolonged fasting while maintaining nourishment. Other fasting variations include the 5:2 approach, where calorie intake is restricted on two non-consecutive days per week, and One Meal a Day (OMAD), where all daily calories are consumed in a single sitting.

There are many advantages of fasting. Here are five key ones:

Top Advantages of Fasting 

• Physical Benefits
  The benefits of fasting go beyond weight loss and weight management. They can include improvements in energy levels, sleep, metabolic markers (such as supporting healthy blood sugar, insulin sensitivity, and cholesterol levels), reduced inflammation, and even enhanced longevity. 
  
  
• Can be incorporated into any diet
  No matter your dietary preferences or guidelines—whether it's vegan, keto, low-carb, gluten-free, or anything in between—fasting is about when you eat, not what you eat, making it easily integrated into any diet. 
  
  
• Flexibility
  Fasting puts you in control—you choose when and how to do it. It’s flexible, allowing you to adjust your schedule based on your lifestyle, whether that means fasting on certain days, taking breaks, or extending your fasts. 
  
  
• Cost-effective
  Fasting can cost little to nothing—in fact, it saves you money by reducing grocery expenses. Your body already has stored energy in the form of fat, and fasting simply allows you to tap into those reserves for fuel. 
  
  
• Simple & Convenient
  Fasting is one of the easiest ways to manage your diet, as there are no complicated rules, calorie counting, or ingredient tracking. You simply choose when not to eat. It’s accessible to anyone, anywhere, at any time. It's also incredibly convenient. You don’t have to plan meals, cook, or clean up, making fasting a way to simplify both your diet and your daily routine.

Incorporating fasting into your lifestyle can be one of the simplest yet most powerful ways to support your health. Whether you're looking to improve metabolic health, lose weight, or increase energy, fasting offers a flexible, cost-effective, and accessible approach. The best part? It doesn’t require drastic changes to what you eat—just when you eat.