Intermittent Fasting for Blood Sugar Control

Who Is Jason Fung? His Groundbreaking Perspective

Dr. Jason Fung is a nephrologist from Canada and a leading authority in the field of intermittent fasting. His breakthrough approaches in treating diabetes and obesity are transforming the medical community’s understanding of metabolic diseases. Dr. Fung’s core view is that type 2 diabetes is essentially a “curable” disease, not a chronic condition requiring lifelong medication.

Traditional medical views consider type 2 diabetes a progressive disease—patients’ pancreatic function gradually declines, eventually requiring insulin therapy. But Dr. Fung believes this “progressive deterioration” view is wrong. By reducing insulin usage (through fasting), allowing the pancreas to rest, pancreatic function can potentially recover. This perspective challenges the traditional treatment paradigm and brings new hope to countless diabetes patients.

Dr. Fung’s book “The Diabetes Code” has been translated into multiple languages since publication and become a global bestseller. His method doesn’t rely on expensive drugs or complex medical equipment but on adjusting eating habits, making his approach highly accessible and replicable.

Insulin Resistance Mechanism

The Core of The Diabetes Code: The Truth About Insulin Resistance

The core concept of “The Diabetes Code” is “insulin resistance.” Dr. Fung explains that insulin resistance is essentially the body becoming less responsive to insulin—much like a hard-of-hearing person needs others to speak louder—the pancreas must secrete more insulin to lower blood glucose. When this continues, the pancreas eventually becomes “exhausted” and cannot secrete enough insulin, causing persistently elevated blood glucose.

What causes insulin resistance? Dr. Fung believes the primary cause is long-term excessive carbohydrate intake. When we consume large amounts of carbohydrates, blood glucose rises rapidly, and the pancreas secretes insulin to lower it. Chronically elevated insulin levels cause cells to develop resistance to insulin—a self-protective mechanism of the human body—cells don’t want to be “overstuffed,” so they reduce their response to insulin.

The key to solving this problem lies in lowering insulin levels. Dr. Fung presents a simple but profound logic: if we reduce carbohydrate intake, insulin levels decrease; when insulin levels decrease, cell sensitivity to insulin recovers; when sensitivity recovers, blood glucose naturally drops. This logic appears simple but is supported by extensive clinical research.

The Scientific Principle of Intermittent Fasting

Intermittent fasting is the core method recommended by Dr. Fung. Its principle is to extend the period without food, keeping the body’s insulin levels consistently low, giving the pancreas and cells “rest” and “repair” opportunities. Common intermittent fasting methods include:

5:2 Fasting: Normal eating for 5 days, 2 days significantly reduced calorie intake (typically only 500-600 calories). This method is relatively gentle, suitable for those just starting to try fasting.

16:8 Fasting: Eating only within an 8-hour window daily, fasting for the remaining 16 hours. For example, eating the first meal at noon and the last meal at 8 PM, then no more food. This is one of the most popular fasting methods today.

24-hour Fasting: Choosing 1-2 days per week to fast completely, only drinking water. This method has stronger effects and is suitable for those with some fasting experience.

Extended Fasting (2-5 days): Conducting longer fasts under medical supervision. This method is typically used to reverse severe metabolic diseases and requires medical guidance.

During fasting, the body initiates “autophagy”—the process of cells cleaning up damaged proteins and old organelles. This process not only helps improve insulin sensitivity but also has anti-aging and anti-inflammatory effects.

Precautions During Fasting

Although intermittent fasting works for many people, it’s not suitable for everyone. Before starting fasting, several points need attention:

Consult a Doctor: Especially for patients taking glucose-lowering drugs or insulin, fasting may cause hypoglycemia, requiring medication adjustment under doctor’s guidance.

Progressive Approach: Don’t start with long-duration fasting immediately. It is recommended to start with 12-hour fasting, gradually extending to 16 hours, 18 hours, until 24 hours.

Stay Hydrated: Ensure adequate water intake during fasting—at least 2 liters of water daily. You can drink tea, coffee (without sugar and creamer), and other zero-calorie beverages.

Pay Attention to Body Signals: If symptoms of hypoglycemia (dizziness, heart palpitations, cold sweat, etc.) occur, eat immediately and seek medical attention.

Avoid Intense Exercise: Physical strength decreases during fasting—high-intensity exercise should be avoided. Gentle exercises like walking, yoga, and tai chi are suitable choices.

Dietary Coordination: Eating Right Is More Important Than Eating Less

Dr. Fung emphasizes that what you eat during fasting is equally important. He recommends a “low-carbohydrate diet”—significantly reducing intake of refined carbohydrates like rice, noodles, and sugar, while increasing protein and healthy fat intake.

Recommended Foods: Meat, fish, eggs, nuts, avocados, leafy greens, berries, etc. These foods have minimal impact on blood glucose and provide lasting satiety.

Foods to Avoid: White rice, white flour, bread, candy, sugary drinks, potatoes, etc. These foods rapidly raise blood glucose, counteracting the effects of fasting.

Foods in Moderation: Whole grains, legumes, sweet potatoes, etc. Although these foods contain carbohydrates, they contain more fiber, with relatively smaller impact on blood glucose.

Dr. Fung also specifically mentions there’s no need to obsessively count calories. What’s important is controlling carbohydrate quantity, not precisely calculating calories per meal. When carbohydrate intake is reduced, total calorie intake naturally decreases.

Frequently Asked Questions

Q1: Will fasting cause hypoglycemia?

It is possible, especially for patients taking glucose-lowering drugs or insulin. Be sure to consult a doctor before fasting and adjust medications under their guidance. If hypoglycemia symptoms (dizziness, heart palpitations, cold sweat, etc.) occur during fasting, eat immediately.

Q2: Can I exercise during fasting?

Gentle exercise like walking, yoga, and tai chi is acceptable. However, high-intensity strenuous exercise should be avoided because physical strength decreases during fasting—forcing exercise may cause hypoglycemia or fainting.

Q3: How long does it take to see results from fasting?

Results vary from person to person. Some may see blood glucose improvement within a few weeks, others may need a few months. What’s important is persistence—it is usually recommended to evaluate effects after at least 3 months of commitment.

Q4: Can pregnant and breastfeeding women fast?

Not recommended. Pregnant and breastfeeding women need extra nutrition to support fetal or infant development and should not fast.

This content is for reference only and cannot replace professional medical advice. For health concerns, please consult your doctor. Discuss any diet or exercise plan with your doctor before implementation.