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For thousands of years, people of nearly every culture have practised fasting for spiritual or health reasons. Ancient fasting first appeared around 1,500 BC with the Vedic, Hindu, and Jainism religions. Fasting on designated holy days was frequent to reduce the burden and harm harvesting and eating caused for animals and plants. In Buddhism, the practice of intermittent fasting restricts eating to a specific period. Fasting for religious reasons was also prevalent in other parts of the ancient world, including India, China, the Middle East, and Greece. For example, Muslims worldwide observe Ramadan, a month-long religious period that includes fasting from sunrise to sunset.

Fasting was also considered an effective treatment for health conditions ranging from acute infection to allergies and diseases resistant to treatment. By the 19th and 20th centuries, the science of fasting was used to help treat many conditions, including arthritis, asthma, chronic fatigue, high blood pressure, lupus, Crohn’s disease and irritable bowel. Before insulin became available in the early 20th century, physicians recommended fasting and calorie-restricted diets to treat type 1 diabetes.

Today, fasting is commonly used for blood glucose and lipid markers in laboratory tests to aid in the diagnosis of diseases as well as assessing any risk factors. However, the potential of fasting to help reduce the risk of and potentially reverse type 2 diabetes has only recently started gaining recognition in the medical community and beyond.

Advances in diabetes management

Diabetes management has evolved from merely focusing on managing glucose levels to a more comprehensive approach encompassing heart, kidney and nerve health with overall well-being. Additionally, the advent of diabetes technology, such as insulin pumps and continuous glucose monitoring (CGM), has revolutionised diabetes management, while innovative oral agents like SGLT2 inhibitors that lower glucose levels and GLP-1 agonists that inhibit the release of glucagon and stimulate insulin production have proven effective in treating type 2 diabetes.

Nonetheless, these advancements, while improving the quality of life for people with diabetes, have not been able to curb the rise of type 2 diabetes. This has led to a change in thinking toward preventing and reversing the condition, with fasting emerging as an important tool in this new approach.

Advancements in diabetes management have improved the lives of people with diabetes but have not slowed the rise of type 2 diabetes, bringing a shift towards preventing and reversing the condition, with fasting recognised as a possible solution.

The fascinating science behind fasting

How does fasting work to potentially prevent or reverse type 2 diabetes? During the first three days of fasting, the body mobilises all the glucose for energy. Once there is no more glucose, the body uses ketone bodies, energy sources from fat produced by the liver. Glucagon, a hormone produced by the pancreas to regulate blood glucose levels, helps to break down fat to create ketones for energy. From day four onwards, the body mobilises fat in the liver and pancreas and visceral fat.

The hormone glucagon further elevates the benefits of fasting by preventing glucose levels from dropping too low. Alpha cells in the pancreas produce glucagon and release it in response to a drop in glucose, prolonged fasting, exercise and protein-rich meals. Glucagon helps break down fat, particularly in the pancreas, liver and visceral areas.

Benefits and types of fasting

Since 2020, studies have shown that fasting can be a targeted, efficient and sustainable way to reduce the risk of and treat type 2 diabetes. Benefits include improved insulin sensitivity, lowered blood pressure, reduced body fat and risk of CVD. One study showed that fasting, accompanied by regular physical activity, could potentially reverse the condition for 60% of people living with type 2 diabetes for over five years. However, sustaining a healthy lifestyle is essential, or the diabetes will return.

Different types and lengths of fasting have been shown to have benefits. Intermittent fasting, which involves alternating cycles of fasting and eating, can help control calorie intake and encourage the body to use stored fat for energy, improving metabolic health. Common variations include the 16/8 (restricting food intake to an 8-hour window each day) and 5:2 (fasting for two days a week) methods. Regular prolonged fasting, lasting anywhere from 24 hours to several days, has been shown to induce metabolic changes that may offer protective effects against type 2 diabetes.

Fasting can be a targeted, efficient and sustainable way to prevent and treat type 2 diabetes. Benefits include improved insulin sensitivity, lowered blood pressure, reduced body fat and risk of CVD.

Points to consider before fasting

Fasting may not be suitable for everyone. Therefore, before starting a fast, it is important to consult a healthcare professional to understand the potential risks and complications and create a plan to manage the fast effectively. For people with diabetes, fasting can increase the risk of health problems such as low or high glucose levels, diabetic ketoacidosis (DKA) and dehydration. These risks stem from reduced food and fluid intake and meal timing. Discussing medication adjustments and monitoring glucose levels should also be part of the conversation with a healthcare professional.

The future of fasting

We have known about fasting for 4,000 years but are yet to fully take advantage of its potential to reduce the impact of chronic health conditions like diabetes. By embracing fasting as part of a comprehensive lifestyle change, we can help pave the way for a healthier future.

Free Online Course : Diabetes and Ramadan Practical Guidelines 2021

This online course for healthcare professionals outlines the key factors that help people with diabetes fast during Ramadan. You will learn about conducting pre-Ramadan assessments to determine appropriate management strategies, including medication management, for high-risk individuals. Learn more

This article does not intend to replace professional medical advice. Always consult your healthcare provider before starting a new health regimen, especially if you have a medical condition such as diabetes.


Justine Evans is Content Editor at the International Diabetes Federation

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