Fasting has become a bit of a ‘buzzword’ within the dieting industry. It involves partaking in periods of food abstinence. This is a relatively modern adoption into the world of health, in other cultures it has been done for many years for cultural and religious practices.
History of Fasting
History can trace fasting back to around the 5th Century in which Hippocrates recommended abstinence from food as a treatment for conditions. Whereas ancient religions including Buddhism, slam, Judaism, Taoism, Jainism, and Hinduism all commonly practice fasting as a religious practice. For example, taking part in Ramadan brings Muslims closer to Allah. Fasting is part of the five pillars of Islam. Whereas in Judaism, the religious holiday of Yom Kippur where fasting is encouraged as a way of repenting for your sins during a period of reflection.
It is important to note that fasting for religious practices and fasting made popular for weight loss are very different. Fasting diets are typically fads, whereas religious fasting is a widely respected and valued part of culture.
Here are a few examples of popularised diets that include elements of fasting:
- The 5:2 Fast
- The 16:8 Fast
- Intermittent Fasting
- Time Restricted Eating
- Overnight fasting
- Juice fasting
Intermittent fasting is one of the most popular forms of fasting. This includes intermittently restricting food for specific times of the day. For example, the 16:8 fast means eating for 8 hours of the day and fasting for the remaining 16 hours. This may look like eating breakfast at 11am and cease eating at 7pm, Or eating breakfast at 7am and cease eating at 3pm
What happens during a fast?
When a human eats a standard 3 meals a day their body maintains its normal physiology and energy levels by utilising blood glucose. Whereas, when a person fasts, they are dependent on limited glycogen stores in the liver and muscles, as well as fat storage. It depends on the person, however, reaching a fasted state can occur anywhere between 12-24 hours. In a textbook example, most people are in a fasted state within 24 hours and glycogen has depleted. During this time, the body uses fat storage in a process called gluconeogenesis which converts free fatty acids into glucose and ketones. Glucose can then be used to energise the body.
What are the benefits of fasting?
The researched benefits of fasting include:
- Life longevity (only found in animal studies)
- Weight loss
- Improved cholesterol
- Improved blood pressure
- Improved blood glucose
- May improve brain function and performance
Be mindful that as fast should not be undertaken without the supervision of a doctor or other healthcare professional such as a Dietitian or Accredited Nutritionist.
If you are to undertake a supervised fast be aware that some medications require you to have eaten before taking the medication.