From the Guidelines
Intermittent fasting has a long history dating back thousands of years, with roots in religious, spiritual, and health practices across many cultures, as noted in a recent review of dietary recommendations for diabetes management 1.
History of Intermittent Fasting
The history of intermittent fasting is complex and multifaceted, with various forms of fasting practiced for different purposes.
- Ancient healing traditions in Greece, including Hippocrates, recommended fasting for certain illnesses.
- Religious fasting traditions appear in Christianity (Lent), Islam (Ramadan), Judaism (Yom Kippur), and Buddhism, with each having its unique duration, frequency, and type of fast, as discussed in a study on the impact of Christian Orthodox Church dietary recommendations on metabolic syndrome risk factors 1.
- Modern scientific interest in intermittent fasting began in the early 1900s when researchers observed that caloric restriction extended lifespan in laboratory animals, as referenced in a review of time-restricted eating for obesity prevention and treatment in youth 1.
Evolution of Intermittent Fasting Research
In the 1940s, studies showed fasting's potential benefits for epilepsy management, while the 1960s saw research on alternate-day fasting.
- The 2000s brought renewed scientific attention with studies on various fasting protocols like time-restricted eating (16:8 method), alternate-day fasting, and the 5:2 diet.
- Dr. Michael Mosley popularized intermittent fasting through his 2012 BBC documentary and subsequent books, contributing to its growing popularity.
Current State of Intermittent Fasting
Today, intermittent fasting continues to be studied for its potential benefits on weight management, metabolic health, cellular repair processes, and longevity, though research is still evolving regarding optimal protocols and long-term effects, as noted in a recent review of facilitating positive health behaviors and well-being to improve health outcomes in diabetes care 1.
- A 2024 systematic review and meta-analysis of RCTs examining both partial and total meal replacements concluded that intermittent energy restriction produces small but significant reductions in waist circumference and fat-free mass but were otherwise not superior to conventional meal plans, as discussed in a study on the impact of Christian Orthodox Church dietary recommendations on metabolic syndrome risk factors 1.
- The effects of intermittent fasting on human health are still being researched, with some studies suggesting benefits for metabolic syndrome risk factors, such as reduced blood pressure, improved glucose metabolism, and increased fat loss, as referenced in a review of integration of time-based recommendations with current pediatric health behavior guidelines 1.
From the Research
History of Intermittent Fasting
- The practice of fasting, including intermittent fasting, has been around for centuries and has been used for various purposes, including political, religious, and therapeutic reasons 2.
- Early studies on fasting date back to 1982, which described the physiological effects of fasting, including rapid weight loss, negative sodium balance, and changes in hormone levels 2.
- More recent studies have focused on the effects of intermittent fasting on glucose and lipid metabolism, insulin resistance, and blood pressure in patients with metabolic syndrome and type 2 diabetes 3, 4.
Physiological Effects of Fasting
- Fasting is characterized by a high rate of gluconeogenesis, with amino acids as the primary substrates, and progressive ketosis due to the mobilization and oxidation of fatty acids 2.
- As ketone levels rise, they replace glucose as the primary energy source in the central nervous system, decreasing the need for gluconeogenesis and sparing protein catabolism 2.
- Hormonal changes occur during fasting, including a fall in insulin and T3 levels and a rise in glucagon and reverse T3 levels 2.
Therapeutic Effects of Intermittent Fasting
- Intermittent fasting diets have been shown to have therapeutic effects on blood glucose and lipids in patients with metabolic syndrome and significantly improve insulin resistance 3.
- A systematic review and meta-analysis found that intermittent fasting diet intervention reduced fasting blood glucose, glycosylated hemoglobin, insulin plasma levels, and HOMA-IR, and also decreased BMI, body weight, and waist circumference 3.
- However, other studies have found that high-protein diets, which are often used in conjunction with intermittent fasting, do not significantly improve glycemic control and blood pressure, but can lower LDL, TC, TG, and HOMA-IR levels in type 2 diabetes patients 4.