Intermittent fasting

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Intermittent fasting (IF) is an umbrella term for various diets that cycle between a period of fasting and non-fasting during a defined period. Intermittent fasting can also be used with calorie restriction for weight loss.[1]


  • 1 Practice and variations
  • 2 Research
  • 3 See also
  • 4 References

Practice and variations[edit]

Some people may use intermittent fasting to diminish caloric intake and lose weight.[2][3] Preliminary research indicates that intermittent fasting may affect risk factors for some diseases.[3]

Intermittent fasting protocols can be grouped into 2 categories: whole-day fasting and time-restricted feeding (TRF).

  • Whole-day fasting involves regular one-day fasts. The strictest form would be Alternate day fasting (ADF). This involves a 24-hour fast followed by a 24-hour non-fasting period.[4] The 5:2 diet allows the consumption of 500–600 calories on fasting days.[5][6]
  • Time-restricted feeding (TRF) involves eating only during a certain number of hours each day.[7] A common form of TRF involves fasting for 16 hours each day and only eating during the remaining 8 hours, typically on the same schedule each day.[8] A more liberal practice would be twelve hours of fasting and a twelve-hour eating window, or a stricter form would be to eat one meal per day, which would involve around 23 hours of fasting per day.[9]

Recommendations vary on what can be consumed during the fasting periods. Some would say only water, others would allow tea or coffee (without milk or sugar) or zero-calories drinks with artificial sweeteners. Yet others would allow “modified fasting” with limited caloric intake (e.g., 20% of normal) during fasted periods rather than none at all.[4]

The 5:2 diet became popular in the UK in 2012[10][11][12] after the BBC2 television Horizon documentary Eat, Fast and Live Longer.[13] Via sales of best-selling books, it became widely practiced.[6][14]

According to NHS Choices as of 2012, people considering the 5:2 diet should first consult a physician, as fasting can sometimes be unsafe.[6][15] In the UK, the tabloid press reported on research claiming the 5:2 diet could reduce the risk of breast cancer, improve brain and immune functions, or extend lifespan, but there is inadequate evidence for such statements.[6][16] A news item in the Canadian Medical Association Journal expressed concern that promotional material for the diet showed people eating high-calorie food such as hamburgers and chips, and that this could encourage binge eating since the implication was that “if you fast two days a week, you can devour as much junk as your gullet can swallow during the remaining five days”.[17]


A 2014 review described that intermittent fasting has not been studied in children, the elderly, or the underweight, and could be harmful in these populations.[18] It also suggested that people choosing to fast for periods of time greater than 24 hours should be monitored by a physician, as changes to the gastrointestinal system or circadian rhythm can occur.[18] The review concluded that fasting is unlikely to have much effect on conditions other than obesity, such as aging or other chronic conditions, unless combined with long-term calorie restriction and a plant-based diet, such as the Mediterranean diet.[18]

According to another 2014 review, intermittent fasting can lead to weight loss, though long-term calorie restriction can lead to slightly more weight loss compared to intermittent fasting.[19] Intermittent fasting has been found in healthy and obese adults to reduce basal insulin, triglycerides, and blood glucose in fasting periods shorter than 24 hours.[20] A 2014 review showed that intermittent fasting may reduce inflammation mechanisms and possibly affect cancer risk.[21] Reductions in weight, improvements in cardiovascular and metabolic variables, such as fat mass, LDL cholesterol, triglycerides, and C-reactive protein in non-obese individuals have been recorded.[22] Laboratory and preliminary human research indicates that intermittent fasting may influence metabolism of different food sources.[3][20]

See also[edit]

  • Calorie restriction
  • Henry S. Tanner (doctor)


  • ^ Mager, D. E (2006). “Caloric restriction and intermittent fasting alter spectral measures of heart rate and blood pressure variability in rats”. The FASEB Journal. 20 (6): 631–7. doi:10.1096/fj.05-5263com. PMID 16581971. 
  • ^ Patterson, R. E; Laughlin, G. A; Lacroix, A. Z; Hartman, S. J; Natarajan, L; Senger, C. M; Martínez, M. E; Villaseñor, A; Sears, D. D; Marinac, C. R; Gallo, L. C (2015). “Intermittent Fasting and Human Metabolic Health”. Journal of the Academy of Nutrition and Dietetics. 115 (8): 1203–1212. doi:10.1016/j.jand.2015.02.018. ISSN 2212-2672. PMC 4516560 . PMID 25857868. 
  • ^ a b c Mattson, M. P; Longo, V. D; Harvie, M (2017). “Impact of intermittent fasting on health and disease processes”. Ageing Research Reviews. 39: 46–58. doi:10.1016/j.arr.2016.10.005. PMC 5411330 . PMID 27810402. 
  • ^ a b Varady, K. A (2011). “Intermittent versus daily calorie restriction: Which diet regimen is more effective for weight loss?”. Obesity Reviews. 12 (7): e593–601. doi:10.1111/j.1467-789X.2011.00873.x. PMID 21410865. 
  • ^ Fisher, Roxanne (1 June 2016). “What is the 5:2 diet?”. BBC GoodFood, Worldwide. 
  • ^ a b c d Fleming, Amy (27 January 2015). “Fasting facts: is the 5:2 diet too good to be true?”. The Guardian. Retrieved 18 January 2018. 
  • ^ Rothschild, Jeff; Hoddy, Kristin K; Jambazian, Pera; Varady, Krista A (2014). “Time-restricted feeding and risk of metabolic disease: A review of human and animal studies”. Nutrition Reviews. 72 (5): 308–18. doi:10.1111/nure.12104. PMID 24739093. 
  • ^ Moro, Tatiana; Tinsley, Grant; Bianco, Antonino; Marcolin, Giuseppe; Pacelli, Quirico Francesco; Battaglia, Giuseppe; Palma, Antonio; Gentil, Paulo; Neri, Marco; Paoli, Antonio (2016). “Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males”. Journal of Translational Medicine. 14 (1): 290. doi:10.1186/s12967-016-1044-0. PMC 5064803 . PMID 27737674. 
  • ^ Stote, KS; Baer, DJ; Spears, K; Paul, DR; Harris, GK; Rumpler, WV; Strycula, P; Najjar, SS; Ferrucci, L; Ingram, D. K.; Longo, D. L.; Mattson, M. P. (2007). “A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults” (PDF). The American Journal of Clinical Nutrition. 85 (4): 981–8. PMC 2645638 . PMID 17413096. 
  • ^ “How to diet”. Live Well – NHS Choices. UK National Health Service. 9 December 2011. Retrieved 10 February 2014. 
  • ^ Trueland, Jennifer (2013). “Fast and effective?”. Nursing Standard. 28 (16): 26–7. doi:10.7748/ns2013. PMID 24345130. 
  • ^ Healy A (11 June 2013). “Dietitians warn against fad diets”. Irish Times. 
  • ^ Mosley, Michael (5 September 2012). “Eat, Fast & Live Longer”. Horizon. Episode 49×03. BBC. 2. Retrieved 10 February 2014. 
  • ^ “The UK’s Hot New 5:2 Diet Craze Hits The U.S. – Weight Loss Miracle?”. Forbes. 17 May 2013. Retrieved 10 February 2014. 
  • ^ “News analysis: Does the 5:2 intermittent fasting diet work?”. Health News. UK National Health Service – NHS Choices. May 2013. Retrieved 23 November 2016. 
  • ^ “Could 5:2 diet play a role in preventing breast cancer?”. NHS Choices. 17 June 2016. 
  • ^ Collier, R (2013). “Intermittent fasting: The science of going without”. Canadian Medical Association Journal. 185 (9): E363–4. doi:10.1503/cmaj.109-4451. PMC 3680567 . PMID 23569168. 
  • ^ a b c Longo, Valter D; Mattson, Mark P (2014). “Fasting: Molecular Mechanisms and Clinical Applications”. Cell Metabolism. 19 (2): 181–92. doi:10.1016/j.cmet.2013.12.008. PMC 3946160 . PMID 24440038. 
  • ^ Barnosky, Adrienne R; Hoddy, Kristin K; Unterman, Terry G; Varady, Krista A (2014). “Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: A review of human findings”. Translational Research. 164 (4): 302–11. doi:10.1016/j.trsl.2014.05.013. PMID 24993615. 
  • ^ a b Anton, Stephen D; Moehl, Keelin; Donahoo, William T; Marosi, Krisztina; Lee, Stephanie A; Mainous, Arch G; Leeuwenburgh, Christiaan; Mattson, Mark P (2017). “Flipping the Metabolic Switch: Understanding and Applying the Health Benefits of Fasting”. Obesity. doi:10.1002/oby.22065. PMID 29086496. 
  • ^ Mattson, Mark P.; Allison, David B.; Fontana, Luigi; Harvie, Michelle; Longo, Valter D.; Malaisse, Willy J.; Mosley, Michael; Notterpek, Lucia; Ravussin, Eric (2014-11-25). “Meal frequency and timing in health and disease”. Proceedings of the National Academy of Sciences of the United States of America. 111 (47): 16647–16653. doi:10.1073/pnas.1413965111. PMC 4250148 . PMID 25404320. 
  • ^ Horne, Benjamin D; Muhlestein, Joseph B; Anderson, Jeffrey L (2015-08-01). “Health effects of intermittent fasting: hormesis or harm? A systematic review”. The American Journal of Clinical Nutrition. 102 (2): 464–470. doi:10.3945/ajcn.115.109553. ISSN 0002-9165. 

  • Source: https://en.wikipedia.org/wiki/Intermittent_fasting

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