Intermittent fasting

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Intermittent fasting (IF) is a pattern of eating that alternates between periods of fasting (usually meaning consumption of water and sometimes low-calorie drinks such as black coffee) and non-fasting.

There is evidence suggesting that intermittent fasting may have beneficial effects on the health and longevity of animals—including humans—that are similar to the effects of caloric restriction (CR). There is currently no consensus as to the degree to which this is simply due to fasting or due to an (often) concomitant overall decrease in calories, but recent studies have shown support for the former.[1][2] Alternate-day calorie restriction may prolong life span.[3] Intermittent fasting and caloric restriction are forms of dietary restriction (DR), which is sometimes referred to as dietary energy restriction (DER).

Scientific study of intermittent fasting in rats (and anecdotally in humans) has been conducted at least as far back as 1943.[4]

A specific form of intermittent fasting is alternate day fasting (ADF), also referred to as every other day fasting (EOD), or every other day feeding (EODF), a 48-hour routine typically composed of a 24-hour fast followed by a 24-hour non-fasting period.

Types of diet[edit]

In common usage, intermittent fasting describes any diet that includes a period of fasting and a period of non-fasting, even if the diet involves consuming a limited amount of calorie-containing beverages such as coffee or tea during the fasting period.[5]

Another variation on intermittent fasting is to consume limited calories (e.g., 20% of normal) rather than none at all on fasting days – so-called 'modified fasting'. This regimen may provide many of the benefits of intermittent fasting while being much more acceptable and likely to be adhered to.[3]

Another possibility is eating only one meal per day without caloric restriction. When overall calorie intake is not reduced, this diet worsens some cardiovascular disease risk factors.[6]

The BBC2 Horizon documentary Eat, Fast and Live Longer [7] showed another plan: during days of fasting, people eat 400–500 calories (women) or 500–600 calories (men), and during feed days, the diet was unrestricted. This was done either alternately (one day fasting, one day feeding) or by fasting two days per week: the 5:2 diet.[8]


Animal health[edit]

A 2007 review of alternate day fasting in said "the findings in animals suggest that ADF may effectively modulate several risk factors, thereby preventing chronic disease, and that ADF may modulate disease risk to an extent similar to that of CR. More research is required to establish definitively the consequences of ADF."[9]

Human health[edit]

Studies on humans suggest possible benefits:


  1. ^ Anson, R. Michael; Guo, Zhihong; de Cabo, Rafael; Iyun, Titilola; Rios, Michelle; Hagepanos, Adrienne; Ingram, Donald K.; Lane, Mark A. et al. (2003). "Intermittent fasting dissociates beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from calorie intake". Proceedings of the National Academy of Sciences 100 (10): 6216–20. Bibcode:2003PNAS..100.6216A. doi:10.1073/pnas.1035720100. JSTOR 3147568. PMC 156352. PMID 12724520. 
  2. ^ Wan, R; Camandola, S; Mattson, MP (2003). "Intermittent food deprivation improves cardiovascular and neuroendocrine responses to stress in rats". The Journal of nutrition 133 (6): 1921–9. PMID 12771340. 
  3. ^ a b Johnson, James B.; Laub, Donald R.; John, Sujit (2006). "The effect on health of alternate day calorie restriction: Eating less and more than needed on alternate days prolongs life". Medical Hypotheses 67 (2): 209–11. doi:10.1016/j.mehy.2006.01.030. PMID 16529878. 
  4. ^ Carlson, AJ; Hoelzel, F (1946). "Apparent prolongation of the life span of rats by intermittent fasting". The Journal of nutrition 31: 363–75. PMID 21021020. 
  5. ^ "An Introduction to Intermittent Fasting". Retrieved 2012-11-26. 
  6. ^ Stote, KS; Baer, DJ; Spears, K; Paul, DR; Harris, GK; Rumpler, WV; Strycula, P; Najjar, SS et al. (2007). "A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults". The American journal of clinical nutrition 85 (4): 981–8. PMC 2645638. PMID 17413096. 
  7. ^ Mosley, Michael. "Eat, Fast and Live Longer". BBC. Retrieved 27 October 2013. 
  8. ^ "Eat, Fast and Live Longer with Michael Mosley". PBS. 3 April 2013. 
  9. ^ Varady, KA; Hellerstein, MK (2007). "Alternate-day fasting and chronic disease prevention: A review of human and animal trials". The American journal of clinical nutrition 86 (1): 7–13. PMID 17616757. 
  10. ^ Mattson, Mark P. (2008). "Dietary factors, hormesis and health". Ageing Research Reviews 7 (1): 43–8. doi:10.1016/j.arr.2007.08.004. PMC 2253665. PMID 17913594. 
  11. ^ Heilbronn, Leonie K; Smith, Steven R; Martin, Corby K; Anton, Stephen D; Ravussin, Eric (2005). "Alternate-day fasting in nonobese subjects: Effects on body weight, body composition, and energy metabolism". The American Journal of Clinical Nutrition 81 (1): 69–73. PMID 15640462. 
  12. ^ Klempel, Monica C.; Kroeger, Cynthia M.; Varady, Krista A. (2013). "Alternate day fasting (ADF) with a high-fat diet produces similar weight loss and cardio-protection as ADF with a low-fat diet". Metabolism 62 (1): 137–43. doi:10.1016/j.metabol.2012.07.002. PMID 22889512. 

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