Intermittent fasting

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Intermittent fasting (IF) describes diets that cycle between a period of fasting and non-fasting. In some contexts, fasting allows the consumption of a limited amount of low-calorie beverages such as coffee or tea.[1]

Intermittent fasting and caloric restriction are forms of dietary restriction (DR), which is sometimes referred to as dietary energy restriction (DER). 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).[citation needed] Some studies suggest that benefits could be the result of an overall reduction in caloric intake.[2][3]

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


One form of intermittent fasting, alternate day fasting (ADF), involves a 24-hour fast followed by a 24-hour non-fasting period. This is sometimes referred to as every other day fasting or every other day feeding. Alternate-day calorie restriction may prolong life span.[5][unreliable source?]

Modified fasting involves limiting caloric intake(e.g., 20% of normal) on fasting days rather than none at all. A study suggests that this regimen may retain most of the benefits of intermittent fasting.[5][unreliable source?]

Another form involves eating only one meal per day. In cases that do not restrain consumption, overall calorie intake may increase which worsens some cardiovascular disease risk factors.[6]

More generally, forms may choose to specify various ratios of fasting to non-fasting periods. The BBC2 Horizon documentary Eat, Fast and Live Longer [7] covered people who committed to fasting two non-consecutive days per week. Known as the 5:2 diet, people consumed 400–500 calories (women) or 500–600 calories (men) during the days of fasting. During feed days, the diet was regular.[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:

See also[edit]


  1. ^ "An Introduction to Intermittent Fasting". Retrieved 2012-11-26. 
  2. ^ Anson, R. Michael; Guo, Zhihong; de Cabo, Rafael; Iyun, Titilola; Rios, Michelle; Hagepanos, Adrienne; Ingram, Donald K.; Lane, Mark A.; Mattson, Mark P. (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. 
  3. ^ 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. 
  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. ^ 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. 
  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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