Intermittent fasting has become one of the most popular health and fitness trends because so many of us have lost sight of not only what to eat but when to eat it!
Intermittent fasting is not a weight loss diet although it may help people lose weight. It is instead an eating pattern that alternates between periods of food abstinence and eating.
Intermittent fasting focuses on when foods are eaten not on WHAT foods are eaten although that should be part of the plan. Its health benefits are maximized if combined with a superior, grain-free diet of fresh, whole vegetables, fish, and poultry that avoids sugar and alcohol.
Evolutionary adaptation to seasonal periods of food scarcity left us able to function without food for extended periods of time. Indeed, intermittent fasting is more natural than eating 3 or more times per day.
Intermittent fasting methodologies split the day or week into eating and fasting periods. Participants should eat nothing at all while fasting although some programs may allow eating 20% to 40% of normal consumption. Minimal calorie “fasts” may be necessary for neophytes experiencing difficulty adjusting to intermittent fasts. Replacing food with a few glasses a day of Vibrant Health’s Vibrant Cleanse with or without Green Vibrance added to water will provide ample micronutrition from minimal calories. The benefits of intermittent fasting may even be enhanced.
The common methods:
· The 16/8 method restricts the daily eating period to 8 hours. The best schedule allows eating from 10:00 a.m. to 6:00 p.m. and fasting from 6:00 p.m. to 10:00 a.m. This reduces stress on the digestive tract and is associated with healthful weight and appetite control.
· Alternate Day Fasting: Fast for 24 hours, once or twice a week.
· The 5:2 diet permits eating only 500–600 calories on two non-consecutive days of the week while eating normally the other 5 days.
All intermittent fasting (IF) methods should reduce one’s calorie intake. They may also improve chances to live a long life. Animal studies confirm that calorie restriction extends lifespan. This benefit is possible as long as the faster does not overcompensate for the periods of abstinence by eating too much food when it is again allowed.
Cellular and hormonal effects
1.) Hormone levels adjust to release stored body fat for metabolism.
2.) Cells initiate important repair processes.
3.) The expression of certain genes is changed.
These effects of IF lead to observed health benefits:
Human Growth Hormone (HGH) increases in blood serum during fasting. Significant elevations are seen over the first full day of fasting until a 5-fold increase occurs by the end of day two. [i]
Higher levels of HGH aid fat loss and increase lean muscle mass. [ii] But restorative boosts to HGH do not appear in shorter 16-hour fasts. A full one – or two-day fast is required.
Insulin levels in the blood drop under all types of fasting, whether of one or more full day’s duration, of 16-hours, or in a simple calorie-restricted pseudo-fast where only 25% of a normal day’s calories are consumed. [iii][iv] Lower fasting insulin levels are biomarkers in favor of longevity and make stored body fat more accessible, contributing to body fat loss.
Cellular repair processes are initiated and accelerated throughout the body by fasting as cells are liberated from the obligation to metabolize incoming nutrients and biochemicals. The process may promote therapeutic autophagy in neurological tissue, including the brain. [v][vi]
Gene expression changes function to improve longevity and protect against disease. Fasting of all sorts affects many biochemical pathways related to cellular growth, metabolism, protection against oxidative stress, and aging. The alterations are positive and appear to be related to the genetic expression of Sirtuin enzymes, [vii][viii] reducing the risks of diabetes, cardiovascular disease, cancer and any disorder characterized by inflammation. IF can reduce DNA damage, reducing the risk of mutagenesis and carcinogenesis. [ix]
IF should reduce calorie intake but may bring on hunger, possibly discouraging someone from trying to restrict food intake and lose weight. [x] Eating nutrient-dense fresh whole foods and meats rather than processed foods during eating cycles can mitigate hunger.
IF’s advantage over simple calorie restriction diets results in part by fasting’s ability to elevate HGH, which can maintain lean muscle mass while calorie restriction customarily leads to a reduction in BOTH fat tissue and lean tissue. [xi]
Fasting increases the release of the fat-burning hormone, norepinephrine. But it is true fasting – not intermittent or alternate-day fasting – that raises norepinephrine and speeds up the metabolic rate. Expected increases to the metabolic rate are 3.6% after a 48 hour fast [xii] and 14.1% over a prolonged fast of 84 hours in response to increased plasma norepinephrine. [xiii]
Intermittent fasting (IF) and alternate-day fasting (ADF) do not drive up norepinephrine levels. [xiv] IF eating patterns can nevertheless cause a 3% to 8% weight loss over 3 to 24 weeks with a significant loss of dangerous visceral belly fat [xv] that is known to contribute to diabetes, cardiovascular disease, and shortened lifespan.
Health Benefitsof IF and ADF
· Stimulates weight loss and loss of belly fat.
· Lowers insulin and cellular stress and may help extend lifespan.
· Reduces insulin resistance possibly lowering blood sugar by 3% to 6% and fasting insulin levels by 20–31%, helping protect against type 2 diabetes. [xvi]
· May reduce Asthma symptoms, improve pulmonary function, reduce oxidative stress and inflammation in overweight adults with moderate asthma. [xix]
· Supports heart health by reducing “bad” LDL cholesterol, blood triglycerides, inflammation, blood sugar, fasting insulin, and insulin resistance risk factors for heart disease, high blood pressure, and obesity. [xx][xxi]
· Supports brain health by improving energy production, oxygen radical metabolism, and cellular stress responses in ways that protect brain cells against genetic and environmental stressors during aging. [xxv] IF can suppress age-related deficits in learning and memory and can increase the resistance of neurons to degeneration, helping keep brain function healthy [xxvi] and may also protect against Alzheimer’s disease. [xxvii]
· Resists-aging through biochemical adjustments similar to those seen in rats and mice, indicating that humans may rightly expect similar improvements to lifespan …if one can remain disciplined enough to follow an intermittent fasting lifestyle. [xxviii][xxix][xxx][xxxi][xxxii]
Putting it all together
Adaptive cellular responses in fasting:
· reduces oxidative damage and inflammation,
· optimizes energy metabolism,
· and bolsters cellular protection.
Chronic fasting extends longevity and protects against diabetes, cancers, heart disease and neurodegeneration in lower species. In humans, it helps reduce obesity, hypertension, asthma, and rheumatoid arthritis while reducing the risk of cardiovascular disease and cancer. Fasting has the potential to delay aging and to help prevent and (adjunctively) treat diseases. [xxxiii]
Intermittent fasting protocols are not suitable for:
Children, pregnant or lactating women, or those planning to become pregnant. It may adversely affect glucose tolerance in nonobese women but not in nonobese men.[xxxiv] Some women may experience amenorrhea. In such cases, abandon IF protocols and resume previous eating patterns.
As with any major lifestyle change, people with serious medical conditions should consult with their physician – if knowledgeable about fasting – and/or with other competent health professionals before adopting an intermittent fasting regimen.
[i]Hartman ML1, Veldhuis JD, Johnson ML, Lee MM, Alberti KG, Samojlik E, Thorner MO., Augmented growth hormone (GH) secretory burst frequency and amplitude mediate enhanced GH secretion during a two-day fast in normal men.J Clin Endocrinol Metab. 1992 Apr;74(4):757-65.
[ii]Rudman D, Feller AG, Nagraj HS, Gergans GA, Lalitha PY, Goldberg AF, Schlenker RA, Cohn L, Rudman IW, Mattson DE. Effects of human growth hormone in men over 60 years old. N Engl J Med. 1990 Jul 5;323(1):1-6.
[iii]Hoddy KK, Gibbons C, Kroeger CM, Trepanowski JF, Barnosky A, Bhutani S, Gabel K, Finlayson G, Varady KA. Changes in hunger and fullness in relation to gut peptides before and after 8 weeks of alternate day fasting.Clin Nutr. 2016 Dec;35(6):1380-1385.
[iv]Heilbronn LK, de Jonge L, Frisard MI, DeLany JP, Larson-Meyer DE, Rood J, Nguyen T, Martin CK, Volaufova J, Most MM, Greenway FL, Smith SR, Deutsch WA, Williamson DA, Ravussin E., Effect of 6-month calorie restriction on biomarkers of longevity, metabolic adaptation, and oxidative stress in overweight individuals: a randomized controlled trial. JAMA. 2006 Jun 7;295(21):2482.
[v]Mehrdad Alirezaei, Christopher C. Kemball, Claudia T. Flynn, Malcolm R. Wood, J. Lindsay Whitton, and William B. Kiosses, Short-term fasting induces profound neuronal autophagy, Autophagy. 2010 Aug 16; 6(6): 702–710.
[vi]Kim I, Lemasters JJ. Mitochondrial degradation by autophagy (mitophagy) in GFP-LC3 transgenic hepatocytes during nutrient deprivation.Am J Physiol Cell Physiol. 2011 Feb;300(2):C308-17.
[vii]Koubova J, Guarente L. How does calorie restriction work?Genes Dev. 2003;17:313–321.
[viii]Haigis MC, Guarente LP. Mammalian sirtuins–emerging roles in physiology, aging, and calorie restriction.Genes Dev. 2006;20:2913–2921.
[ix]Op. cit., Heilbronn LK, et.al.
[x]Johnstone A. Fasting for weight loss: an effective strategy or latest dieting trend?Int J Obes (Lond). 2015 May;39(5):727-33.
[xi]Varady KA. Intermittent versus daily calorie restriction: which diet regimen is more effective for weight loss?Obes Rev. 2011 Jul;12(7):e593-601.
[xii]Mansell PI, Fellows IW, Macdonald IA. Enhanced thermogenic response to epinephrine after 48-h starvation in humans.Am J Physiol. 1990 Jan;258(1 Pt 2):R87-93.
[xiii]Zauner C, Schneeweiss B, Kranz A, Madl C, Ratheiser K, Kramer L, Roth E, Schneider B, Lenz K. Resting energy expenditure in short-term starvation is increased as a result of an increase in serum norepinephrine. Am J Clin Nutr. 2000 Jun;71(6):1511-5.
[xiv]Heilbronn LK, Smith SR, Martin CK, Anton SD, Ravussin E. Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism.Am J Clin Nutr. 2005 Jan;81(1):69-73.
[xv]Op. cit., Adrienne R.Barnosky, et. al.
[xvi]Ibid., Adrienne R.Barnosky, et. al.
[xvii]Aksungar FB, Topkaya AE, Akyildiz M. Interleukin-6, C-reactive protein and biochemical parameters during prolonged intermittent fasting.Ann Nutr Metab. 2007;51(1):88-95.
[xviii]Faris MA, Kacimi S, Al-Kurd RA, Fararjeh MA, Bustanji YK, Mohammad MK, Salem ML. Intermittent fasting during Ramadan attenuates proinflammatory cytokines and immune cells in healthy subjects. Nutr Res. 2012 Dec;32(12):947-55.
[xix]Johnson JB, Summer W, Cutler RG, Martin B, Hyun DH, Dixit VD, Pearson M, Nassar M, Telljohann R, Maudsley S, Carlson O, John S, Laub DR, Mattson MP. Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma. Free Radic Biol Med. 2007 Mar 1;42(5):665-74.
[xx]Varady KA, Bhutani S, Church EC, Klempel MC. Short-term modified alternate-day fasting: a novel dietary strategy for weight loss and cardioprotection in obese adults. Am J Clin Nutr. 2009 Nov;90(5):1138-43.
[xxi][xxi]Op. cit., Adrienne R.Barnosky, et. al.
[xxii]Siegel I, Liu TL, Nepomuceno N, Gleicher N. Effects of short-term dietary restriction on survival of mammary ascites tumor-bearing rats.Cancer Invest. 1988;6(6):677-80.
[xxiii]Rocha NS, Barbisan LF, de Oliveira ML, de Camargo JL. Effects of fasting and intermittent fasting on rat hepatocarcinogenesis induced by diethylnitrosamine.Teratog Carcinog Mutagen. 2002;22(2):129-38.
[xxiv]Lee C, Raffaghello L, Brandhorst S, Safdie FM, Bianchi G, Martin-Montalvo A, Pistoia V, Wei M, Hwang S, Merlino A, Emionite L, de Cabo R, Longo VD. Fasting cycles retard growth of tumors and sensitize a range of cancer cell types to chemotherapy.Sci Transl Med. 2012 Mar 7;4(124):124ra27.
[xxv]Bronwen Martin, Mark P. Mattson, and Stuart Maudsley, Caloric restriction and intermittent fasting: Two potential diets for successful brain aging,Ageing Res Rev. 2006 Aug; 5(3): 332–353.
[xxvi]Lee J, Duan W, Long JM, Ingram DK, Mattson MP. Dietary restriction increases the number of newly generated neural cells, and induces BDNF expression, in the dentate gyrus of rats.J Mol Neurosci. 2000 Oct;15(2):99-108.
[xxvii]Halagappa VK, Guo Z, Pearson M, Matsuoka Y, Cutler RG, Laferla FM, Mattson MP. Intermittent fasting and caloric restriction ameliorate age-related behavioral deficits in the triple-transgenic mouse model of Alzheimer’s disease.Neurobiol Dis. 2007 Apr;26(1):212-20.
[xxviii]R. Weindruch, R.L. Walford, The Retardation of Aging and Disease by Dietary Restriction, C.C. Thomas, Springfield, Ill., U.S.A. (1988)
[xxix]L. Fontana, S. Klein, Aging, adiposity, and calorie restriction. JAMA, 297 (2007), pp. 986-994
[xxx]L. Fontana, L. Partridge, V.D. Longo, Extending healthy life span—from yeast to humans, Science, 328 (2010), pp. 321-326
[xxxi]E.J. Masoro, Overview of caloric restriction and ageing, Mech. Ageing Dev., 126 (2005), pp. 913-922
[xxxii]HiroshiSogawa, ChiharuKubo, Influence of short-term repeated fasting on the longevity of female (NZB×NZW)F1 mice,Mechanisms of Ageing and Development, Volume 115, Issues 1–2, 17 May 2000, Pages 61-71
[xxxiii]Valter D. Longo1 and Mark P. Mattson, Fasting: Molecular Mechanisms and Clinical Applications, Cell Metab. 2014 Feb 4; 19(2): 181–192.
[xxxiv]Heilbronn LK, Civitarese AE, Bogacka I, Smith SR, Hulver M, Ravussin E. Glucose tolerance and skeletal muscle gene expression in response to alternate day fasting. Obes Res. 2005 Mar;13(3):574-81.