* Corresponding author: Kiarash Ghazvini, Antimicrobial Resistance Research Center, Buali Research Institute, Department of Microbiology and Virology, Mashhad University of Medical Sciences, Mashhad, Iran. Tel: +98 51 38012589; +98 915 1248938; Fax: +98 51 38409612; Email: Ghazvinik@mums.ac.ir © 2014 mums.ac.ir All rights reserved.    This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

 

ImpactofShort‐term,RepeatedWaterFastingon theWeightofMiceZahraMishmast1,RezaRahimzadehOskuee2,AmiraliAryan1,KamranGhafarzadegan3,KiarashGhazvini1*1. AntimicrobialResistanceResearchCenter,AvicennaResearchInstitute,DepartmentofMicrobiologyandVirology,FacultyofMedicine,Mashhad

UniversityofMedicalSciences,Mashhad,Iran2. Neurology and Neurosurgery Research Group, Students Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences,

Mashhad,Iran3. DepartmentofPathology,MashhadUniversityofMedicalSciences,Mashhad,Iran

ARTICLEINFO ABSTRACT

Articletype:Originalarticle

Introduction: Caloric restriction is a strategy applied forweight loss.Water fasting is apopular way for obesity treatment. However, little is known about the impact of waterfastingonweight.Therefore, this studywasconducted to investigate theeffectof short‐term,repeatedwaterfastingontheweightofmice. Method:Inthisstudy,thephysiologicaleffectofshort‐term,repeatedwaterfastingontheweightoffemalemicewasevaluated.At6weeksofage,micewererandomlyassignedtoeitherrepeated‐fastingorcontrolgroup(fedad libitum).Eachgroupconsistedoftwentymice.As the fastingperiodstarted, the repeated‐fastinggrouphadaccess toonlywater;animalshadfreeaccesstofoodandwateronnon‐fastingdays.Bodyweightofeachgroupbefore,during,andafterthefastingperiodwasrecorded.Results:Bodyweightofthefastinggroupsignificantlydecreased,unlikethecontrolgroup.However, the fasting group gained weight rapidly after being re‐fed and becamesignificantly heavier thanmice in the control group (P<0.01). Interestingly, the averagebodyweightofthefastinggroupincreased,comparedtothatofthecontrolgroup;infact,thefastingmiceweighedapproximately10%heavierthanthecontrolones.Conclusion: Repeated water fasting was not only ineffective for weight loss but alsoincreasedthebodyweightoffastingmice.

ArticleHistory:Received:2Aug2014Revised:20Aug2014Accepted:21Aug2014Published:7Sep2014

Keywords:MiceWaterfastingWeight

Pleasecitethispaperas:MishmastZ,RahimzadehOskueeR,AryanA,GhafarzadeganK,GhazviniK.ImpactofShort‐term,RepeatedWaterFastingontheWeightofMice.JFastingHealth.2014;2(2):76‐79.

IntroductionFasting and caloric restriction are traditional

strategiesfortreatingpatientswithobesity(1‐3).Inmanycultures,fastinghasbeenacceptedasanalternative method for treating psychosomaticdisorders(4).

Fasting has been shown to have manypositive effects on animals and humans.Moreover, themean andmaximum of rats’ lifeexpectancy have been reported to increase viacaloric restriction. Fasting can also decreasecomplications resulting from aging in rats (5‐12). Moreover, Sogava et al. reported thebeneficialeffectsof fastingon treatingallergiesandgastroentericdiseases(13).

Water fasting is a special type of fasting inwhich consuming foods is prohibited and thepractitionercanonlydrinkwater.Waterfasting

is more common in Asian countries. Recentstudies have also demonstrated the beneficialeffectsofwaterfastingonanimalsandhumans.

Increasing acceptance of complementarymedicine has resulted in the application oftherapeuticwater fasting for various purposes.However, scientific evidence in this field is notsufficient and effects of water fasting haveremainedunknown(14‐17).Therefore, theaimof this study was to clarify the relationshipbetween water fasting and weight loss duringfastingperiods.

MaterialsandMethodMice

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Mishmast Z et al Influence of Water-Fasting on the Weight

 

78 J Fasting Health. 2014; 2(2):76-79.    

 

DiscussionInthecurrentstudy,weevaluatedtheimpact

of short‐term, repeated water fasting on theweight of female mice. According to ourfindings, water fasting could cause weight lossonly during the first period and was noteffective in sustainableweight loss (although itpreventedweightchanges).

When body does not have access to foodsupplies, itdoesnot immediatelyrelyonbodyfatstores forenergysince thereare still someshort‐livedenergysourcessuchasbloodsugar,energy from consumed foods in the digestivesystem, andmuscle and liver glycogen stores.Therefore, itusuallytakessomehoursordaysbefore the short‐lived energy stores are allemptiedout.Beyondthatpoint,body is forcedto switch almost exclusively to burning bodyfatsforsurvival;thisiswheretrueweightlossstartshappening(18).

In addition to possible weight loss, waterfastingwith caloric restriction has been showntohavesomepositiveeffectsonlifeexpectancyand chronic diseases, e.g., cardiovasculardiseases, hypertension, and type 2 diabetes.Fastinghasalsobeenshowntodecreasecancerrate by reducing cell proliferation (19). In thisregard, many trial studies have suggested thatmedicallysupervisedwaterfastingisasafeandeffective means of moderating metabolic andchronic disorders and may assist healthpromotion(20).

As other animal studies have indicated,fastingmight enhance survival rate and alterbiochemical factors associated with lifeexpectancy (21). Valter Longo showed thatfasting has a positive impact on insulin‐likegrowth factor‐1 (IGF‐1) expression, whichaffects the aging process. According to theaforementioned research,when an individualconsumes food, IGF‐1 drives cells toreproduce and intrigues the aging process.Therefore, intermittent fastingdecreases IGF‐1 expression and switches on other DNArepair genes. In thisway, intermittent fastingswitches the body from “growth mode” to“repairmode”(22).

Manyotherin‐vitroandin‐vivostudieshavedemonstrated the beneficial or adverse effectsof fasting on various types of disordersincluding obesity, diabetes mellitus, andhypertension(23,24).

Controversially, inour study,weobservedweight gain of rats over a long‐term period.Therefore, it can be concluded that manyother factors may influence body weight,apart from the amount of food consumption.For instance, in one study by SatchidanandaPandaetal.,miceweregivenahigh‐fat,high‐calorie diet, which was changed when theywere allowed to eat. Despite consuming thesame amount of calories,micewith access tofood for only eight hours at night (the mostactiveperiodformice)remainedleananddidnotdevelopanyhealthproblems.Ontheotherhand, the all‐day access group became obeseand was afflicted with health problemsincluding high cholesterol, high blood sugar,fatty liver disease, and metabolic problems(18,25).

The findings of the mentioned studysuggestthatbodymaybenefit fromthebreakit receives while fasting, whereas constanteatingmay lead to metabolic exhaustion andhealthconsequencessuchasweightgain.Thelatest studies by researchers show that it ispossible to avoid metabolic diseases byperiodic fasting or adhering to regular mealschedules rather than eating small meals offandonallday(18).

Ontheotherhand,somestudiesshowedthatwaterandfoodfastingmayincreasehematocrit,serum protein, and albumin levels, which canlead to increased viscosity. These fasting‐induced changes could deprive vital organs ofblood supplies in patients with venousinsufficiency (26). In another study, waterfasting resulted in reduced heart rate andcapacity of physical activity at rest (27).However, several effects of fasting on lipid oradiposeformationarestillunclear.

ConclusionStrict caloric restriction such as water

fasting could cause weight loss only in thebeginning. More interestingly, repeated waterfastingwasnotonlyineffectiveforweight lossbut also led to weight gain in fasting mice.Nevertheless, short‐term, repeated fastingcouldpreventweight changesandbalance theweight of mice. Further human studies withlarge populations should be performed inorder to demonstrate the possible impact ofwaterfastingonobesity.

Influence of Water-Fasting on the Weight Mishmast Z et al

 

J Fasting Health. 2014; 2(2):76-79.     79    

 

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