Improvementincoronaryheartdiseaserisk factorsduringanintermittentfastingcalorie restrictionregimenRelationshipto adipokinemodulations CynthiaMKroeger 1 MonicaCKlempel 1 SurabhiBhutani 1 JohnFTrep ID: 299383
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RESEARCHOpenAccess Improvementincoronaryheartdiseaserisk factorsduringanintermittentfasting/calorie restrictionregimen:Relationshipto adipokinemodulations CynthiaMKroeger 1 ,MonicaCKlempel 1 ,SurabhiBhutani 1 ,JohnFTrepanowski 1 ,ChristineCTangney 2 andKristaAVarady 1* Abstract Background: Theabilityofanintermittentfasting(IF)-calorierestriction(CR)regimen(withorwithoutliquidmeals) tomodulateadipokinesinawaythatisprotectiveagainstcoronaryheartdisease(CHD)hasyettobetested. Objective: Accordingly,weexaminedtheeffectsofanIFCRdietonadipokineprofile,bodycomposition,and markersofCHDriskinobesewomen. Methods: Subjects(n=54)wererandomizedtoeithertheIFCR-liquid(IFCR-L)orIFCR-foodbased(IFCR-F)dietfor 10weeks. Results: Greaterdecreasesinbodyweightandwaistcircumfe rencewerenotedintheIFCR-Lgroup(4±1kg;6±1cm) versustheIFCR-Fgroup(3±1kg;4±1cm).Similarreductions(P0.0001)infatmassweredemonstratedinthe IFCR-L(3±1kg)andIFCR-Fgroup(2±1kg).ReductionsintotalandLDLcholesterollevelsweregreater(P=0.04) intheIFCR-L(19±10%;20±9%,respectively)versustheIFCR-Fgroup(8±3%;7±4%,respectively).LDLpeak particlesizeincreased(P0.01)intheIFCR-Lgrouponly.TheproportionofsmallLDLparticlesdecreased(P0.01) inbothgroups.Adipokines,suchasleptin,interleukin-6(IL-6),tumornecrosisfactor-alpha(TNF-alpha),and insulin-likegrowthfactor-1(IGF-1)decreased(P0.05),intheIFCR-Lgrouponly. Conclusion: ThesefindingssuggestthatIFCRwithaliquiddietfavorablymodulatesvisceralfatandadipokinesina waythatmayconferprotectionagainstCHD. Keywords: disease,Obesewomen Introduction Intermittentfasting(IF)isanovelweightlossregimen thathasbeensteadilygrowinginpopularityoverthe pastdecade[1].Thisdietstrategygenerallyinvolvesse- vererestriction(75-90%ofenergyneeds)on1 2days perweek.Thoughclinicaltrialevidenceisstilllimited [2,3],preliminaryfindingsindicatethatIFmaybeeffect- iveforweightlossandcoronaryheartdisease(CHD) riskreduction.Forinstance,tworecenttrialsofIF demonstratedecreasesinbodyweightof7-9%and reductionsinLDLcholesterolof10%after20 24weeks oftreatment[2,3].Whilethesedataareencouraging, thisdiettherapyislimitedinthatalongdurationof time,i.e.24weeks,isrequiredtoexperiencemodest reductionsinweight.Onepossiblewaytoboosttherate ofweightlosswouldbetocombineIFwithdailycalorie restriction(CR).Infollowingthisprotocol,theindivid- ualwouldfastonedayperweek,andthenundergomild CR,i.e.20%restrictionofenergyneeds,on6daysper week.Theincorporationofportion-controlledliquid mealsmayalsoenhanceweightlossasithelpsindivi- dualstostaywithintheconfinesoftheirprescribed *Correspondence: varady@uic.edu DepartmentofKinesiologyandNutrition,UniversityofIllinoisatChicago, Chicago,IL,USA Fulllistofauthorinformationisavailableattheendofthearticle ©2012Kroegeretal.;licenseeBioMedCentralLtd.ThisisanOpenAccessarticledistributedunderthetermsoftheCreative CommonsAttributionLicense(http://creativecommons.org/licenses/by/2.0),whichpermitsunrestricteduse,distribution,and reproductioninanymedium,providedtheoriginalworkisproperlycited. Kroeger etal.Nutrition&Metabolism 2012, 9 :98 http://www.nutritionandmetabolism.com/content/9/1/98 energygoals[4,5].TheeffectofIFcombinedwithCR(withorwithoutliquidmeals)onbodyweightandCHDriskhasyettobetested.Althoughthemechanismsremainunclear,thelipid-loweringactionsofdietaryrestrictionprotocolsmaybemediated,inpart,bymodulationsinadipokines,i.e.fat-cellderivedhormonesandcytokines[6].LeptinisanadipokinethatplaysaroleinCHDdevelopmentbyincreasingplateletaggregation[7],andstimulatingtheproliferationandmigrationofendothelialcells[8].Interleukin-6(IL-6)andtumornecrosisfactor-alpha(TNF-alpha)arepro-inflammatorymediatorsreleasedbyadiposetissuethatarestrongindependentpredic-torsofCHD[9].C-reactiveprotein(CRP)isproducedbyadiposetissueinresponsetoariseinIL-6[10].CRPmayplayaroleinatherogenesisbybindingtooxidizedLDLandpromotingfoamcellformation[11].Isoprostanesareanothergroupofcompoundsreleasedbyadiposetissue[12].Isoprostanesactasmarkersofoxidativestress,andhavebeenshowntoaccumulateinatheroscleroticlesionsofcarotidarteriesderivedfromCHDpatients[12].Insulin-likegrowthhormone-1(IGF-1),anotheradiposetissue-derivedprotein,mayplayaroleinthedevelopmentofCHDbystimulatingtheproliferationofvascularsmoothmusclecells[13].Circulatingconcentrationsofthesehormonesaredic-tatedbyregionalfatdistribution[14].Excessvisceraladiposity,asdeterminedbyanincreasedwaistcircum-ference,isrelatedtoanincreasedincidenceofdyslipi-demia[14].Viscerallyobesewomen(definedasawaistcircumference�88cm)havehighercirculatinglevelsofeachoftheabove-mentionedadipokines,relativetosubcutaneouslyobesewomen[15].TheabilityofIFCRtoreducevisceralfatmass,andinturn,improvecirculatingadipokineprofile,remainsunknown.Accordingly,theobjectiveofthepresentstudywastoexaminetheeffectofIFCRwithaliquid-dietorfoodbaseddietonbodyweightandlipidriskfactorsforCHDinobesewomen,andtoevaluatehowchangesinadipo-kinesarerelatedtothesemodulationsinvasculardiseaserisk.ObesewomenwererecruitedfromtheChicagoareabymeansofadvertisementsplacedonandaroundtheUniversityofIllinoiscampus.Seventy-sevenindividualsrespondedtotheadvertisements,and60weredeemedeligibletoparticipateafterthepreliminaryquestion-naire,bodymassindex(BMI)andwaistcircumferenceassessment.Keyinclusioncriteriawereasfollows:female,age3565y,BMIbetween30and39.9kg/m,waistcir-cumference�88cmweightstablefor3monthspriortothebeginningofthestudy,i.e.5kgweightlossorgain,non-diabetic,nohistoryofcardiovasculardisease,nohis-toryofcancer,sedentaryorlightlyactivefor3monthspriortothebeginningofthestudy,i.e.h/weekoflight-intensityexerciseat2.54.0metabolicequivalents(METS),non-smoker,andnottakingweightloss,lipid-lowering,orglucose-loweringmedications.Peri-menopausalwomenwereexcludedfromthestudy,andpostmenopausalwomen(definedasabsenceofmensesfor2y)wererequiredtomaintaintheircurrenthormonereplacementtherapyregimenforthedurationofthestudy.TheexperimentalprotocolwasapprovedbytheOfficefortheProtectionofResearchSubjectsattheUniversityofIllinois,Chicago,andallvolunteersgavewritteninformedconsenttoparticipateinthetrial.DietinterventionsSubjectswererandomizedbywayofastratifiedrandomsample,basedonBMIandage,intoeithertheIFCR-liquiddiet(IFCR-L)group(n=30)orIFCR-foodbaseddiet(IFCR-F)group(n=30).Arandomnumbertablewasusedtorandomizethesubjectsfromeachstrataintotheinterventiongroups.The10-weektrialconsistedoftwodietaryphases:1)a2-weekbaselineweightmainten-anceperiod,and2)an8-weekweightlossperiod.Baselineweightmaintenancediet(Week1Eachsubjectparticipatedina2-weekbaselineweightmaintenanceperiodbeforecommencingthe8-weekweightlossintervention(Figure1).Duringthisperiod,subjectswererequestedtocontinueeatingtheirusualdietandtomaintainastablebodyweight.Weightlossdiets(Week3Afterthebaselineperiod,subjectspartookineithertheIFCR-LorIFCR-Finterventionfor8weeks(Figure1).TheMifflinequationwasusedtomeasureenergyrequirements[16].IFCR-Lsubjects(n=30)consumedacalorie-restrictedliquiddietforthefirst6daysoftheweek,andthenunderwentafastonthelastdayoftheweek(waterconsumption+120kcalofjuicepowderonly,for24h).Theliquiddietconsistedofaliquidmealreplacementforbreakfast(240kcal)andaliquidmealreplacementforlunch(240kcal).Allliquidmealrepla-cementswereprovidedtothesubjectsinpowder-forminpremeasuredenvelopes(IsaleanShake,IsagenixLLC,Chandler,AZ).Forthedinnertimemeal,IFCR-Lsubjectsconsumeda400600kcalmeal.Foodwasnotprovidedtothesubjectsforthedinnermeal.Instead,subjectsmetwithaRegisteredDieticianweeklytolearnhowtomakehealthyeatingchoicesthatareincompliancewiththeNationalCholesterolEducationProgramTherapeuticLifestyleChanges(TLC)diet(i.e.ofkcalasfat;50-60%ofkcalascarbohydrates;mg/dofdietarycholesterol;and2030g/doffiber).Infollowingthisetal.Nutrition&MetabolismPage2of8http://www.nutritionandmetabolism.com/content/9/1/98 7dintervention,IFCR-Lsubjectswereenergyrestricted by30%oftheirbaselineneeds.IFCR-Fsubjects(n=30) consumedacalorie-restrictedfood-baseddietforthe first6daysoftheweek,andthenunderwentafastonthe lastdayoftheweek(waterconsumption+120kcalof juicepowderonly,for24h).IFCR-Fsubjectsate3meals perdayinaccordancewiththeTLCdietguidelines.Food wasnotprovidedtothesubjects.Instead,subjectsmet withaRegisteredDieticianweeklytolearnhowtomake healthyeatingchoicesbyimplementingtheTLCguide- lines.Subjectswereinstructedtoeatapproximately240 kcalforbreakfast,240kcalforlunch,and400 600kcal fordinner.Infollowingthis7dintervention,IFCR-F subjectswereenergyrestrictedby30%oftheirbaseline needs. Analyses Dietaryintakeandphysicalactivityassessment Amultiple-pass,telephone-administered,24-hrecallwas usedtoassessdietaryintake.Therecallswereperformed atweeks1,3and10byatrainedRegisteredDietician. DietaryintakedatawereanalyzedusingNutritionData System(NDS)software(version2012;UniversityofMin- nesota,Minneapolis,MN).Furthermore,IFCR-Lsubjects wereprovidedwithachecklisteachdaytomonitor:1) adherencetotheliquidmealprotocol,and2)adherence tothefastdayregimen.IFCR-Fsubjectswerealsogiven achecklisttomonitortheiradherencetothefastday regimen.Alterationsinenergyexpenditureassociated withchangesinphysicalactivityweremeasuredbythe useofapatternrecognitionmonitor(SenseWearMini (SWM),Bodymedia,Pittsburgh,PA).Subjectsworethe lightweightmonitorontheirupperarmfor7dat week3and10ofthetrial.Thedatawasanalyzed usingBodymediaSoftwareV.7.0,algorithmV.2.2.4 (Bodymedia,Pittsburgh,PA). Hunger,satisfaction,andfullnessassessment Subjectscompletedavalidatedvisualanalogscale(VAS) oneachfastdayapproximately5minbeforegoingto bed(reportedbedtimerangedfrom8.00pmto1.20am). Inbrief,theVASconsistedof100-mmlines,andsub- jectswereaskedtomakeaverticalmarkacrosstheline correspondingtotheirfeelingsfrom0(notatall)to100 (extremely)forhunger,satisfactionwithdiet,orfullness. TheVASwascollectedattheweigh-ineachweekand reviewedforcompleteness.Quantificationwasper- formedbymeasuringthedistancefromtheleftendof thelinetotheverticalmark. Bodyweightandbodycompositionassessment Bodyweightmeasurementsweretakentothenearest 0.5kgatthebeginningofeveryweekinlightclothing andwithoutshoesusingabalancebeamscale(Health- OMeter;SunbeamProducts,BocaRaton,FL).Height wasassessedusingawall-mountedstadiometertothe nearest0.1cm.BMIwasassessedaskg/m 2 .Fatmass andfatfreemasswereassessedbydualenergyX-ray absorptiometry(DXA)atweeks1,3and10(QDR 4500W,HologicInc.Arlington,MA).Waistcircum- ferencewasmeasuredbyaflexibletapetothenearest 0.1cm,midwaybetweenthelowercostalmarginand superiliaccrestduringaperiodofexpiration. Plasmalipidsandadipokineassessment Fastingbloodsampleswerecollectedbetween6.00am and9.00amatweeks1,3and10aftera12-hfast.Blood wascentrifugedfor10minat520×gat4°Ctoseparate plasmafromredbloodcellsandwasstoredat 80°C untilanalyzed.Plasmatotalcholesterol,directLDLchol- esterol,HDLcholesterol,andtriglycerideconcentrations weremeasuredinduplicatebyenzymatickits(Biovision Inc,Mountainview,CA).LDLparticlesizewasmeasured bylinearpolyacrylamidegelelectrophoresis(Quantime- trixLipoprintSystem,RedondoBeach,CA),aspreviously described[17].Leptin,IL-6,TNF-alpha,CRP,8-isopros- tane,andIGF-1wereassessedinduplicateatweek1,3, and10byELISA(R&DSystems,Minneapolis,MN). Statistics Resultsarepresentedasmean±SEM.Samplesizewas calculatedasn=30subjectspergroup,assuminga5% decreaseinbodyweightintheIFCR-Lgroup,witha powerof80%andan riskof5%.Anindependentsam- ples t -testwasusedtotestbaselinedifferencesbetween groups.Repeated-measuresANOVAwasperformed, takingtimeasthewithin-subjectfactoranddietasthe between-subjectfactor,toassessdifferencesbetween groupsoverthecourseofthestudy.Post-hocanalyses wereperformedusingtheTukeytest.Differenceswere Figure1 Experimentaldesign. Kroeger etal.Nutrition&Metabolism 2012, 9 :98 Page3of8 http://www.nutritionandmetabolism.com/content/9/1/98 consideredsignificantatP0.05.AlldatawasanalyzedusingSPSSsoftware(version20.0,SPSSInc,Chicago,IL).SubjectdropoutandbaselinecharacteristicsSixtysubjects(IFCR-Ln=30,IFCR-Fn=30)commencedthestudy.TwosubjectsdroppedoutoftheIFCR-Lgroupduetoschedulingconflicts(n=1)andproblemsadheringtothediet(n=1).FoursubjectsdroppedoutoftheIFCR-Fgroupbecauseofschedulingconflicts(n=2)andinabil-itytoadheretothedietprotocol(n=2).Thus,atotalof28and26subjectscompletedtheIFCR-LandIFCR-Finterventions,respectively.Therewerenodifferencesbe-tweengroupsforage,ethnicity,orBMI(Table1).DietaryintakeandphysicalactivityDietandphysicalactivitydataaredisplayedinTable2.Adherencetothefastdayprotocolwassimilarbetweengroups(P=0.91)(IFCR-l:96±4%compliance;IFCR-F:98±3%compliance).Compliancewiththeliquidmealprotocolwas92±3%intheIFCR-Lgroupoverthecourseofthe8weeks.Energyintakedecreased(P0.05)inboththeIFCR-LandIFCR-Fgroupsbetweenweek3and10.Therewerenochangesinfat,protein,carbohy-drate,cholesterol,orfiberintakefromthebeginningtotheendofthestudyineithergroup.Activityexpenditureandsteps/dremainedstableoverthecourseofthetrialinbothinterventiongroups.Hoursofsleeppernightalsodidnotchangeduringthe8-weekweightlossperiodineithertheIFCR-LorIFCR-Fgroup.Hunger,satisfaction,andfullnessassessmentHungerscoreswerelow,anddidnotdifferoverthecourseofthetrialintheIFCR-L(week3:27±8mm,week10:28±7mm)orIFCR-Fgroup(week3:46±7mm,week10:39±7mm).SatisfactionwiththedietsremainedelevatedfromthebeginningtotheendofthestudyintheIFCR-L(week3:72±7mm,week10:78±6mm)andIFCR-Fgroup(week3:55±9mm,week10:66±6mm).FullnessscoresweremoderateandstableduringthetrialintheIFCR-L(week3:66±7mm,week10:82±6mm)orIFCR-Fgroup(week3:58±7mm,week10:64±6mm).Nodifferenceswerenotedbe-tweengroupsforhunger,satisfactionorfullnessateithertimepoint.BodyweightandbodycompositionChangesinbodyweightandbodycompositionarereportedinTable3.BodyweightremainedstableinboththeIFCR-Lgroup(week1:95±3,week3:95±3kg)andIFCR-Fgroup(week1:94±3,week3:94±3kg)duringtheweightmaintenanceperiod.Bodyweightdecreasedtoagreaterextent(P0.05)intheIFCR-Lgroup(4±1kg)versustheIFCR-Fgroup(3±1kg)duringtheweightlossperiod.Similardecreases(P0.0001)infatmasswereobservedintheIFCR-L(3±1kg)andIFCR-F(2±1kg)groupsafter8weeksoftreatment.Fatfreemassremainedunchangedthroughoutthecourseofthetrialinbothgroups.Greaterdecreases(P0.05)inwaistcircumfer-enceweredemonstratedintheIFCR-L(6±1cm)whencomparedtotheIFCR-Fgroup(4±1cm).BMIdecreased(P0.0001)by1±1and1±1kg/m,respectively,intheIFCR-LandIFCR-Fgroups.PlasmalipidsandadipokinesChangesinplasmalipidconcentrationsandLDLparticlesizearedisplayedinFigure2.TotalandLDLcholesterolconcentrationswerereduced(P0.05)toagreaterextentintheIFCR-Lgroup(19±10%;20±9%,respect-ively)comparedtotheIFCR-Fgroup(8±3%;7±4%,respectively).HDLcholesterolwasnotchangedbyeitherdiet.Triglyceridesdecreased(P0.0001)intheIFCR-Lgrouponly(17±9%).LDLpeakparticlesizeincreased(P0.01)intheIFCR-Lgrouponly,whilethepropor-tionofsmallparticleswasreduced(P0.05)intheboththeIFCR-LandIFCR-Fgroups.ChangesinadipokinesarereportedinTable4.Leptindecreased(P0.05)toasimilarextentintheIFCR-L(9±2ng/ml)andtheIFCR-Fgroup(8±2ng/ml).IL-6,TNF-alpha,andIGF-1concentrationswerereduced(P0.05)intheIFCR-Lgrouponly.SignificantassociationsbetweenplasmalipidsandadiposetissueparameterswerenotedintheIFCR-Lgrouponly.Forinstance,decreasesinLDLcholesterolwererelatedtoreductionsinwaistcircum-ference(r=0.26,P=0.04),andleptin(r=0.37,P=0.04).Reductionsintriglycerideswerealsorelatedtodecreasedleptin(r=0.29,P=0.04)andTNF-alpha(r=0.33,P=0.03).Furthermore,decreasedwaistcir-cumferencewasrelatedtolowercirculatingleptinlevels(r=0.45,P=0.03). Table1SubjectcharacteristicsatbaselineCharacteristicIFCR-LIFCR-Fn2826Age(y)47±248±2AfricanAmerican1618Asian32Caucasian42Hispanic54Bodyweight(kg)95±394±3Height(cm)165±2164±2Bodymassindex(kg/m)35±135±1Valuesreportedasmean±SEM.IFCR-L:Intermittentfastingcalorierestriction-liquiddiet;IFCR-F:Intermittentfastingcalorierestriction-foodbaseddiet.Nodifferencesbetweengroupsforanyparameter(Independentetal.Nutrition&MetabolismPage4of8http://www.nutritionandmetabolism.com/content/9/1/98 DiscussionThisstudyisthefirsttoshowthatIFCRwithliquidmealscanproducepotentdecreasesinCHDrisk,andthattheseeffectsaremediatedinpartbyimprovementsinadipokines.Morespecifically,weshowherethatIFCR-LisaneffectivediettherapytomodulatelipidindicatorsofCHDrisk,i.e.reduceLDLcholesterol,tri-glycerides,andtheproportionofsmallLDLparticles,whileincreasingLDLpeakparticlesize.Ourfindingsalsodemonstratethatthesefavorablechangesinlipidswererelatedtoreducedwaistcircumference(visceralfatmass)andreductionsinpro-atherogenicadipokines,suchasleptinandTNF-alpha.Althoughbothoftheinterventionsproducedfavorablechangesinlipids,superiormodulationswereshownintheIFCR-LgroupwhencomparedtotheIFCR-Fgroup.ThereductionsinplasmalipidsbyIFCR-L(LDL-cholesterol:19%,triglycerides:20%)aresimilartowhathasbeenreportedinprevioustrialsofIF[2,3].Forin-stance,inatrialbyWilliamsetal.[3],obesesubjectsconsumedavery-lowcaloriediet(VLCD;kcal/d)1dayperweek,andateadlibitumeveryotherdayoftheweek.After20weeksoftreatment,LDLcholesterolandtriglycerideconcentrationsdecreasedby10%and52%,respectively[3].InthetrialbyHarvieetal.[2],obesewomenunderwent2daysofVLCD(600kcal/d)andateadlibitumoneveryotherdayoftheweek,for24weeks.Post-treatmentLDLcholesterolandtrigly-ceridelevelswerereducedby10%and17%frombase-line[2].ThemechanismbywhichIFCRmodulatescirculatinglipidconcentrationsisnotclear.Nonethe-less,recentevidencefromCRstudiesindicatethattheoxidationofcirculatingfreefattyacids(FFA)isincreasedduringperiodsofweightloss,whileFFAsynthesisis Table2DietaryintakeandphysicalactivityduringtheweightlossperiodIFCR-LIFCR-FDietvariablesWeek3Week10ChangeWeek3Week10ChangeEnergy(kcal)1708±1351255±102453±2101694±1801444±132250±146Totalfat(g)54±651±113±1462±947±515±11Saturatedfat(g)20±218±32±422±418±2Monounsaturatedfat(g)22±217±35±526±417±1Polyunsaturatedfat(g)12±216±54±614±212±2Protein(g)75±584±129±1467±665±9Carbohydrates(g)226±20215±4911±60210±23174±2036±20Cholesterol(mg)215±27196±3619±51224±43169±2855±53Fiber17±123±76±820±216±2PhysicalactivityvariablesWeek3Week10ChangeWeek3Week10ChangeActivityexpenditure(kcal/d)249±28283±2734±76246±37258±4312±25Steps(steps/d)6975±5267375±426400±2615876±6216405±599529±610Sleep(h/d)6.4±0.46.0±0.20.4±1.06.2±0.55.5±0.40.7±0.5Valuesreportedasmean±SEM.IFCR-L:IFCR-L:Intermittentfastingcalorierestriction-liquiddiet(n=28);IFCR-F:Intermittentfastingcaloriebaseddiet(n=26).Changeexpressedasthedifferencebetweenweek3andweek10absolutevalues.Week3valuessignificantly(P0.05)differentfromweek10valueswithingroup(Repeated-measuresANOVA).Nosignificantdifferencebetweengroupsforanynutrientexceptenergy. Table3BodyweightandbodycompositionchangesduringtheweightlossperiodIFCR-LIFCR-FWeek3Week10ChangeWeek3Week10ChangeBodyweight(kg)95±391±34±194±291±2Fatmass(kg)45±142±13±145±143±1Fatfreemass(kg)50±149±21±149±148±1Waistcircumference(cm)103±197±16±1102±398±3Bodymassindex(kg/m)35±134±11±135±134±1Valuesreportedasmean±SEM.IFCR-L:IFCR-L:Intermittentfastingcalorierestriction-liquiddiet(n=28);IFCR-F:Intermittentfastingcaloriebaseddiet(n=26).Changeexpressedasthedifferencebetweenweek3andweek10absolutevalues.Week3valuessignificantly(P0.05)differentfromweek10valueswithingroup(Repeated-measuresANOVA).Absolutechangesignificantlydifferent(P0.05)betweentheIFCR-LandIFCR-Fgroup(Repeated-measuresANOVA).etal.Nutrition&MetabolismPage5of8http://www.nutritionandmetabolism.com/content/9/1/98 decreased[18].LoweravailabilityofprecursorFFA resultsinareductioninhepaticsynthesisandsecretion ofvery-lowdensitylipoprotein(VLDL)intoplasma. LowersecretionofVLDLcontributestoreducedplasma concentrationsofLDL,sinceVLDLisquicklyconverted toLDLinthecirculation[19].Althoughthismechanism hasonlybeendemonstratedforCR,itpossiblethatIFCR mayaltercirculatinglipidsinasimilarfashion. ThegreaterimprovementinlipidprofilebyIFCR-Lis mostlikelyduetothemorepronouncedreductionsin bodyweightandvisceralfatmassobserved.After8 weeksoftreatment,bodyweightandwaistcircumfer- ence,anindirectindicatorofvisceralfat,decreasedtoa greaterextentintheIFCR-L(4kgand6cm,respect- ively)whencomparedtotheIFCR-Fgroup(3kgand4 cm,respectively).ThegreaterweightlossbytheIFCR-L groupisnotsurprisingastheseindividualshadalarger dailycaloriedeficitrelativetotheIFCR-Fgroup(453 kcal/d,250kcal/d,respectively).Thesedecreasesinwaist circumferenceintheIFCR-Lgroupwererelatedto reductionsinLDLcholesterolconcentrations.Anaccu- mulationofadiposetissueinvisceraldepotsmaycon- tributetothedevelopmentofdyslipidemiainseveral ways.Forinstance,lipolysisoffattissueinvisceraladi- pocytesishigherthanthatofsubcutaneousadipocytes. ThiscanleadtoanaugmentedeffluxofFFAfromvis- ceraldepots[20].TheseFFAsreleasedfromvisceralfat arethencollectedbytheportalveinandreachtheliver atmuchhigherconcentrationsthantheydothesystemic circulation[20].Intheliver,theseFFAtriggertheaug- mentedproductionoftriglycerides,andtheelevatedse- cretionofVLDL[20].TheincreasedsecretionofVLDL thenresultsinhigherplasmalevelsofLDL[20].Inview ofthis,itisconceivablethatthedecreaseinvisceralfat Figure2 Changesinlipidindicatorsofcoronaryheartdiseaseriskduringtheweightlossperiod. Valuesreportedasmean±SEMchange betweenweek3and10.IFCR-L:Intermittentfastingcalorierestriction-liquiddiet(n=28);IFCR-F.Intermittentfastingcalorierestriction-fo od baseddiet(n=26). A. Totalcholesterol. B. LDLcholesterol. C. HDLcholesterol. D. Triglycerides. E. LDLpeakparticlesize. F. Proportionofsmall LDLparticles.*Week3valuessignificantly(P0.05)differentfromweek10valueswithinEgroup(Repeated-measuresANOVA).#Significantly different(P0.05)betweentheIFCR-LandIFCR-Fgroup(Repeated-measuresANOVA). Table4Changesinadipokinesduringtheweightlossperiod 1 IFCR-LIFCR-F Week3Week10Change 2 Week3Week10Change 2 Leptin(ng/ml)36.5±2.527.1±3.1 3 9.4±1.637.6±2.529.4±2.4 3 8.2±1.7 IL-6(pg/ml)3.1±0.32.5±0.3 3 0.6±0.33.1±0.43.3±0.40.2±0.4 TNF-alpha(pg/ml)1.6±0.31.2±0.3 3 0.4±0.11.2±0.31.1±0.2 0.1±0.1 C-Reactiveprotein(mg/dl)0.4±0.10.4±0.10±0.10.6±0.20.4±0.1 0.2±0.2 8-isoprostane(pmol/mg)1.8±0.11.9±0.10.1±0.11.8±0.11.9±0.10.1±0.1 IGF-1(ng/ml)67.7±3.860.8±4.2 3 6.9±2.369.6±3.867.6±5.4 2.0±4.9 1 Valuesreportedasmean±SEM.IFCR-L:Intermittentfastingcalorierestriction-liquiddiet(n=28);IFCR-F:Intermittentfastingcalorierestric tion-foodbaseddiet (n=26).IL-6:Interleukin-6,TNF-alpha:Tumornecrosisfactor-alpha,IGF-1:Insulin-likegrowthfactor-1. 2 Changeexpressedasthedifferencebetweenweek3andweek10absolutevalues. 3 Week3valuessignificantly(P0.05)differentfromweek10valueswithingroup(Repeated-measuresANOVA). Kroeger etal.Nutrition&Metabolism 2012, 9 :98 Page6of8 http://www.nutritionandmetabolism.com/content/9/1/98 byIFCRplayedaroleinthereducedLDLcholesterolconcentrationsshownhere.Decreasesinpro-atherogenicadipokines,suchasleptin(26%),IL-6(19%),TNF-alpha(25%),andIGF-1(10%)wereobservedbytheIFCR-Lgroup.Nochangesinadi-pokineswerenotedintheIFCR-Fgroup,however,whichismostlikelyduetoinsufficientweightlosstoachievechangesintheseparameters[21].ThedecreasesinleptinnotedherearesimilartothoseobservedbyHarvieetal.[2].After24weeksofIF,obesewomenexperiencedpotentreductionsinleptinof40%[2].Thegreaterreduc-tionsinleptininthisprevioustrialaremostlikelyduetothegreaterweightlossachievedwiththelongertrialdur-ation[22].IntheIFCR-Lgroup,lowerplasmaleptinwasrelatedtodecreasedtriglyceridelevels.Invitrostudiesdemonstratethatleptinisapotentstimulatoroflipolysisandfattyacidoxidationinadipocytesandothercelltypes[23].Accordingly,leptinisalsoaregulatorofcirculatingtriacylglycerolconcentrations[23].ReducedleptinlevelswerealsorelatedtolowerLDLcholesterollevelspost-treatment,thoughthemechanismbywhichleptinmaybeinvolvedinreducingLDLcholesterolconcentrationsisnotclear.Wealsoobservedapositiveassociationbe-tweenvisceralfatmassandleptinlevels.Thus,itispos-siblethatthedecreaseinvisceralfatbytheIFCR-Linterventionstimulatedareductioninleptin,whichinturncontributedtothelipidprofileimprovementsdemonstratedhere.ReductionsinTNF-alphawerealsocorrelatedtodecreasesinplasmatriglycerides.EvidenceinrodentmodelsindicatesthatTNF-alphainduceshyperlipidemiabyincreasinghepatictriglycer-ideproduction[24].Thus,areductionincirculatingTNF-alphabyIFCR-Lmayberelatedtothereduc-tionsintriglyceridesobserved.Thisstudyislimitedinthatitdidnotcarefullycontrolforfoodintakebyprovidingfood-basedmealstotheinter-ventiongroups,i.e.dinnermealfortheIFCR-Lgroup,and3meals/dfortheIFCR-Fgroup.Providingallthemealsduringthestudywouldallowforamorepreciseassess-mentofdietaryadherence.Anotherdisadvantageisthatonlyfemalesubjectswereemployed,andassuch,theap-plicabilityofthesefindingstomalesremainsuncertain.Takentogether,ourresultssuggestthatIFCRwithliquidmealsisaneffectivediettherapytoreducebodyweight,visceralfatmass,andlipidindicatorsofCHDrisk.OurfindingsalsodemonstratethatthebeneficialmodulationsinvasculardiseaseriskbyIFCRmaybemediated,inpart,byreductionsinvisceralfatmassandpro-atherogenicadi-pokines.Thisstudyisanimportantfirststeptounder-standingtheunderlyingmechanismsthatmediatethecardio-protectiveeffectsofthisnoveldietregimen.CompetinginterestsKAVhasaconsultingrelationshipwiththesponsoroftheresearch,lsagenix,CMKandMCKconductedtheclinicaltrial,analyzedthedata,andassistedwiththepreparationofthemanuscript.SBandJFTperformedthelaboratoryanalyses,andassistedwithdataanalyses.CCTperformedtheanalysisofdietaryintakedata.KAVdesignedtheexperimentandwrotethemanuscript.Allauthorsreadandapprovedthefinalmanuscript.FundingsourceThisstudywasfundedbyIsagenixLLC.,Chandler,AZ.AuthordetailsDepartmentofKinesiologyandNutrition,UniversityofIllinoisatChicago,Chicago,IL,USA.DepartmentofClinicalNutrition,RushUniversity,Chicago,IL,USA.Received:13August2012Accepted:5October2012Published:31October20121.MattsonMP,WanR:Beneficialeffectsofintermittentfastingandcaloricrestrictiononthecardiovascularandcerebrovascularsystems.JNutr2.HarvieMN,PegingtonM,MattsonMP,FrystykJ,DillonB,EvansG,etaleffectsofintermittentorcontinuousenergyrestrictiononweightlossandmetabolicdiseaseriskmarkers:arandomizedtrialinyoungoverweightwomen.IntJObes(Lond)3.WilliamsKV,MullenML,KelleyDE,WingRR:Theeffectofshortperiodsofcaloricrestrictiononweightlossandglycemiccontrolintype2DiabetesCare4.HeymsfieldSB,vanMierloCA,vanderKnaapHC,HeoM,FrierHI:managementusingamealreplacementstrategy:metaandpoolinganalysisfromsixstudies.IntJObesRelatMetabDisord5.TsaiAG,WaddenTA:Theevolutionofvery-low-caloriediets:anupdateandmeta-analysis.Obesity(SilverSpring)6.NorthcottJM,YeganehA,TaylorCG,ZahradkaP,WigleJT:Adipokinesandthecardiovascularsystem:mechanismsmediatinghealthanddisease.CanJPhysiolPharmacol7.KonstantinidesS,SchaferK,KoschnickS,LoskutoffDJ:plateletaggregationandarterialthrombosissuggestsamechanismforatherothromboticdiseaseinobesity.JClinInvest8.GoetzeS,BungenstockA,CzupallaC,EilersF,StawowyP,KintscherU,etalLeptininducesendothelialcellmigrationthroughAkt,whichisinhibitedbyPPARgamma-ligands.Hypertension9.TuomistoK,JousilahtiP,SundvallJ,PajunenP,SalomaaV:protein,interleukin-6andtumornecrosisfactoralphaaspredictorsofincidentcoronaryandcardiovasculareventsandtotalmortality.Apopulation-based,prospectivestudy.ThrombHaemost10.MadjidM,WillersonJT:Inflammatorymarkersincoronaryheartdisease.BrMedBull11.SinghU,DasuMR,YanceyPG,AfifyA,DevarajS,JialalI:HumanC-reactiveproteinpromotesoxidizedlowdensitylipoproteinuptakeandmatrixmetalloproteinase-9releaseinWistarrats.JLipidRes12.BasariciI,AltekinRE,DemirI,YilmazH:Associationsofisoprostanes-relatedoxidativestresswithsurrogatesubclinicalindicesandangiographicmeasuresofatherosclerosis.CoronArteryDis13.ShanahanCM,WeissbergPL:Smoothmusclecellphenotypesinatheroscleroticlesions.CurrOpinLipidol14.MatsuzawaY,FunahashiT,NakamuraT:Theconceptofmetabolicsyndr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Submit your next manuscript to BioMed Central and take full advantage of: Convenient online submission Thorough peer review No space constraints or color gure charges Immediate publication on acceptance Inclusion in PubMed, CAS, Scopus and Google Scholar Research which is freely available for redistribution Submit your manuscript at www.biomedcentral.com/submit Kroeger etal.Nutrition&Metabolism 2012, 9 :98 Page8of8 http://www.nutritionandmetabolism.com/content/9/1/98