JAMAPATIENTPAGE
                        IntermittentFasting
                        Intermittentfastinginvolvesintervalsoflimitingfoodintakeforextendedperiodsoftime.
                        Thisdietaryapproachmaybeusedforattemptsatweightloss,for                        Intermittent fasting diets may limit the amount of time during the day 
                        otherhealthobjectives,oraspartofsomereligiouspractices.Popu-                   when a person can eat or may involve fasting for an entire day on a certain 
                        lar intermittent fasting diets involve daily time-restricted feeding           number of days per week.
                        (such as 16-24 hours of fasting) or intermittent full-day fasting               
                                                                                                         Types of intermittent fasting
                        on2to4days(ormore)perweek.Someregimensallowverylow
                        calorieintake(500-700caloriesperday)onafastingday.                                  Fasting     Feeding
                        WhatHappenstotheHumanBodyDuringPeriods                                            16:8 hour daily time-restricted fasting
                        ofIntermittentFasting?
                        Afteran8-to12-hourperiodoffasting,theliverstartstobreakdown
                        fatty acids to produce ketone bodies. The human body uses ke-                          16 hours 
                        tonebodiesasanalternatesourceoffueltosustainvitalorgansand                             fasting
                        tissues when the typical source (glucose) is not available. Studies                                      8 hours
                        haveshownthatintermittentfasting decreases blood inflamma-                                               feeding
                        torymarkersandimprovesglucoseregulation.
                        DoesIntermittentFastingHelpPeopleLoseWeight?                                     Medical uses of intermittent fasting
                        Studieslastingbetween12weeksand12monthshaveshownnodif-                           Intermittent fasting may improve blood pressure, heart rate, cholesterol levels, 
                        ferenceinweightlosswhenintermittentfastingiscomparedwith                         and glycemic control. However, these improvements dissipate within weeks 
                        adailycalorie-restricteddiet.However,between27%and40%of                          after resumption of a normal diet.
                        thesestudyparticipantsdroppedoutofintermittentfasting,dem-
                        onstratingthechallengeofadherencetointermittentfastingdiets.                 ensure that nutritional needs are met. Intermittent fasting is not
                                                                                                     recommendedforpregnantorlactatingwomen,frailolderadults,
                        DoesIntermittentFastingImproveHealth?                                        individuals with immunodeficiency, or those with or at risk of eat-
                        Intermittent fasting has been shown to result in decreases in                ing disorders. Intermittent fasting may be dangerous for patients
                        blood pressure, resting heart rate, cholesterol and triglycerides,           withdiabetesduetotheincreasedlikelihoodofhypoglycemia(low
                        glucose, and insulin. While these improvements in cardiovascular             bloodsugar).Patientswithdiabetesorotherhealthconditionswho
                        risk factors typically begin within 2 to 4 weeks of starting an inter-       are considering trying an intermittent fasting diet should discuss
                        mittentfastingdiet,theydissipatewithinseveralweeksofresum-                   thepotentialbenefitsandriskswiththeirdoctorbeforestarting.
                        ing a normal diet.
                        PotentialRisksandSideEffectsofIntermittentFasting                                FORMOREINFORMATION
                        Intermittent fasting may produce side effects including weakness,                NationalLibraryofMedicine
                        hunger, dehydration, headaches, difficulty concentrating, low                    https://magazine.medlineplus.gov/article/5-questions-about-
                        blood pressure, or fainting. Discussion with a nutritionist or dieti-            intermittent-fasting
                        cian is recommendedbeforestartinganintermittentfastingdietto
                        Authors: ZhaopingLi,MD,PhD;DavidHeber,MD,PhD                                 TheJAMAPatientPageisapublicserviceofJAMA.Theinformationand
                        AuthorAffiliations:CenterforHumanNutrition,DavidGeffenSchoolofMedicineat     recommendationsappearingonthispageareappropriateinmostinstances,butthey
                        UCLA,LosAngeles,California.                                                  arenotasubstituteformedicaldiagnosis.Forspecificinformationconcerningyour
                        ConflictofInterestDisclosures:DrHeberreportedreceiptofpersonalfeesfrom       personalmedicalcondition,JAMAsuggeststhatyouconsultyourphysician.Thispage
                        HerbalifeNutrition.Nootherdisclosureswerereported.                           maybephotocopiednoncommerciallybyphysiciansandotherhealthcare
                                                                                                     professionalstosharewithpatients.Topurchasebulkreprints,emailreprints@
                        Sources:HorneBD,GrajowerMM,AndersonJL.Limitedevidenceforthehealth            jamanetwork.com.
                        effectsandsafetyofintermittentfastingamongpatientswithtype2diabetes.JAMA.
                        2020;324(4):341-342.doi:10.1001/jama.2020.3908
                        deCaboR,MattsonMP.Effectsofintermittentfastingonhealth,aging,anddisease.
                        NEnglJMed.2019;381(26):2541-2551.doi:10.1056/NEJMra1905136
               1338     JAMA October5,2021 Volume326,Number13 (Reprinted)                                                                                             jama.com
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