Obesityisdefinedasexcessiveaccumulationoffattissue(Adipose
Tissue)in body.Many factors contribute to obesity including genetic,
environmental,culturaletc.BodyMass Index (BMI)is usuallyused to
determineweatherapersonisnormal,overweight,obeseorsevereobese.In
otherwordsamanisobeseiffataccountsfor25%ofhisbodyweight,anda
womanissaidtobeobeseiffataccountsfor35%ofherbodyweight.Other
clinicalindicatorsofobesityincludewaist-hipratioandskinfoldthickness.
TheWorldWatchInstitutehasestimatedthatthenumberofoverweight
peopleinWorldisasgreatasthenumberofunderfedpeople.
Bariatrics:Thestudyofobesityanditscauses,prevention,andtreatment.
BodyMassIndexisthetotalbodymassinKgdividedbysquareofheightin
meters.
AccordingtoNationalInstituteofHealthnormalBMIis18.5to
24.9Kg/m2.WorldHealthOrganizationrecommendsthatamongAsians
BMI>23isoverweightandBMI>25isobese.
IfBMIis18.5to24.9,thepersonisnormal
IfBMIis25to29.9,thepersonisoverweight
IfBMIis>29.9,thepersonisobese
BMI=30to34.9(Class-Iobesity)
BMI=35to39.9(Class-IIobesity)
BMI>40(Class-IIIorextremeobesity)
Obesitydefinitelyrunsinfamilies.20to25% casesofobesityare
causedbygeneticfactors.OppositeofobesityisInanition;definedas
excessiveweightloss.
Causesofobesity
1.Sedentarylifestylewithchronicintakeofhighcaloriediet
2.Genetic influence (However mostof obesity develops from
mutation in multiple genes plus environmentalfactors and
behavior).Identicaltwinstendtohavesimilarbodyweight
3.Snacking,lossofregularmeals,energydensefood,carownership,
automationandtimespentoncomputer,games&watchingTVare
somefactorsthatcontributetoobesity
4.MutationofMelanocortin-4receptor(MC4R)causesmorbidobesity
inchildren
5.Endocrine Disorders e.g Hypothyroidism,Cushing Syndrome,
Insulinoma,Hypothalamic injury/Hypothalamic tumor. Growth
hormonedeficiencyresultsinmildtomoderatecentralobesity
(abdominalobesity)
6.Drugs, e.g Antipsychotics, Sulphonylureas, Thiazolidinedions,
Insulin,Pizotefin,Corticosteroids,Sodium Valproate,and beta blockers
7.Chronicalcoholconsumption.Alcoholitselfisamajorenergy
source
8.Destruction of Ventro-medial nuclei (Satiety Center) of
hypothalamus,thepersonbecomesobesefourtimesthenormalin
thiscondition.InanormalpersonstimulationofVentro-medial
nuclei(satietycenter)ofhypothalamuscausescessationofeating,
whereaslesioninthisregioncauseshyperphagiaandsyndromeof
HypothalamicObesity
9.Lesionofparaventricularnucleiofhypothalamus.(Hypothalamus
playsakeyroleincentralregulationofappetite)
10.Orexigenicsubstances(substancesthatincreaseappetitee.gbetaendorphin,ghrelin,neuropeptide-Y,Orexin-A&Orexin-B)
11.Defectinmelanocortinsignalingpathwaycausesextremeobesity
12.Leptin:a167 amino acid circulating proteinhormoneactson
hypothalamus to decrease food intake and increase energy
consumption.NoLeptinproductionormutationofleptinreceptors
inhypothalamuscausesmarkedhyperphagialeadingtomorbid
obesity.Wheninfusedintothecerebralventriclesleptincauses
boneloss.Leptinisreleasedfromadipocytes
13.Stressfulsituationandmentaldepression
14.Over-nutritionofchildrenespeciallyininfancycauseslifetime
obesity
15.Hypophysialtumorsthatencroachintohypothalamus
16.Excessivecortisolesecretiondevelopesapeculiartypeofobesity
withexcessivefatdepositioninchestandheadregiongivinga
MoonFace
17.Hormonalimbalance(Glucagon,CCK,Leptin,Oxytocin,PeptideYY,
Somatostatin,alphaMSH,beta-endorphin,ghrelin,neuropeptide-Y,
orexin-A&Orexin-B,Insulin)
18.FoodswithhighglycemicIndexe.gbakedpotato,whitebreadand
whiterice
19.ChildrenwithPrader-WilliSyndromeandwithLaurence-Moon-Biedl
Syndromearecharacteristicallyobese.(Prader-WilliSyndromeis
due to deletion ofa partofchromosome-15;the affected
individuals overeat. Laurence-Moon-Biedl Syndrome is an
autosomalrecessivegeneticdisorder)
20.Diminished amountofThermogenin-a mitochondrialprotein
presentinbrownadiposetissuethatdissipatesenergyasheat
HEALTHHAZARDSOFOBESITY
1.Obesity along with physical inactivity, Diabetes Mellitus,
Hypertension,Hyperlipidemia and cigarette smoking generally
increasetheriskforAtherosclerosis 2.AbdominalObesity(alsoknownasvisceralobesity,Androidobesity,
& Apple shaped obesity) causes insulin resistance. Fat
accumulationinvisceralabdominalorgansismoredangerousthan
subcutaneousfataccumulationabdomen.Obesityaloneisthe
mostimportantenvironmentalfactorcausinginsulinresistance.
Visceralobesitydue to accumulation offatin omentum and
mesentericregioncorrelateswithinsulinresistance.Subcutaneous
abdominalobesity have much less association with insulin
resistance
3.Obesity/weightgainplussedentarylifestyleaccountsfor65to75%
riskofprimaryhypertension.Itisduetothefactthatobesityis
associatedwithanincreasedintravascularvolume,elevatedcardiac
output,activation ofRenin-Angiotensin system and increased
sympatheticoutflow
4.Obesityleadstochronicrenalfailure.Uncontrolledhypertension
withobesitycausesseverevascularinjurycausingcompletelossof
kidneyfunction
5.ObesityisanindependentriskfactorforCoronaryHeartDisease
(CHD)inwomen.Obesitycausesdeviationofelectricaxisofheart.
6.Anabdominalcircumferenceof>102cm inmenor>88cm in
women indicates that risk of metabolic and cardiovascular
complication ofobesity is high e.g diabetes mellitus,stroke,
coronaryarterydiseaseandearlydeath.Abdominalobesitymay
contributetoGastroesophagealRefluxDisease(GERD)mainlydue
to increased intra-abdominal pressure which contribute to
dysfunctionofgastro-esophagealjunctionandincreasedlikelihood
ofhiatalhernia
7.Upperbodyobesity(waist,flank)isgreaterhealthhazardthanlower
bodyobesity(thigh,buttocks)
8.Reproductive problems e.g irregular periods, Deep Venous
Thrombosis(DVT)andobstructivesleepapneaarealsoassociated
withobesity
9.ObesityworsensPsoriasis
10.ObesitylowersHighdensitylipoproteins(HDL),andincreaseLow
densitylipoproteins(LDL),bloodglucoseandfreetriglyceridesin
blood leading to high blood pressure,atherosclerosis and
myocardialinfaraction
11.Beingoverweightislinkedtomanymalignancies,includingbreast
and uterinecancerin women and colorectal,esophageal,and
kidneycancerinbothmenandwomen.Mortalityratefrom cancer
isincreasedinobeseindividualsascomparedwithnormalones.
12.Obesity aggravates pain atmostsites ofthe body through increasingmechanicalstrainandisariskfactorformorerapid
progressionofjointdamageinpatientswitharthritis
13.Non-AlcoholicFattyLiverDisease(NAFLD)isstronglyrelatedto
obesity,dyslipidemia,insulin resistance and type-IIDiabetes
Mellitus
14.Polycystic Ovarian Syndrome (PCOS)is often associated with
obesity.PCOSischaracterizedbychronicanovulation,polycystic
ovariesandhyperandrogenism.Elevatedestrogrnlevelsareseenin
obesewomen.Somestudiessuggestthatoralcontraceptivesare
lesseffectiveinoverweightwomen.Inadditionobesityisarisk
factorforthrombo-emboliccomplications
15.ObesitypredisposesapersontoMetabolicSyndrome.Metabolic
Syndromeisdefinedasthepresenceofanythreeofthefollowing:
Waistmeasurementof40inchesormoreformen
and35inchesormoreforwomen
BloodTriglyceridelevelof150mg/dL(1.7mmol/L)
orabove
HDL Cholesterol level less than 40 mg/dL
(1.44mmol/L)formen & less than 50 mg/dL
(1.8mmol/L)forwomen
Bloodpressureof130/85mmHgorabove
Fasting blood glucose levels of100 mg /dL
(5.5mmol/L)ormore
16.Obesityisariskfactorfordevelopmentofasthmaandcauses
restrictivepulmonaryfunctionwhichmayincreasepulmonaryrisk insurgicalpatients.ObesitycausesPickwickianSyndrome(Obesity
-Hypoventilation Syndrome) characterized by alveolar
hypoventilationcausedbycombinationofbluntedventilatorydrive
andmechanicalloadonchestbyobesity
17.Obesity is a risk factorforgallstones especially in women.
Gallstonesaremorecommoninwomenthaninmenandincrease
inincidencewithageinbothsex
18.Obesityalongwithpoorhealthandagingisthemaincauseof
acquiredhypogonadotrophichypogonadism (serum testosteronein
therangeof150to300ng/dL)
TREATMENTOFOBESITY
Successfulweightlosscanbeachievedbymultidisciplinaryapproachthat
includes
Exercise
Lowcaloriediet
Changingeatingbehavior
Exerciseincreasesdailyenergyexpenditureandisusefulforlongterm
weightmaintenance.Exerciseplusdietresultsingreaterweightloss
thandietalone.Exerciseshouldbeincorporatedindailyliferoutine.
Forced exercise is an essentialpart of treatment of obesity.
Sympatheticstimulationbyincreasingthermogenesishelpstolimit
excessweightgain.Atleast60minutesofdailymoderateintensity
physicalactivitymaybenecessaryto maximizeweightlossand
preventsignificantweightgain.
Lowcaloriediet:Foreach9.3Cexcessenergyintake1gram offatis
storedinbody.Limitingfoodsthatprovidelargeamountofcalorie
withoutothernutrientse.gfat,sucrose,andalcohol.Lowcarbohydrate
dietissafeandeffectiveforweightloss.Patientswithsevereobesity
mayrequiremoreaggressivetreatmentregimens,VeryLow Calorie
DietVLCD (800 Kcal/day)are usefulforrapid weightloss and
improvementinobesityrelatedcomplications.Advisethepatientto
increasePhysicalActivityLevel(PAL)ratios.Eatingfoodswithlow
glycemicindexhelpstoreduceweightgain;lowglycemicindexfoods
includemanyfruits,vegetables,grainybread,pasta,andlegumes.High
glycemicindexfoodsincludebackedpotato,whitebreadandwhiterice.
Exerciseincreasesdailyenergyexpenditureandisusefulforlongterm
weightmaintenance.Exerciseplusdietresultsingreaterweightloss
thandietalone.Exerciseshouldbeincorporatedindailyliferoutine.
Forced exercise is an essentialpart of treatment of obesity.
Sympatheticstimulationbyincreasingthermogenesishelpstolimit
excessweightgain.Atleast60minutesofdailymoderateintensity
physicalactivitymaybenecessaryto maximizeweightlossand
preventsignificantweightgain.
Lowcaloriediet:Foreach9.3Cexcessenergyintake1gram offatis
storedinbody.Limitingfoodsthatprovidelargeamountofcalorie
withoutothernutrientse.gfat,sucrose,andalcohol.Lowcarbohydrate
dietissafeandeffectiveforweightloss.Patientswithsevereobesity
mayrequiremoreaggressivetreatmentregimens,VeryLow Calorie
DietVLCD (800 Kcal/day)are usefulforrapid weightloss and
improvementinobesityrelatedcomplications.Advisethepatientto
increasePhysicalActivityLevel(PAL)ratios.Eatingfoodswithlow
glycemicindexhelpstoreduceweightgain;lowglycemicindexfoods
includemanyfruits,vegetables,grainybread,pasta,andlegumes.High
glycemicindexfoodsincludebackedpotato,whitebreadandwhiterice.
NationalInstituteofHealthguidelinesrecommendsadecreasein
caloricintakeof500Kcal/dayforoverweightandmoderatelyobese
persons(withBMIgreaterthan25andlessthan35Kg/m2)toachieve
aweightlossof1pound/week.
Itisimportanttopreventvitamindeficiencyduringdietingperiod.In
ordertopreventmuscledegradationduringdietingperiodproteinintake
perdayshouldnotbelessthan50gramsformenand40gram for
women.
Medications:SeveraldrugsareapprovedbyFDA fortreatmentof
obesity,butsideeffectprofileofmanydrugshaslimitedtheiruse.
Followingarethedrugsusedtotreatobesity.
CatecholaminergicMedications(forshorttermtreatmentonly)
Lorcaserin(Belviq)isselectiveserotoninreceptoragonist(side
effects:increasedriskofvalvularheartdiseaseandpsychiatric
sideeffects)
Combination of Phentermine & Toperamine (Qsymia).
Phentermine stimulates release of norepinephrine from
hypothalamus,andToperaminereducesappetite(sideeffects:
moodchange,fatigue,insomnia,increasedheartrate,andbirth
defects)
BupropionandNaltraxone(NOTAPPROVEDduetoincreased
cardiovascularrisk)
Sibutramineisanimportantweightlossmedication,dueto
increasedcardiovasculareventsitsuseislimited
Rimonabant(psychiatricsideeffects)
OnlyonedrugOrlistat(Xenical/Orlifit)islicensedforlong
term usetotreatobesity.Orlistatinhabitsgastricand
pancreaticlipasetherebydecreasingthedigestionand
absorptionofingestedfatandfatsolublevitamins.For
longterm treatmentofobesityOrlistat120mgorallyup
to3timesadayafterfatrichmealisapproved.
BariatricSurgery:Itisreservedforthepatientswithsevereobesity
(BMI>40)orthosewithBMI>35plussignificantcomplicationse.g
DiabetesMellitusType-2orObstructiveSleepAponea.Bariatricsurgery
results in protein malnutrition,vitamin and mineraldeficiencies.
Clinicallysignificantdeficienciesincalcium,folicacid,ironandvitamin
D,B-12,A and K are common.There are fourbariatricsurgical
procedures,
I.GastricBanding
II.SleeveGastrectomy
III.Rox-en-YGastricbypass
IV.Duodenalswitch
Thanks.