The Causation, Consequences and Prevention of Obesity
A Public Health PerspectiveBy
Prof Winston G Mendes Davidson, CD; JP; MBBS; DTM&HHead, School of Public Health & Health Technology
University of Technology7.6.18
Presented at Annual Medical Conference Medical Association of Jamaica
TheScopeofObesity
1. It is estimated that over 1 billion persons worldwide are overweight, more than 300 million of whom are clinically obese.(WHO Obesity & Overweight: http://www.who.int/)
2. In the United States, >60% of adults are overweight or obese, and the number of obese children and adolescents is dramatically increasing(Wyatt SB, Winters KP, Dubbert PMAm J Med Sci. 2006 Apr; 331(4):166-74)
ThePandemic:GLOBALObesity
• Given its high and increasing prevalence, obesity is considered to be at pandemic levels.
• This has been attributed to an increasing worldwide adoption of energy-dense diets and sedentary lifestyles, probably as a consequence of urbanization and economic globalization
(WHO Obesity & Overweight: http://www.who.int/)
ObesityandFataccumulationdefinedbybodymassindexandwaistcircumferencealsoriskofobesityrelated
Co-morbidities.
WHATCAUSESOBESITY?
Whatdowemeanby“Cause”
• A cause is an event, condition, or characteristic without which the disease or condition would not have occurred.
• Risk factors are surrogates of underlying causes
• It is therefore important to distinguish between “risk factors” and “causes”
CaseStudy:UNDERSTANDING thePublicHealthPrincipleof “Causation”
• TheCasestudyofatrafficaccident– TheNarrativeoftheaccident
• Thefundamentalquestion– Whatcausedtheaccident?
Apply:TheEpidemiologicalTriad
HOST –(Driver)
ENVIRONMENT–
(TheROAD)
AGENT-(TheVehicle)
The3BIGCs:Context,Circumstances,Conditionsandre-emergingepidemics
Past:Epidemics
Present:Re-emergingEpidemic
“EPI-QUAD”: THE MODEL OF CAUSATION OF OBESITYCopyright: Prof Winston Davidson 2016
ENVIRONMENT HOST (MAN) AGENT (FOOD)
ENVIRON. INFLUENCES
1. Natural Environment:
Climate Change2. Human
Ecosystem: Society Economic, Social, Political, Cultural,
Religious Historical
PSYCHO-BIOLOGICAL
(Program response) Early environmental Influences, Genetics, Stress, Exposure to food
FOODAvailability, Production, Marketing/
GlobalisationEnergy intake vs Energy Out-
put
Multiple compounding variables working together. In Different: ContextsCircumstances Conditions
4.
1, 2, 3 & 4 DYNAMIC MULTIPLE VARIABLES WORKING TOGETHER giving rise to the OBESITY PHENOMENON reflecting different Contexts Circumstances & Conditions
1. 2. 3.
The“Web”ofCausationofObesityROOTCAUSE PROXIMATECAUSE
Hill's Criteria for Causality• Strength of the Association• Consistency• Specificity• Temporality• Biological gradient• Plausibility/Coherence• Experiment• Analogy
"Cigarettesmokingiscausallyrelatedtolungcancerinmen;themagnitudeoftheeffectofcigarettesmokingfaroutweighsallotherfactors."
• Adapted from: http://www.endotext.org/obesity/obesity22/obesityframe22.htm
ConsequencesofObesity
Obesity&Metabolicsyndrome
• TheMetabolicSyndrome:Isaclusterofmetabolicriskfactorscomingtogetherinasingleindividual
* GLUT4 is one of 13 sugar transporter proteins (GLUT1-GLUT12, and HMIT) encoded in the human genome (Joost and Thorens, 2001; Wood ...
Major metabolic risk factors resulting from obesity
1) Artherogenicdyslipidaemia2) Borderline-hightotalcholesterolconcentrations,3) Raisedtriacylglycerol(Triglyceride)
concentrations,4) SmallLDLparticles,andlowHDLconcentrations),5) Raisedbloodpressure,3)Insulinresistanceandglucoseintolerance,4)Abnormalitiesinthecoagulationsystem(procoagulantstate)
Question:DoestheMetabolicSyndromefullyexplaintheconsequencesofobesityanditscomorbiditiesonhumanhealth
andDisease?
• Answer:–TheMetabolicSyndromeasdefinedisnecessaryandessentialbutNOTsufficienttoexplainthefullpictureoftheconsequencesofObesityonhumanhealthanddisease
1.Obesity:ConsequencesPoorNutrition&LackofExercise(TheChildhoodObesityLifeCycle)
2.Obesity:ConsequencesObesityStressorsandMentalIllness
(PhysicalandbehaviouralillnessesincludingDepression)
Obesity&Depression• Feelings of sadness, anxiety or stress often lead people to
eat more than usual. Unless you act to address these emotions, however, these short-term coping strategies can lead to long-term problems.
• Although women are slightly more at risk for having an unhealthy BMI than men, they are much more vulnerable to the obesity-depression cycle. In one study, obesity in women was associated with a 37 percent increase in major depression.
• There is also a strong relationship between women with a high BMI and more frequent thoughts of suicide.
http://www.apa.org/helpcenter/obesity.aspx
Obesityandotherbehaviouraldisorders
• Binge eating, a behaviour associated with both obesity and other conditions such as anorexia nervosa, is also a symptom of depression.
• A study of obese people with binge eating problems found that 51 percent also had a history of major depression
http://www.apa.org/helpcenter/obesity.aspx
3.Obesity:ConsequencesSleepDeprivationanditsdysfunctionalsequelae
OBESITY&SLEEPDEPRIVATIONp Obstructive sleep apnea syndrome (OSAS) is
strongly associated with obesity and inflammation
p In obesity, effected production of most adipocytes impacts on multiple functions such as (Ghrelin & Leptin)n appetite and energy balance, n immunity, n insulin sensitivity, n angiogenesis, n blood pressure, n lipid metabolism and haemostasis, n all of which are linked with cardiovascular disease
Sleep duration and cardio-metabolic risk: a review of the epidemiologic evidence Kristen L. Knutson, Ph.D.
Obesity&Sleep• DrKnutsonaccumulatedevidencefromexperimentaland
observationalstudiesofsleep.• Observationalstudiesrevealedcross-sectionalassociations
betweengettingfewerthansixhourssleepandincreasedbodymassindex(BMI)orobesity.
• The studies revealed how signals from the brain which control appetite regulation are impacted by experimental sleep restriction.
• Inadequate sleep impacts secretion of the signal hormones ghrelin, which increases appetite, and leptin, which indicates when the body is satiated.
• This can lead to increased food intake without the compensating energy expenditure.
ObesityandSleepinChildren
• The evidence suggests the association between inadequate sleep and higher BMI is stronger in children and adolescents.
• It also shows that sleep deficiency in lower socioeconomic groups may result in greater associated obesity risks.
4.Obesity:ConsequencesTherelationshipbetweenObesity andthe
naturalandsocialenvironments.(Thedevelopmentofchronicdiseasesincluding
cancersandgeneticdisorders)
ObesityandAirPollution• A study of New York City children found that those whose motherswere exposed to higher levels of polycyclic aromatic hydrocarbons(PAHs) during pregnancy had a greater risk of obesity at 5 and 7 yearsof age (Rundle et al. 2012)
• Airpollution,alongwithobesity,isariskfactorfornon-alcoholicfattyliverdisease(Kelishadi andPoursafa,2011)
• Obesityappearstoworsenthecardiovascularhealtheffectsofairpollution(Weichenthal etal.2014)
• Whenairqualityimproves,lungfunctionalsoimproves.YetastudyfromSwitzerlandfindsthatthisonlyholdstrueifthosepeoplearenotoverweightorobese(Schikowski etal.2013)
From Epidemiology Matters, by Katherine M. Keyes and Sandro Galea. Oxford University Press, 2014 (pages 94-95)
THEPREVENTIONOFOBESITYTheFourstagestheoryofpreventionisalogicalepidemiologicalframeworkdesignedtoensure:Stg1 Astateofhealthandwellnessisbuilt(healthresilience)andHealthystatusmaintained(Pre-PrimaryPrevention)Stg2 Healthrisksaremitigatedandnewcasesareavoided,detectedearlyandtreatedpromptly(PrimaryPrevention)- DecreaseIncidenceStg3 Oldandnewcasesaretreatedandpreventedfrombecomingtemporarilyorpermanentlydisabled(Secondaryprevention- DecreaseprevalenceStg4 Avertchronicityandrehabilitatepartiallydisabledcases(Rehabilitation)- Avertfurtherchronicity
HowmaycasebycasepreventionofobesitybeachievedbyPractitioners?
*5Pillarsofwellnessascountermeasurestotheconsequencesofobesitymustbepracticedatallfourstagesofprevention:
1. GoodnutritionvsPoorNutrition2. Regularexercise(Jamaicamoves)vsLackofexercise3. AdoptmeasurestocopewithstressvsAccepting
consequencesoftheviciouscycleofstress,mentalandphysicalharm
4. EnsureRestfulSleepvsSleepdeprivation5. SafeandHarmoniousenvironment vsHarmful/Toxic
livingandworkingenvironments*ThesemeasuresarereferredtoasthefivePillarsofWellness/AHealthylifestylepractice(W.Davidson- 1999)
TheFourStagesTheoryforthePreventionofObesity:AdoptingEpidemiologicalPrinciplesofPrevention
PreventionHARMONIOUS ADAPTATION of MAN
within the ENVIRONMENT/(Healthy Lifestyle)
COMMUNITY
State of Health(Wellbeing)
Non-InstitutionalResponse Institutional
Response
COMMUNITY
Risk reduction /Early detection & diagnosisIncidence interventionmeasures
Treatment and Repair (Prevalence interventionMeasures)
Rehabinterventionmeasures
Rising Costs: Prof W. Davidson. 1999. (copyright)
PRE-PRIMARY PREVENTIONBuilding Health Resilience and Maintaintenance Wellness)
PRIMARY P REVENTION (Decrease Incidence)
SECONDARY PREVENTION(Decrease Prevalence)
TERTIARY PREVENTION(Avert Chronicity)
Rehab Response
PreventiveCountermeasurestotheDynamic“Web”ofCausationofObesityROOTCAUSE PROXIMATECAUSE