Obesity

1. The Causation, Consequences
and Prevention of Obesity
A Public Health Perspective
By
Prof Winston G Mendes Davidson, CD; JP; MBBS; DTM&H
Head, School of Public Health & Health Technology
University of Technology
7.6.18
Presented at Annual Medical Conference Medical Association
of Jamaica

2. The Scope of Obesity
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)

3. The Pandemic: GLOBAL Obesity
• 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/)

4. Obesity and Fat accumulation defined by body mass index
and waist circumference also risk of obesity related
Co-morbidities.

5. WHAT CAUSES OBESITY?

6. What do we mean by “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”

7. Case Study: UNDERSTANDING the Public
Health Principle of “Causation”
• The Case study of a traffic accident
– The Narrative of the accident
• The fundamental question
– What caused the accident?

8. Apply: The Epidemiological Triad
HOST –
(Driver)
ENVIRONMENT
–
(The ROAD)
AGENT-
(The Vehicle)

9. The 3 BIG Cs: Context, Circumstances,
Conditions and re-emerging epidemics
Past: Epidemics
Present: Re-emerging
Epidemic

10. “EPI-QUAD”: THE MODEL OF CAUSATION OF OBESITY
Copyright: Prof Winston Davidson 2016
ENVIRONMENT HOST (MAN) AGENT (FOOD)
ENVIRON.
INFLUENCES
1. Natural
Environment:
Climate Change
2. Human
Ecosystem: Society
Economic, Social,
Political, Cultural,
Religious Historical
PSYCHO-
BIOLOGICAL
(Program response)
Early environmental
Influences, Genetics,
Stress, Exposure to
food
FOOD
Availability,
Production,
Marketing/
Globalisation
Energy intake
vs Energy Out-
put
Multiple compounding
variables working together.
In Different: Contexts
Circumstances 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.

11. The “Web” of Causation of Obesity
ROOT CAUSE PROXIMATE CAUSE

12. Hill's Criteria for Causality
• Strength of the Association
• Consistency
• Specificity
• Temporality
• Biological gradient
• Plausibility/Coherence
• Experiment
• Analogy
"Cigarette smoking is causally related to lung cancer
in men; the magnitude of the effect of cigarette
smoking far outweighs all other factors."
• Adapted from:
http://www.endotext.org/obesity/obesity22/obesityframe22.htm

13. Consequences of Obesity

14. Obesity & Metabolic syndrome
• The Metabolic Syndrome: Is a cluster of
metabolic risk factors coming together in a
single individual

16. * GLUT4 is one of 13 sugar transporter proteins (GLUT1-GLUT12, and HMIT)
encoded in the human genome (Joost and Thorens, 2001; Wood ...

17. Major metabolic risk factors resulting
from obesity
1) Artherogenic dyslipidaemia
2) Borderline-high total cholesterol concentrations,
3) Raised triacylglycerol (Triglyceride)
concentrations,
4) Small LDL particles, and low HDL concentrations),
5) Raised blood pressure,
3) Insulin resistance and glucose intolerance,
4) Abnormalities in the coagulation system
(procoagulant state)

18. Question:
Does the Metabolic Syndrome fully
explain the consequences of obesity
and its comorbidities on human health
and Disease?

19. • Answer:
–The Metabolic Syndrome as
defined is necessary and essential
but NOT sufficient to explain the
full picture of the consequences of
Obesity on human health and
disease

20. 1. Obesity: Consequences
Poor Nutrition & Lack of Exercise
(The Childhood Obesity Life Cycle)

22. 2. Obesity: Consequences
Obesity Stressors and Mental Illness
(Physical and behavioural illnesses including
Depression)

23. 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

24. Obesity and other behavioural
disorders
• 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

25. 3. Obesity: Consequences
Sleep Deprivation and its dysfunctional sequelae

26. OBESITY & SLEEP DEPRIVATION
 Obstructive sleep apnea syndrome (OSAS) is
strongly associated with obesity and
inflammation
 In obesity, effected production of most
adipocytes impacts on multiple functions such as
(Ghrelin & Leptin)
 appetite and energy balance,
 immunity,
 insulin sensitivity,
 angiogenesis,
 blood pressure,
 lipid metabolism and haemostasis,
 all of which are linked with cardiovascular disease

27. Sleep duration and cardio-metabolic risk: a review of the
epidemiologic evidence Kristen L. Knutson, Ph.D.

28. Obesity & Sleep
• Dr Knutson accumulated evidence from experimental and
observational studies of sleep.
• Observational studies revealed cross-sectional associations
between getting fewer than six hours sleep and increased
body mass index (BMI) or obesity.
• 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.

29. Obesity and Sleep in Children
• 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.

30. 4. Obesity: Consequences
The relationship between Obesity and the
natural and social environments.
(The development of chronic diseases including
cancers and genetic disorders)

31. Obesity and Air Pollution
• A study of New York City children found that those whose mothers
were exposed to higher levels of polycyclic aromatic hydrocarbons
(PAHs) during pregnancy had a greater risk of obesity at 5 and 7 years
of age (Rundle et al. 2012)
• Air pollution, along with obesity, is a risk factor for non-
alcoholic fatty liver disease (Kelishadi and Poursafa, 2011)
• Obesity appears to worsen the cardiovascular health effects
of air pollution (Weichenthal et al. 2014)
• When air quality improves, lung function also improves. Yet a
study from Switzerland finds that this only holds true if those
people are not overweight or obese (Schikowski et al. 2013)

32. From Epidemiology Matters, by Katherine M. Keyes
and Sandro Galea. Oxford University Press, 2014
(pages 94-95)

34. THE PREVENTION OF OBESITY
The Four stages theory of prevention is a logical
epidemiological framework designed to ensure:
Stg 1 A state of health and wellness is built (health
resilience) and Healthy status maintained (Pre-Primary
Prevention)
Stg 2 Health risks are mitigated and new cases are
avoided, detected early and treated promptly (Primary
Prevention)- Decrease Incidence
Stg 3 Old and new cases are treated and prevented from
becoming temporarily or permanently disabled
(Secondary prevention- Decrease prevalence
Stg 4 Avert chronicity and rehabilitate partially disabled
cases (Rehabilitation)- Avert further chronicity

35. How may case by case prevention of
obesity be achieved by Practitioners?
*5 Pillars of wellness as countermeasures to the
consequences of obesity must be practiced at all four
stages of prevention :
1. Good nutrition vs Poor Nutrition
2. Regular exercise (Jamaica moves) vs Lack of exercise
3. Adopt measures to cope with stress vs Accepting
consequences of the vicious cycle of stress, mental and
physical harm
4. Ensure Restful Sleep vs Sleep deprivation
5. Safe and Harmonious environment vs Harmful /Toxic
living and working environments
*These measures are referred to as the five Pillars of Wellness / A Healthy lifestyle
practice (W. Davidson- 1999)

36. The Four Stages Theory for the Prevention of Obesity:
Adopting Epidemiological Principles of Prevention
Prevention
HARMONIOUS
ADAPTATION of MAN
within the
ENVIRONMENT/
(Healthy Lifestyle)
COMMUNITY
State of Health
(Wellbeing)
Non-Institutional
Response Institutional
Response
COMMUNITY
Risk reduction /
Early detection & diagnosis
Incidence intervention
measures
Treatment
and Repair
(Prevalence
intervention
Measures)
Rehab
intervention
measures
Rising Costs:
Prof W. Davidson. 1999. (copyright)
PRE-PRIMARY PREVENTION
Building Health Resilience and
PRIMARY P REVENTION
(Decrease Incidence)
SECONDARY PREVENTION
(Decrease Prevalence)
TERTIARY PREVENTION
(Avert Chronicity)
Rehab
Response

37. Preventive Countermeasures to the
Dynamic “Web” of Causation of Obesity
ROOT CAUSE PROXIMATE CAUSE