Epidemiology of Obesity
Lecture handout by
Prof. Ashry Gad Mohamed
&
Dr Amna Rehana Siddiqui
Department of Family and Community Medicine
Objectives
• Understand the terms overweight and obesity
• Recognize the methods to diagnose
overweight and obesity
• Discuss the distribution of obesity by gender &
age groups in Saudi Arabia & other settings
• Know the determinants and consequences of
obesity
• Outline approach to control obesity
No body is exempted from obesity . It can be you.
Terms Obesity and Overweight
• Obesity is excessive fat accumulation in adipose
tissue to the extent that it can affect health
• When a person is "overweight", it means that they
have more body fat than they need for their body to
function.
• Weight ranges are greater than what is generally
considered healthy for a given height
• Such ranges of weight increase the likelihood of
certain diseases and health problems.
Measuring Obesity
Body Mass Index (BMI)
• Calculated from a person's weight and height.
• Reliable indicator of body fatness for most people.
• Inexpensive & easy-to-perform screening for weight
categories that may lead to health problems.
• Does not measure body fat directly, but correlates to
direct measures of body fat like;
–
–
–
–
Skin fold thickness
underwater weighing
dual energy x-ray absorptiometry (DXA)
alternative for direct measures of body fat.
Obesity classification.
•
Obesity is further divided
into three separate classes,
with Class III obesity being
the most extreme of the three.
With a BMI of:
You are considered:
Below 18.5
Underweight
18.5 - 24.9
Healthy Weight
25.0 - 29.9
Overweight
30 or higher
Obese
CDC, NHLBI
Obesity class
BMI (kg/m2)
Class I
30.0- 34.9
Class II
35.0-39.9
Class III
≥ 40.0
(Extreme Obesity)
Body Mass Index (BMI): Western Settings
• BMI= Wt.(kg.) / Ht.2(meters2)
• BMI= Wt (lbs) / Ht 2 (inches)
Height
Weight Range
BMI
Considered
124 lbs or less
Below 18.5
Underweight
125 to 168 lbs
18.5 to 24.9
Healthy
weight
169 to 202 lbs
25.0 to 29.9
Overweight
203 lbs or >
30 or higher
Obese
5' 9"
Obesity Assessment
• Increased body weight does not always
equate to increased body fat.
• For example, a professional football player
could weigh 260 pounds and be six feet tall
with no excess fat, just increased lean body
mass.
Mortality Data and BMI
• The mortality data is U - or J -shaped conformation in
relation to weight distribution.
• Notable racial spectrum
• Ideal BMI for Asians is substantially lower than that for
Caucasians.
• For subjects with severe obesity (BMIs ≥40), life expectancy
is reduced by as much as 20 years in men and by about 5
years in women.
• Coexisting obesity and smoking are associated with even
greater risks than these alone for premature mortality.
Disease Risk Associated With Different Levels Of BMI
And Waist Circumference In Adult Asians
Weight
Categories
BMI
(kg/m2)
Obesity
Class
Disease Risk
(Relative to Normal Weight and Waist Circumference)
Men
< 35 in (<90cm)
Women < 31 in ( < 80cm)
Underweight
>35 in (>90 cm)
31 in (>80 cm)
< 18.5
Low
Average
Normal
18.5-22.9
Average
Moderate
Overweight
23.0-24.9
Moderate
Increased
Obesity
25-29.9
I
Increased
High
Extreme
Obesity
≥30
II
High
Very High
Adapted from Redefining Obesity and its Treatment: The Asia-Pacific Perspective. WHO 2000
13
Global Prevalence of Obesity in Adult Males
With examples of the top 5 Countries in each
Region
North America
USA 31%
Mexico 19%
Canada (self report) 17%
Guyana 14%
Bahamas 14%
% Obese
0-9.9%
10-14.9%
15-19.9%
20-24.9%
25-29.9%
≥30%
Self Reported data
European Region
Croatia 31%
Cyprus 27%
Czech Republic 25%
Albania (urban) 23%
England 23%
Eastern
Mediterranean
Lebanon 36%
Qatar 35%
Jordan 33%
Kuwait 28%
Saudi Arabia 26%
South Central America
Panama 28%
Paraguay 23%
Argentina (urban) 20%
Uruguay (self report) 17%
Dominican Republic 16%
Africa
South Africa 10%
Seychelles 9%
Cameroon (urban) 5%
Ghana 5%
Tanzania (urban) 5%
With the limited data available, prevalence's are not age standardised. Self reported surveys may
underestimate true prevalence. Sources and references are available from the IOTF.
© International Obesity TaskForce, London –January 2007
South East Asia
Pacific Region
Nauru 80%
Tonga 47%
Cook Island 41%
French Polynesia
Samoa 33%
Global Prevalence of Obesity in Adult Females
With examples of the top 5 Countries in each
Region
European Region
Albania 36%
Malta 35%
Turkey 29%
Slovakia 28%
Czech Republic 26%
Eastern
Mediterranean
Jordan 60%
Qatar 45%
Saudi Arabia 44%
Palestine 43%
Lebanon 38%
North America
USA 33%
Barbados 31%
Mexico 29%
St Lucia 28%
Bahamas 28%
% Obese
0-9.9%
10-14.9%
15-19.9%
20-24.9%
25-29.9%
≥30%
Self Reported data
South Central America
Panama 36%
Paraguay 36%
Peru (urban) 23%
Chile (urban) 23%
Dominican Republic 18%
Africa
Seychelles 28%
South Africa 28%
Ghana 20%
Mauritania 19%
Cameroon (urban) 14%
With the limited data available, prevalence's are not age standardised. Self reported surveys may
underestimate true prevalence. Sources and references are available from the IOTF.
© International Obesity TaskForce, London –January 2007
South East Asia
Pacific Region
Nauru 78%
Tonga 70%
Samoa 63%
Niue 46%
French Polynesia
BMI and Body Fat
• At the same BMI, women tend to have more
body fat than men.
• At the same BMI, older people, on average,
tend to have more body fat than younger
adults.
• Highly trained athletes may have a high BMI
because of increased muscularity rather than
increased body fatness.
Abnormal Fat Distribution
• Upper body subcutaneous fat is a marker for
intra-abdominal fat in men and women.
• Men accumulate upper body fat.
• Women can accumulate upper & lower body
fat
Measuring Body Fat
Fat depots can be measured with skin-fold calipers.
• Males: Upper Chest, Upper Abdomen
• Female: Triceps, Lower Abdomen, Thighs
Waist Circumference: While standing place a tape
measure just above the hipbones; after breathing out.
Risk of heart disease and diabetes mellitus increases in
• Males: > 40 inches (western Setting) > 35 inches (Asians)
•
Females: > 35 inches (Western Setting) > 31 inches (Asians)
Obesity & Overweight
in Children & Adolescents
• Overweight is defined as a BMI at or above
the 85th percentile and lower than the 95th
percentile for children of the same age and
sex.
• Obesity is defined as a BMI at or above the
95th percentile for children of the same age
and sex.1
Obesity in Children & Adolescence
• Children and particularly adolescents who are
obese have a high probability of growing to be
adults who are obese.
• Obesity epidemic is expected in next decades
• Adolescent obesity poses a serious risk for
severe obesity during early adulthood,
Correlation: BMI and Adverse health
• Overall morbidity and mortality increases
exponentially at a calculated BMI of greater
than 30.
• At any given BMI women have a greater
percent body fat than men, so other methods
are also needed to assess body fat clinically.
Distribution of Obesity
Obesity by Gender 1999-2003
% of Total population
Reference: Last Slide; http://www.economist.com/node/8846631
Obesity prevalence: Global
• 250 million people (~ 7% of the world) are obese.
• Overweight rate is 2-3 times more of obesity
• Socioeconomic status (SES) and prevalence of
obesity are negatively correlated in developed
countries
• Correlation between SES and Obesity is reversed
in many undeveloped countries
Obesity prevalence: International
• The prevalence of obesity is increasing world wide
• MONICA study from Europe reports that 15% of men
and 22% of women are obese in Europe
• Malaysia, Japan, Australia, New Zealand, and China
detailed obesity epidemic in the past 2-3 decades.
• Middle Eastern countries; show a disturbing trend,
with alarming levels of obesity often exceeding 40%
and particularly worse in women than in men.
Epidemiology of Obesity in USA
• About 100 million adults in the United States are at
least overweight or obese.
• 35% of women and 31% of men older than 19 years
are obese or overweight.
• 20-25% of children are either overweight or obese,
• Prevalence is greater in some minority groups
• Obesity management costs about $100 billion / year,
without the costs of various commercial dietary and
weight-loss programs.
Demographic Prevalence of Obesity (BMI>30) :
USA MMWR August 2010
%
MMWR: Morbidity and Mortality Weekly Report CDC USA
Demographic Prevalence of Obesity in
Saudi Arabia (BMI>30kg/m2) 1990-1993
National Chronic Diseases metabolic Survey 1990-93 MOH & King Saud University
Women’s obesity by educational attainment
Marmot M, Clinical Medicine, 2006
Prevalence of overweight, obesity, and severe
obesity in children & Adolescents (N=19,317;
age 5 – 18 years) Saudi Arabia 2005
Ref: El-Mouzan et al. Prevalence of overweight and obesity in Saudi children and adolescents
Annals of Saudi medicine 2010; Vol 30 (3) : 203-208
Figure 1
Percentage increase in BMI categories since 1986
(source: Behavioral Risk Factor Surveillance Survey; results adjusted for changes in population demographics for 2005 .
Source: Sturm R. Public Health 2007; 121:492-496 (DOI:10.1016/j.puhe.2007.01.006 )
Regional (local) studies showing the prevlanece of obesity and overweight
Author , and place of
study
Khashoggi et al
(1994)Attendees at PHC
jedahh
AL- Shammati et al
(1994b) Attendees at
PHC, Riyadh
AL- Jassir et al (1998)
Emploees of M.O.H
Riyadh
Age
group
11-70
years
Mean
age
32.2
Mean
male =
34
Female
32
20 and
above
No of
subjects
Criteria used
Prevalence
among
male %
Prevalence
among
Female%
Obese BMI >30
----
64.3
Overweight
BMI 25-29.9
----
26.8
852
female
Obese BMI >30
47.0
733 With
back pain
1238
males
Obese BMI >30
51.6
Overweight
BMI 25-29.9
40.3
----
Obese BMI >30
18.4
..…
Causes of Obesity
Primarily
• Dietary intake
• Physical Inactivity
• Eating patterns
• Eating environment
• Food availability
• Food packaging
• Eating environment
• Fast food linked to
increased adiposity
Some Secondary Causes
• Hypothyroidism
• Cushing’s Syndrome
• Hypothalamic Obesity
• Polycystic Ovarian Syndrome
• Growth Hormone deficiency
• Oral Contraceptives
• Pregnancy related
• Genetic Syndromes
• Medication Related
• Eating Disorder
Comorbidities
Genetic reasons for obesity
• A mutant gene
• A defective gene to produce Leptin ; a satiety
hormone that influences the appetite control
in hypothalamus
• Role of mutant genes in defective receptor
action is being studied
Causes of Obesity
A defective ob gene
causes inadequate
leptin production. Thus,
the brain receives an
under assessment of
body’s adipose stores
and urge to eat.
In addition to deficient
leptin production,
scientists also propose
the possibility of
defective receptor
action (via a leptin
receptor molecule on
brain cells), which
increases a person’s
resistance to satiety.
Causes of Obesity
• Characteristics of fast
food linked to increased
adiposity:
– Higher energy density
– Greater saturated fat
– Reduced complex
carbohydrates & fiber
– Reduced fruits and
vegetables.
Consequences of obesity
• Increase in morbidity & mortality rates.
• Reduced longevity in next few decades
• Increased risk and duration of lifetime disability.
• Obesity in middle age group is associated with poor
indices of quality of life at old age.
Ref: Insurance databases & large cohort studies from the Framingham and NHANES studies (USA)
Obese Syndrome Components
•
•
•
•
•
•
Glucose intolerance
Insulin resistance
Dyslipidemia
Type 2 diabetes
Hypertenision
Elevated plasma leptin
concentration
• Increased visceral adipose
tissue
• Increased risk of CHD &
some cancers
Factors associated with obesity modulate
morbidity and mortality
•
•
•
•
•
•
•
Age of onset of obesity
Duration of obesity,
Severity of obesity,
Amount of central adiposity,
Other co-morbidities,
Gender
Level of cardio-respiratory fitness.
Weight Loss Therapy is Recommended
• With BMI ≥ 23
• Waist measurement of:
≥ 90 cm for men and ≥ 80 cm for women
• Two or more risk factors
43
Approach to Obesity at Clinical level
• A full history with a dietary inventory and an analysis
of the subject's activity level.
• Screening questions to exclude depression
• Screening for eating disorders as 30% of patients
suffer from them
• Determine any co-morbidities;
• Exclude the possible and rare secondary causes
• Requirements of treatment and belief to fulfill
• Behavior assessment for readiness
• Family support, time and financial considerations
Approach at community level
•
•
•
•
•
•
•
•
•
Empowering parents, and caregivers
Healthy foods in schools & restaurants
Access to healthy affordable food
Avenues for physical activity (www.letsmove.gov)
Safe neighborhoods; playgrounds, parks
Physical education in schools/child care facilities
Encourage breast feeding
Farmers markets; local fruits and vegetables available
Any barriers considered
Keeping a watch on public messages
Grains, Vegetables, Fruits, Milk/Dairy, Meat & Beans
& oils
Steps to follow at individual level
•
•
•
•
•
•
•
•
•
Cutting Back on Salt and Sodium
Be a Healthy Role Model for Children
Following a Vegetarian Diet
Going Green with My Pyramid
Choose a Harvest of Colorful Vegetables
Make Half Your Grains Whole
Focus on Fruits
Cut Back on Sweet Treats
Brisk walk 3 times/day for 10 minutes ; 5 days/wk
Conclusion
• Obesity is a substantial public-health crisis
• The prevalence is increasing rapidly in
numerous developing nations worldwide;
including Saudi Arabia
• This growing rate represents a pandemic that
needs urgent attention; potential for morbidity,
mortality, and economic tolls.