1. Obesity: Pathophysiology, Risk Assessment, and Prevalence

2. Obesity Excessive amount of body fat Women with > 35% body fat
Increased risk for health problems
Are usually overweight, but can have healthy BMI and high % fat
Measurements using calipers

3. Desirable % Body Fat
Men: 8-25%
Women 20-35%

4. Regional Distribution
The regional distribution of body fat affects risk factors for the heart disease and type 2 diabetes

5. Body Fat Distribution: Gynecoid
Lower-body obesity--Pear shape
Encouraged by estrogen and progesterone
Less health risk than upper-body obesity
After menopause, upper-body obesity appears

6. Body Fat Distribution: Android
Upper-body obesity--apple shape
Associated with more heart disease, HTN, Type II Diabetes
Abdominal fat is released right into the liver
Encouraged by testosterone and excessive alcohol intake
Defined as waist measurement of > 40” for men and >35” for women

7. Body Fat Distribution

8. Weight Management
Balancing energy intake and energy expenditure is the basis of weight management throughout life

9. Set Point Theory Body tends to preserve a given weight
Energy expenditure increases and decreases with weight loss and gain
Effect may be temporary, e.g. energy needs drop during calorie restriction and normalize when energy balance is achieved

10. Components of Energy Expenditure
Resting energy expenditure: expressed as RMR
Energy expended in voluntary activity
Thermic effect of food (TEF) or diet-induced thermogenesis (DIT)
Related to energy value of food consumed and adaptive response to overeating
TEF may decline as day progresses (Romon, AJCN, 1993)

11. Resting Metabolic Rate
Increases with increased muscle mass
Declines with age
Declines during restriction of energy intake (up to 15%)
Explains 60-70% of total energy expenditure

12. Voluntary Energy Expenditure (activity thermogenesis)
The most variable component of energy expenditure
Accounts for 15-30% of total
Most of us will require increasing voluntary energy expenditure as we age to offset declining fat free mass and RMR in order to maintain weight

13. Role of Brain Neurotransmitters
Neurotransmitters govern the body’s response to starvation and dietary intake
Decreases in serotonin and increases in neuropeptide Y are associated with an increase in carbohydrate appetite
Neuropeptide Y increases during deprivation; may account for increase in appetite after dieting
Cravings for sweet high-fat foods among obese and bulimic patients may involve the endorphin system

14. Hormonal Regulation of Body Weight
Norepinephrine and dopamine—released by sympathetic nervous system in response to dietary intake
Fasting and semistarvation lead to decreased levels of these neurotransmitters—more epinephrine is made and substrate is mobilized.

15. Hormones and Weight Hypothyroidism may diminish adaptive thermogenesis
Insulin resistance may impair adaptive thermogenesis
Leptin is secreted in proportion to percent adipose tissue and may regulate (decrease) appetite

16. Hunger vs. Satiety
Satiety—postprandial state when excess food is being stored
Hunger—postabsorptive state when stores are being mobilized
Short-term regulation affected

17. Hunger vs. Satiety—cont’d
Feedback mechanism with signal from adipose mass when weight loss occurs—eating is the natural result
Not always identified in the elderly
This occurs mostly in young people
Long-term regulation affected

18. Nature vs Nurture Identical twins raised apart have similar weights
Genetics account for ~40%-70% of weight differences
Genes affect metabolic rate, fuel use, brain chemistry, body shape
Thrifty metabolism gene allows for more fat storage to protect against famine

19. Nature vs Nurture Obesity tends to run in families
If both parents are normal weight – 10% chance of obesity in offspring
If one parent is obese – 40% chance
If both parents obese – 80% chance
Is it genetics or learned eating behavior?

20. Nurture vs Nature Environmental factors influence weight
Learned eating habits
Activity factor (or lack of)
Poverty and obesity
Female obesity is rooted in childhood obesity
Male obesity appears after age 30

21. Nurture vs Nature Overeating learned early in childhood
Bottle vs breast
Urging children to eat more, clean their plates
Use of food as a reward

22. Food = Love
Shelly Thorene Photography

23. Nature and Nurture
Obesity is nurture allowing nature to express itself
Location of fat is influenced by genetics
A child of obese parents must always be concerned about his weight

24. Nature and Nurture
The influence of environment is apparent in the fact that the prevalence of obesity has increased dramatically in the US in the past 40 years

25. Causes of Obesity

26. Causes of Excessive Energy Intake
Active: large portion sizes, frequent meals and snacks
Passive: excessive intake of energy-dense foods containing hidden calories
Variety of options: the greater the variety of foods offered, the greater the intake
Sensory-specific satiety: as foods are consumed they become less appealing

27. Low Energy Expenditure
There is a mismatch between our thrifty metabolic genetic heritage and the sedentary American lifestyle

28. Obesity is a Growing Problem
127 million adults in the U.S. are overweight, 60 million obese, and 9 million severely obese.
66 percent of U.S. adults are overweight (BMI≥25)
32 percent are obese (BMI≥30)
17% of children and adolescents ages 2-19 are overweight

29. Obesity Trends* Among U.S. Adults BRFSS

30. Prevalence of Obesity in Ohio

31. Obesity: A Major Health Issue
Obesity is the No. 2 preventable cause of death and disability (smoking is #1)
Obesity is associated with increased risk of heart disease, stroke, gallbladder disease, cancer, osteoarthritis, sleep apnea
Obesity-related health problems cost $75 billion annually (2003 data)
The public pays about $39 billion a year -- or about $175 per person -- for obesity through Medicare and Medicaid programs

32. Health Problems Associated with Excess Body Fat
Surgical risk
Lung (pulmonary) disease
Sleep apnea
HTN
CVD
Bone and joint disorders (gout, osteoarthritis)
Type 2 diabetes
Gallstones
Cancers (breast, colon, pancreas, gallbladder)
Infertility
Pregnancy- difficult delivery
Reduced agility
Early death

33. NHANES III Prevalence of Hypertension* According to BMI
Percent
Data from NHANES III show that the prevalence of high blood pressure increases progressively with higher levels of BMI in men and women.
The prevalence of high blood pressure in adults with BMI >30 is 41.9 percent for men and percent for women, respectively, compared with 14.9 percent for men and 15.2 percent for women with BMI 25.
Other studies, such as the large international Intersalt study, carried out in more than 10,000 men and women also reported a 10 kg (22 lb) higher body weight to be associated with a 3 mm Hg systolic and 2.3 mm Hg diastolic change in blood pressure.
These differences in blood pressure, as shown in the Intersalt study, translate into a 12 percent increased risk for CHD and 24 percent increased risk for stroke.
*Defined as mean systolic blood pressure 140 mm Hg, mean diastolic 90 mm Hg, or currently taking antihypertensive medication.
Brown C et al. Body Mass Index and the Prevalence of
Hypertension and Dyslipidemia. Obes Res. 2000;8:

34. Obesity and Diabetes Risk
Incidence of New Cases per 1,000 Person-Years
In a study of Pima Indians by Knowler and colleagues, the contributions of obesity to the incidence of diabetes and parental diabetes were examined.
The incidence of diabetes mellitus was determined in 3,137 Pima Indians during periodic examinations that included measurement of weight, height, and glucose tolerance.
Data was adjusted for age and sex. The incidence was strongly related to body mass index, increasing steadily from 0.8 ± 0.8 cases/1000 person-years in subjects with body mass index < 20 kg/m2 to cases/1000 person-years in those with body mass index > 40 kg/m2 (reported as rate + standard error). Obesity was strongly related to the incidence of diabetes over the entire range of BMI.
BMI Levels
Knowler WC et al. Am J Epidemiol 1981;113:

35. Weight Gain and Diabetes Risk
Weight Change Since Age 21
Relative Risk
The objective of this prospective study by Chan and colleagues was to investigate the relationship between obesity, fat distribution, and weight gain through adulthood and the risk of non-insulin-dependent diabetes mellitus (NIDDM).
In 1986, baseline data were collected from 27,983 U.S. male health professionals, 40 to 75 years of age. Current height and weight, medical history, past and frequent smoking habits, family history of various diseases, and weight at age 21 were collected. Biennial questionnaires sent out in 1988, 1990, and 1992 were used to update exposure information and ascertain newly diagnosed cases of diabetes.
Multivariate analysis was calculated to control for smoking, family history of diabetes, and age. There was a strong positive association between overall obesity as measured by body mass index (BMI) and risk of diabetes.
Early obesity strongly predicts the risk of diabetes. As shown in this slide, overall absolute weight gain throughout adulthood was strongly related to risk of diabetes, regardless of BMI at age 21. Risk increased within each tertile of weight gain as well as within each category of BMI at age 21. Clearly, those who began with higher BMI (> 24kg/m2) and gained substantial weight (> 11.0 kg) had the highest RR (RR = 21.1, 95% CI 8.5–52.3).
The steady increase in change in weight gain shows that almost any weight gain after adolescence is associated with a higher risk of diabetes. These data suggest that it may be equally important to attain a healthy weight earlier in life as well as maintain it throughout adulthood.
Body Mass Index at Age 21
Adapted from Chan JM et al. Diabetes Care 1994;17:

36. Metabolic Syndrome Criteria*
Three or more of the following abnormalities:
Waist circumference >102 cm (40 inches) in men and > 88 cm (35 inches) in women
Serum triglycerides of at least 150 mg/dL
High density lipoprotein level <40 mg/dL in men and <50 mg/dL in women
Blood pressure >=135/85 mm/hg
Serum glucose >=110 mg/dl
Includes 47 million US residents (27.7% of the population
*ATP III Guidelines. National Cholesterol Education Program, 2001

37. Polycystic Ovary Syndrome (PCOS)
Endocrine disorder characterized by hyperandrogenism and insulin resistance
Associated with android obesity
Affects 5-10% of reproductive age women
Erratic menstrual periods, chronic anovulations resulting in multiple ovarian cysts; infertility, acne, hirsutism and alopecia
Increased risk of heart disease, type 2 diabetes, reproductive cancers

38. Management of PCOS Symptom oriented, as etiology is unclear
Individualized diet and exercise plan to promote weight loss and normalize insulin levels
Medications to alleviate symptoms

39. 26 -Year Incidence of Coronary Heart Disease in Men
Obesity as an independent risk factor for cardiovascular disease was reexamined by Helen Hubert in the 5,209 men and women of the original Framingham cohort. Observations of disease occurrence over the 26 years indicate that obesity was an independent predictor of CVD, particularly among the younger members of the cohort and in women more than men.
This study also showed that weight gain after the young adult years conveyed an increased risk of CVD in both sexes that could not be attributed to the initial weight or the levels of the risk factors that may have resulted from the weight gain.
This slide shows the increasing incidence of coronary heart disease with increasing body mass index levels for both age groups of men. However, the gradient of risk was steeper among the younger men and women (< 50 years) . Among men younger than 50 years, the heaviest group experienced twice the risk of coronary disease compared with the leanest group.
BMI Levels
Adapted from Hubert HB et al. Circulation 1983;67:
Metropolitan Relative Weight of 110 is a BMI of approximately 25.

40. 26 -Year Incidence of Coronary Heart Disease in Women
In women, the incidence of coronary heart disease increased with increasing body mass index levels for both age groups.
Among women older than 50 years, the heaviest group experienced 292 incidents of coronary heart disease compared with 223 in the BMI group < 25.
In women younger than 50 years of age, the group of 30+ BMI experienced 179 incidents compared with only 76 in the < 25 BMI category.
BMI Levels
Adapted from Hubert HB et al. Circulation 1983;67:
Metropolitan Relative Weight of 110 is a BMI of approximately 25.

41. Hypertension Percentage60 50 40
Percentage 30 20
Data in the next 8 slides show results of a population-based longitudinal study by Brown and colleagues. The Australian Longitudinal Study on Women’s Health enrolled 13,431 women who participated in a baseline survey of selected indicators of health and well-being for middle-aged women, age The study explored the associations between body mass index and selected indicators of health and well-being; surgical procedures(cholescystectomy, hysterectomy), symptoms like back pain, and number of visits to general practitioners or specialists. BMI was calculated using self-reported height and weight, corrected following the method of Waters. Hypertension shows a strong monotonic relationship with BMI.
Trend curve estimates the relationship between BMI and hypertension. The percentage of reported hypertension increases with increasing body mass index.
The prevalence of hypertension at different levels of BMI were 10.6%(BMI <20), 13.3% (BMI>20<25), 22.8%(BMI>30<40), and 61.3%(BMI>40).
There was a 6-fold increase in the odds ratio of hypertension between women with BMI<20 and women with BMI >40. 10 20 25 30 35 40
BMI
Relationship between BMI and crude percentage of women reporting
medical problems, surgical procedures, symptoms, and health care utilization.
Brown WJ et al. Int J Obes 1998;22:

42. Diabetes Percentage BMI15 10
Percentage 5
Diabetes, as described in the study by Brown and colleagues of Australian women , shows a monotonic relationship with BMI.
The prevalence of diabetes increases 6-fold between women with a BMI < 20 and women with a BMI > 40.
Most of the increase in diabetes prevalence occurs in women with BMI >30. Prevalence is 1.6% at BMI < 20, 1.4% at BMI > 20-< 25, 3.2% at BMI > 25-< 30, 5.9% at BMI > 30-< 40, and 19.3% at BMI > 40.
There is a 16-fold increase in the odds ratio for diabetes between women with BMI < 20 and women with BMI > 40. 20 25 30 35 40
BMI
Relationship between BMI and crude percentage of women reporting
medical problems, surgical procedures, symptoms, and health care utilization.
Brown WJ et al. Int J Obes 1998;22:

43. Cholescystectomy Percentage BMI25 20
Percentage 15 10 5
In the study by Brown and colleagues, the relationship between BMI and cholescystectomy also shows an upward trend with increasing BMI.
A linear increase of increasing surgical procedures is seen for cholescystectomy as BMI increases.
There is a 7-fold increase in the odds ratio of cholescystectomy in women with a BMI of < 20 compared to women with a BMI of > 40. 20 25 30 35 40
BMI
Relationship between BMI and crude percentage of women reporting
medical problems, surgical procedures, symptoms, and health care utilization.
Brown WJ et al. Int J Obes 1998;22:

44. Back Pain 35 30
Percentage 25 20
Back pain is described in the study by Brown and colleagues as increasing with higher BMI. This trend curve shows the relationship between BMI and back pain.
There is a 40% increase in the odds ratio of back pain between women with BMI < 20 and women with BMI > 40.
Back pain is one of the most common symptoms reported by women in studies of health concerns. 15 20 25 30 35 40
BMI
Relationship between BMI and crude percentage of women reporting
medical problems, surgical procedures, symptoms, and health care utilization.
Brown WJ et al. Int J Obes 1998;22:

45. Body Mass Index and Mortality Risk
(Adapted from Bray GA. Gray DS, Obesity, part 1: Pathogenesis. West J Med 149:429, 1988; and Lew EA, Garfinkle L; Variations in mortality by weight among 750,000 men and women. J Clin Epidemiol 32:563, 1979.)

46. BMI and Health Below 18.5 Underweight 18.5 – 24.9 Normal 25.0 – 29.9
Overweight
Monitor for risk
30.0 and Above
Obese
Increased health risk
40.0 and above
Severely obese
Major health risk