Weight Management: Risk and Pathophysiology


Published on

  • Be the first to comment

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide
  • 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 37.8 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.
  • 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/m 2 to 72.2 + 14.5 cases/1000 person-years in those with body mass index > 40 kg/m 2 (reported as rate + standard error). Obesity was strongly related to the incidence of diabetes over the entire range of BMI.
  • 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/m 2) 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.
  • 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.
  • 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.
  • 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 45-49. 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.
  • 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.
  • 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.
  • 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.
  • Weight Management: Risk and Pathophysiology

    1. 1. Obesity: Pathophysiology, Risk Assessment, and Prevalence
    2. 2. Obesity <ul><li>Excessive amount of body fat </li></ul><ul><ul><li>Women with > 35% body fat </li></ul></ul><ul><ul><li>Men with > 25% body fat </li></ul></ul><ul><li>Increased risk for health problems </li></ul><ul><li>Are usually overweight, but can have healthy BMI and high % fat </li></ul><ul><li>Measurements using calipers </li></ul>
    3. 3. Desirable % Body Fat <ul><li>Men: 8-25% </li></ul><ul><li>Women 20-35% </li></ul>
    4. 4. Regional Distribution <ul><li>The regional distribution of body fat affects risk factors for the heart disease and type 2 diabetes </li></ul>
    5. 5. Body Fat Distribution: Gynecoid <ul><li>Lower-body obesity--Pear shape </li></ul><ul><li>Encouraged by estrogen and progesterone </li></ul><ul><li>Less health risk than upper-body obesity </li></ul><ul><li>After menopause, upper-body obesity appears </li></ul>
    6. 6. Body Fat Distribution: Android <ul><li>Upper-body obesity--apple shape </li></ul><ul><li>Associated with more heart disease, HTN, Type II Diabetes </li></ul><ul><li>Abdominal fat is released right into the liver </li></ul><ul><li>Encouraged by testosterone and excessive alcohol intake </li></ul><ul><li>Defined as waist measurement of > 40” for men and >35” for women </li></ul>
    7. 7. Body Fat Distribution
    8. 8. Weight Management <ul><li>Balancing energy intake and energy expenditure is the basis of weight management throughout life </li></ul>
    9. 9. Set Point Theory <ul><li>Body tends to preserve a given weight </li></ul><ul><li>Energy expenditure increases and decreases with weight loss and gain </li></ul><ul><li>Effect may be temporary, e.g. energy needs drop during calorie restriction and normalize when energy balance is achieved </li></ul>
    10. 10. Components of Energy Expenditure <ul><li>Resting energy expenditure: expressed as RMR </li></ul><ul><li>Energy expended in voluntary activity </li></ul><ul><li>Thermic effect of food (TEF) or diet-induced thermogenesis (DIT) </li></ul><ul><ul><li>Related to energy value of food consumed and adaptive response to overeating </li></ul></ul><ul><ul><li>TEF may decline as day progresses (Romon, AJCN, 1993) </li></ul></ul>
    11. 11. Resting Metabolic Rate <ul><li>Increases with increased muscle mass </li></ul><ul><li>Declines with age </li></ul><ul><li>Declines during restriction of energy intake (up to 15%) </li></ul><ul><li>Explains 60-70% of total energy expenditure </li></ul>
    12. 12. Voluntary Energy Expenditure (activity thermogenesis) <ul><li>The most variable component of energy expenditure </li></ul><ul><li>Accounts for 15-30% of total </li></ul><ul><li>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 </li></ul>
    13. 13. Role of Brain Neurotransmitters <ul><li>Neurotransmitters govern the body’s response to starvation and dietary intake </li></ul><ul><li>Decreases in serotonin and increases in neuropeptide Y are associated with an increase in carbohydrate appetite </li></ul><ul><li>Neuropeptide Y increases during deprivation; may account for increase in appetite after dieting </li></ul><ul><li>Cravings for sweet high-fat foods among obese and bulimic patients may involve the endorphin system </li></ul>
    14. 14. Hormonal Regulation of Body Weight <ul><li>Norepinephrine and dopamine—released by sympathetic nervous system in response to dietary intake </li></ul><ul><li>Fasting and semistarvation lead to decreased levels of these neurotransmitters—more epinephrine is made and substrate is mobilized. </li></ul>
    15. 15. Hormones and Weight <ul><li>Hypothyroidism may diminish adaptive thermogenesis </li></ul><ul><li>Insulin resistance may impair adaptive thermogenesis </li></ul><ul><li>Leptin is secreted in proportion to percent adipose tissue and may regulate (decrease) appetite </li></ul>
    16. 16. Hunger vs. Satiety <ul><li>Satiety—postprandial state when excess food is being stored </li></ul><ul><li>Hunger—postabsorptive state when stores are being mobilized </li></ul><ul><li>Short-term regulation affected </li></ul>
    17. 17. Hunger vs. Satiety—cont’d <ul><li>Feedback mechanism with signal from adipose mass when weight loss occurs—eating is the natural result </li></ul><ul><li>Not always identified in the elderly </li></ul><ul><li>This occurs mostly in young people </li></ul><ul><li>Long-term regulation affected </li></ul>
    18. 18. Nature vs Nurture <ul><li>Identical twins raised apart have similar weights </li></ul><ul><li>Genetics account for ~40%-70% of weight differences </li></ul><ul><li>Genes affect metabolic rate, fuel use, brain chemistry, body shape </li></ul><ul><li>Thrifty metabolism gene allows for more fat storage to protect against famine </li></ul>
    19. 19. Nature vs Nurture <ul><li>Obesity tends to run in families </li></ul><ul><li>If both parents are normal weight – 10% chance of obesity in offspring </li></ul><ul><li>If one parent is obese – 40% chance </li></ul><ul><li>If both parents obese – 80% chance </li></ul><ul><li>Is it genetics or learned eating behavior? </li></ul>
    20. 20. Nurture vs Nature <ul><li>Environmental factors influence weight </li></ul><ul><li>Learned eating habits </li></ul><ul><li>Activity factor (or lack of) </li></ul><ul><li>Poverty and obesity </li></ul><ul><li>Female obesity is rooted in childhood obesity </li></ul><ul><li>Male obesity appears after age 30 </li></ul>
    21. 21. Nurture vs Nature <ul><li>Overeating learned early in childhood </li></ul><ul><li>Bottle vs breast </li></ul><ul><li>Urging children to eat more, clean their plates </li></ul><ul><li>Use of food as a reward </li></ul>
    22. 22. Food = Love Shelly Thorene Photography
    23. 23. Nature and Nurture <ul><li>Obesity is nurture allowing nature to express itself </li></ul><ul><li>Location of fat is influenced by genetics </li></ul><ul><li>A child of obese parents must always be concerned about his weight </li></ul>
    24. 24. Nature and Nurture <ul><li>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 </li></ul>
    25. 25. Causes of Obesity
    26. 26. Causes of Excessive Energy Intake <ul><li>Active: large portion sizes, frequent meals and snacks </li></ul><ul><li>Passive: excessive intake of energy-dense foods containing hidden calories </li></ul><ul><li>Variety of options: the greater the variety of foods offered, the greater the intake </li></ul><ul><ul><li>Sensory-specific satiety: as foods are consumed they become less appealing </li></ul></ul>
    27. 27. Low Energy Expenditure <ul><li>There is a mismatch between our thrifty metabolic genetic heritage and the sedentary American lifestyle </li></ul>
    28. 28. Obesity is a Growing Problem <ul><li>127 million adults in the U.S. are overweight, 60 million obese, and 9 million severely obese. </li></ul><ul><li>66 percent of U.S. adults are overweight (BMI ≥ 25) </li></ul><ul><li>32 percent are obese (BMI ≥ 30) </li></ul><ul><li>17% of children and adolescents ages 2-19 are overweight </li></ul>
    29. 29. Obesity Trends* Among U.S. Adults BRFSS
    30. 30. Prevalence of Obesity in Ohio
    31. 31. Obesity: A Major Health Issue <ul><li>Obesity is the No. 2 preventable cause of death and disability (smoking is #1) </li></ul><ul><li>Obesity is associated with increased risk of heart disease, stroke, gallbladder disease, cancer, osteoarthritis, sleep apnea </li></ul><ul><li>Obesity-related health problems cost $75 billion annually (2003 data) </li></ul><ul><li>The public pays about $39 billion a year -- or about $175 per person -- for obesity through Medicare and Medicaid programs </li></ul>
    32. 32. Health Problems Associated with Excess Body Fat <ul><li>Surgical risk </li></ul><ul><li>Lung (pulmonary) disease </li></ul><ul><li>Sleep apnea </li></ul><ul><li>HTN </li></ul><ul><li>CVD </li></ul><ul><li>Bone and joint disorders (gout, osteoarthritis) </li></ul><ul><li>Type 2 diabetes </li></ul><ul><li>Gallstones </li></ul><ul><li>Cancers (breast, colon, pancreas, gallbladder) </li></ul><ul><li>Infertility </li></ul><ul><li>Pregnancy- difficult delivery </li></ul><ul><li>Reduced agility </li></ul><ul><li>Early death </li></ul>
    33. 33. NHANES III Prevalence of Hypertension* According to BMI *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;8:605-619. Percent
    34. 34. Obesity and Diabetes Risk BMI Levels Incidence of New Cases per 1,000 Person-Years Knowler WC et al. Am J Epidemiol 1981;113:144-156.
    35. 35. Weight Gain and Diabetes Risk Body Mass Index at Age 21 Relative Risk Weight Change Since Age 21 Adapted from Chan JM et al. Diabetes Care 1 994;17:960-969.
    36. 36. Metabolic Syndrome Criteria* <ul><li>Three or more of the following abnormalities: </li></ul><ul><li>Waist circumference >102 cm (40 inches) in men and > 88 cm (35 inches) in women </li></ul><ul><li>Serum triglycerides of at least 150 mg/dL </li></ul><ul><li>High density lipoprotein level <40 mg/dL in men and <50 mg/dL in women </li></ul><ul><li>Blood pressure >=135/85 mm/hg </li></ul><ul><li>Serum glucose >=110 mg/dl </li></ul><ul><li>Includes 47 million US residents (27.7% of the population </li></ul>* ATP III Guidelines. National Cholesterol Education Program, 2001
    37. 37. Polycystic Ovary Syndrome (PCOS) <ul><li>Endocrine disorder characterized by hyperandrogenism and insulin resistance </li></ul><ul><li>Associated with android obesity </li></ul><ul><li>Affects 5-10% of reproductive age women </li></ul><ul><li>Erratic menstrual periods, chronic anovulations resulting in multiple ovarian cysts; infertility, acne, hirsutism and alopecia </li></ul><ul><li>Increased risk of heart disease, type 2 diabetes, reproductive cancers </li></ul>
    38. 38. Management of PCOS <ul><li>Symptom oriented, as etiology is unclear </li></ul><ul><li>Individualized diet and exercise plan to promote weight loss and normalize insulin levels </li></ul><ul><li>Medications to alleviate symptoms </li></ul>
    39. 39. 26 -Year Incidence of Coronary Heart Disease in Men Incidence/1,000 BMI Levels Adapted from Hubert HB et al. Circulation 1983;67:968-977. Metropolitan Relative Weight of 110 is a BMI of approximately 25.
    40. 40. 26 -Year Incidence of Coronary Heart Disease in Women Incidence/1,000 BMI Levels Adapted from Hubert HB et al. Circulation 1983;67:968-977. Metropolitan Relative Weight of 110 is a BMI of approximately 25.
    41. 41. Hypertension BMI Percentage 20 25 30 35 40 20 10 30 50 40 60 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;22:520-528.
    42. 42. BMI Percentage 20 25 30 35 40 0 10 5 15 Diabetes Brown WJ et al. Int J Obes 1998;22:520-528 . Relationship between BMI and crude percentage of women reporting medical problems, surgical procedures, symptoms, and health care utilization.
    43. 43. BMI Percentage 20 25 30 35 40 5 10 15 25 20 Cholescystectomy 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;22:520-528.
    44. 44. BMI Percentage 20 25 30 35 40 20 15 30 25 35 Back Pain Brown WJ et al. Int J Obes 1998;22:520-528. Relationship between BMI and crude percentage of women reporting medical problems, surgical procedures, symptoms, and health care utilization.
    45. 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. 46. BMI and Health Severely obese Major health risk 40.0 and above Obese Increased health risk 30.0 and Above Overweight Monitor for risk 25.0 – 29.9 Normal 18.5 – 24.9 Underweight Below 18.5