Key Points Body mass index BMI determines the

Key Points � Body mass index (BMI) determines the classification of obesity for clinical use. � Waist circumference reflects the distribution of adipose tissue and helps determine obesity risk. � Central obesity, reflected by a high waist measurement, is associated with more complications. M. A. Kubtan 2

Demographics � Gender Differences � Race and Ethnic Origin � Socioeconomic Status � Education Level � Rural and Urban Differences � Age M. A. Kubtan 3

Determinants of Obesity � Genetics vs. Lifestyle � Lifestyle Influences � Endocrine and Metabolic Factors M. A. Kubtan 4

Body mass index (BMI) Ø Body mass index can be calculated as : wt (kg)/ht 2 (m). M. A. Kubtan 5

The problem of obesity Globally, overnutrition has now surpassed undernutrition as a public health concern � 8. 5% of the world population is overweight � 5. 8% underweight � 2. 3 billion adults will be overweight and 700, 000 million obese by 2015. � Persons in the overweight category have 20% to 40% increased mortality, � M. A. Kubtan 6

Continue � Workers with BMI over 35 kg/m 2 experienced a 4. 2% health-related drop in productivity � The medical consequences of obesity have been estimated to account for 9. 1% of annual medical spending. M. A. Kubtan 7

M. A. Kubtan 8

M. A. Kubtan 9

Surveys from 1976– 1980 and 2003– 2006 found that : � Obesity increased from 5. 0% to 12. 4% among children age 2 to 5 years; � From 6. 5% to 17. 0% for ages 6 to 11 years; � From 5. 0% to 17. 6% for ages 12 to 19 years. Changes in obesity prevalence have affected all U. S. regions M. A. Kubtan 10

Assessment � BMI . � Body fat percentage : is a precise assessment of adiposity M. A. Kubtan 11

Health risks increase above a waist circumference of 35 inches in women and 40 inches in men M. A. Kubtan 12

Demographics � Men are more likely than women to have central obesity. � African Americans, Hispanics, and Native Americans are at greater risk of obesity than whites. � Obesity is inversely related to education and socioeconomic status. � Obesity is more prevalent in rural than urban areas. M. A. Kubtan 13

Gender Differences � Men are more likely than women to be overweight. � Women are more likely to be obese. � Men, however, are more likely to have central obesity, associated with greater health risks. M. A. Kubtan 14

Socioeconomic Status � The prevalence ranges from approximately 2% in the least developed countries to over 30% in the most developed countries. � In developed countries, lower socioeconomic status is associated with an increased risk. M. A. Kubtan 15

Education Level � Education level is inversely related to the risk of obesity. M. A. Kubtan 16

Rural and Urban Differences � Analysis data shows that the prevalence of obesity is greater in rural than urban areas. � Factors that reduce physical activity may play a role. M. A. Kubtan 17

Age � The increased prevalence of overweight is alarming in the pediatric population. � More than 30% of children and adolescents are overweight or obese. M. A. Kubtan 18

Determinants of Obesity Genetic Factors � Obesity results from the interaction of genetic makeup, environment, and lifestyle. � Genetic factors are estimated to account for 30% to 40% of the variability in adult weight. � Overall, genetic factors are estimated to be responsible for 30% to 40% of the variability in adult weight. � Specific metabolic or endocrine disorders account for less than 1% of the obese population. M. A. Kubtan 19

Determinants of Obesity Modern Life Factors � Obesity results from calorie consumption in excess of expenditure. � The conveniences of modern life have led to a decrease in energy expenditure. � A greater access to energy-dense food, along with other factors, has increased energy consumption. M. A. Kubtan 20

Lifestyle Influences � Increased caloric intake is related in part to eating away from home. � Smoking cessation is associated with weight gain of 4 to 5 kg (on average). � Many antidepressants, neuroleptics, and anticonvulsants are associated with weight gain. � Decreased overall physical activity (not just “exercise”) is a major factor associated with the increasing prevalence of overweight and obesity. M. A. Kubtan 21

Impact of Genetic Factors � More than 250 genes and chromosomal regions are associated with phenotypic obesity. � The genes code specifically for visceral as opposed to subcutaneous obesity. M. A. Kubtan 22

Humeral Factors affecting Obesity � Leptin is a protein produced in adipose tissue that provides negative feedback to appetite control centers. � Ghrelin, a peptide produced in the stomach and duodenum that stimulates eating. � Defects in melanocortin receptors in the adrenals have also been associated with obesity. � FTO (fat mass and obesity-associated) gene. M. A. Kubtan 23

Probable role of Melanocortin � Melanocortin 4 receptor (MC 4 R) deficiency is the commonest monogenic form of obesity. However, the clinical spectrum and mode of inheritance have not been defined, pathophysiological mechanisms leading to obesity are poorly understood, and there is little information regarding genotypephenotype correlations M. A. Kubtan 24

Modulation of Appetite � Leptin levels. � Vagal afferent activity. � Fluctuation in plasma glucose levels. � Neuropeptides and monoamine neurotransmitters are also involved in appetite control. � Some weight loss medications may affect appetite or satiety. M. A. Kubtan 25

Endocrine and Metabolic Factors � Hypothyroidism is a relatively rare cause of obesity. � Neuroendocrine Factors � Cushing’s Syndrome is associated with central obesity and “buffalo hump” along with axillary striae, glucose intolerance and hypertension. � Polycystic Ovary Syndrome , menstrual irregularities , hirsutism, elevated testosterone and luteinizing hormone blood levels , Insulin resistance is a consistent finding. � Growth Hormone Deficiency , impaired in growth hormone deficiency, there is an increase in truncal obesity. M. A. Kubtan 26