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الخاصة السورية الجامعةالبشري الطب كلية

المجتمع طب قسم

ObesityM.A.Kubtan MD - FRCS

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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.

Key Points

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   Gender Differences   Race and Ethnic Origin   Socioeconomic Status   Education Level   Rural and Urban Differences   Age 

Demographics

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Determinants of Obesity 

Genetics vs. Lifestyle  Lifestyle Influences  Endocrine and Metabolic Factors 

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Body mass index can be calculated as : wt (kg)/ht2 (m) .

Body mass index (BMI)

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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,

The problem of obesity

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Workers with BMI over 35 kg/m2 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 .

Continue

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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

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BMI . Body fat percentage : is a precise

assessment of adiposity

Assessment

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Health risks increase above a waist circumference of 35 inches in women and 40 inches in men

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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.

Demographics

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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.

Gender Differences

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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.

Socioeconomic Status

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Education level is inversely related to the risk of obesity .

Education Level

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Analysis data shows that the prevalence of obesity is greater in rural than urban areas.

Factors that reduce physical activity may play a role .

Rural and Urban Differences

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The increased prevalence of overweight is alarming in the pediatric population .

More than 30% of children and adolescents are overweight or obese.

Age

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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.

Determinants of Obesity Genetic Factors

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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.

Determinants of ObesityModern Life Factors

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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.

Lifestyle Influences

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More than 250 genes and chromosomal regions are associated with phenotypic obesity .

The genes code specifically for visceral as opposed to subcutaneous obesity.

Impact of Genetic Factors

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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 .

Humeral Factors affecting Obesity

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Melanocortin 4 receptor (MC4R) 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 genotype-phenotype correlations

Probable role of Melanocortin

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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.

Modulation of Appetite

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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.

Endocrine and Metabolic Factors