Obesity in US
-overweight or obese is norm in US
-overweight and obesity 66% and rising
Weight Key Concepts
-"ideal" weight and shape defined by culture, HEALTH
-rate of overweight/obese increasing worldwide
-disease and disorders related to body fat also increasing
-location and amount of body fat stores important to health
Influences on Development of Obesity/Overweight
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Body Weight Variations
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Body Mass Index
-measure of weight for height to estimate body fat
-ranges of BMI define weights for height:
~underweight, <18.5 kg/m2
~normal, 18.5-24.9
~overweight, 25-29.9
~obese, >30
-BMI calculations same for males and females: [weight (lbs) x 703/height (in)]2 OR [weight (kg) / height (m)]2
Metabolic Abnormalities
-70% of obese people have metabolic abnormalities that increase disease risk of: hypertension; elevated triglycerides, glucose or insulin; low HDL-cholesterol (good); high C-reactive protein (inflammation marker)
-10-15% weight loss decreases risks
Health Risks associated with Obesity and Overweight
-hypertension
-type 2 diabetes
-coronary heart disease
-gallbladder disease
-certain cancers
-dyslipidemia (elevated cholesterol, triglycerides, etc)
-stroke
-osteoarthritis
-sleep apnea
-deep vein thrombosis
-reproductive disorders
BMI Percentiles, Ages 2-20
-body fat, not BMI percentiles should be used to diagnose obesity in children and adolescents
-underweight: 5th percentile range or less
-at risk for underweight: 5-15th
-normal: 15-85th
-at risk for overweight: 85-95th
-overweight: 95th or higher
Obesity and Health
-not a healthy state
-increased risk for: diabetes, hypertension, stroke, heart disease, elevated total cholesterol levels, low HDL cholesterol levels, certain types of cancers, other health problems
-life expectancy in overweight/obese adults is 3-6 years shorter than average
-weight loss lowers blood pressure, LDL cholesterol, risk of diabetes and increases HDL cholesterol
Body Fat Content
-weight-for-height and percent body fat don't always correspond
-muscular people can have "obese" BMI
-inactive normal BMI people can still have too much body fat
-if people retain fluid, BMI may show overweight but body fat may be low
-measures of body fat are more accurate than weight-for-height
Body Fat and Health
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Risk of Abdominal (visceral) Body Fat
-fat cells of central fat deposits are larger than those around the hips and are "resistant" to insulin
-decrease ability of insulin to lower blood glucose
-insulin and glucose increase over time
-increased insulin: increases triglyceride levels and BP, reduces levels of HDL cholesterol, increases hypertension and risk of heart disease, promotes development of diabetes, metabolic syndrome
Metabolic Syndrome
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Body Fat Distribution
-waist size is stronger predictor of heart disease, stroke and diabetes than BMI
-waist <40 inches in men or <35 inches in women decreases risk of these diseases
Assessment of Body Fat Content
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Necessary Body Fat
-3 to 5% for men and 10 to 12% for women needed for survival
-body fat essential in manufacture of hormones
-required component of every cell in body
-low body fat levels: delayed physical maturation during adolescence, infertility, accelerated bone loss, problems that accompany starvation
Body Fat Percentage
-LOW
~women: less than 12%
~men: less than 5%
-Average
~women: 32%
~men: 22%
-High
~35% or more
~25% or more
Preventing Obesity
-major gains most likely between the ages of 25 and 34
Underweight
-worldwide, underweight is more common than obesity
-preventable cause of underweight in US is poverty
underweight: less than 20% body fat in adult females and 8% body fat in males
-defined as BMI below 18.5 kg/m2