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Obesity: Pathophysiology, And Risk Assessment

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• Obesity:• Excessive amount of body fat.– Women with > 35% body fat.– Men with > 25% body fat.

• Increased risk for health problems.• Are usually overweight, but can have healthy

Body Mass Index(BMI) and high % fat.• BMI =weight kilograms / height meters2

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

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• Regional Distribution:• The regional distribution of body fat affects

risk factors for the heart disease and type 2 diabetes.

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

appears.

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• Body Fat Distribution: Android• Upper-body obesity--apple shape.• Associated with more heart disease,

Hypertensiion(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.

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• Body Fat Distribution:

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• Weight Management:• Balancing energy intake and

energy expenditure is the basis of weight management throughout life.

• Dieting and physical exercise.• Orlistat (Xenical) medication

to treat obesity.• In severe cases, bariatric

surgery is performed or an intragastric balloon is placed to reduce stomach volume.

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Pathophysiology

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• 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.

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• 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.

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• Hormones And Weight:• Leptin is produced by adipose tissue to signal

fat storage reserves in the body, and mediates long-term appetitive controls (i.e. to eat more when fat storages are low and less when fat storages are high).

• Ghrelin produced by the stomach modulating short-term appetitive control (i.e. to eat when the stomach is empty and to stop when the stomach is stretched)

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• Hunger vs. Satiety:• Satiety—postprandial state when excess food

is being stored.• Hunger—postabsorptive state when stores are

being mobilized.

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• Hunger vs. Satiety—contd:• 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.

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• Causes of Obesity:

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• 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.

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• Low Energy Expenditure:• Sedentary lifestyle.

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• Genetics:• Identical twins have similar weights.• Genes affect metabolic rate, fuel use, brain

chemistry, body shape.• The thrifty gene hypothesis postulates that

due to dietary scarcity during human evolution people are prone to obesity.

• Thrifty metabolism gene allows for more fat storage to protect against famine.

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Genetics: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.

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• Environmental factors influence weight:• Overeating learned early in childhood.• Urging children to eat more, clean their plates.• Use of food as a reward.

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• Medical and psychiatric illness:• Physical and mental illnesses and the

pharmaceutical substances.• Hypothyroidism, Cushing’s syndrome, growth

hormone deficiency, and the eating disorders: Binge eating disorder and Night eating syndrome.

• Insulin, sulfonylureas, thiazolidinediones, atypical antipsychotics, antidepressants, steroids, certain anticonvulsants (phenytoin and valproate), and some hormonal contraception.

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• 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.

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• Obesity: A Major Health Issue:• Obesity is the SECOND 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.

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• 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

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• 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.–*Adult Treatment Panel (ATP) III Guidelines.

National Cholesterol Education Program, 2001.

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• 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.

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• 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.

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• BMI and Health:

Below 18.5 Underweight

18.5 – 24.9 Normal

25.0 – 29.9 OverweightMonitor for risk

30.0 and Above ObeseIncreased health risk

40.0 and above Severely obeseMajor health risk

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• REFERENCE:• Internet: http://medicalppt.blogspot.com• en.wikipedia.org