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Obesity Presented by Kristen Billings What is Obesity? Surplus of adipose tissue-containing fat stored in triglyceride form Characterized by excess body weight Overweight is defined as deviation in body weight from some standard or “ideal” weight related to height. Body weight is a function of energy balance over an extended period of time Overweight does not always reflect obesity The point at which excessive fat constitutes obesity is arbitrary Epidemiology Accessible, abundant, and inexpensive energy-dense foods among industrialized countries Substantial reduction in average daily energy expenditure required for survival. Evolutionary adaptation theory More than two decades of steadily increasing rates of obesity Since the end of 2006 the rates have appeared to stabilize Epidemiology 66% are overweight, 5% extremely obese 18% of children are overweight In 2006- 33.3% of adult men and 35.3% women in U.S were categorized as obese (BMI > 30) Notably higher raters of obesity were seen in Hispanic and non-Hispanic black women. Cost Obesity related conditions account for 7% of total healthcare costs in the U.S. Direct and indirect costs of obesity are in excess of $117 billion annually Symptoms BMI (weight in kg/height squared in meters): Class I 30.0-34.9 Class II 35.0-39.9 Class III >40.0 Excessive accumulation of body fat Women >35% Men >25% Diagnosis Body Mass Index Waist Circumference Body Fat Percentages Waist to hip ratio Complications Associated with numerous comorbidities, many of which are life threatening Increases the overall risk and severity of numerous diseases Altered physiological responses: increased fasting insulin, increased insulin response to glucose, decreased insulin sensitivity, decreased growth hormone, decreased growth hormone response to insulin stimulation, increased adrenocortical hormones, increased cholesterol synthesis and excretion, decreased hormone-sensitive lipase Complications Distribution of fat is of more importance for risk of disease than total fat alone Upper body fat distribution (android obesity): strongly correlated with increased risk of coronary artery disease, hypertension, hyperlipidemia, diabetes, hormone and menstrual dysfunction Complications Chronic Diseases Diabetes Hypertension Hypercholesterolemia Hyperinsulinemia Hypertriglyceridemia Increased risk of cardiovascular disease Treatment Primary objective of obesity management is to reduce fat weight while preserving lean body weight Behavioral change focused on dietary and activity habits toward weight reduction FDA approved drugs FDA approved invasive procedures Treatment- Behavioral Change Patients are less motivated by health and more by personal appearance Success in weight loss is more commonly seen when: Person is slightly or moderately obese Has upper body fat distribution Doesn’t have a history of weight cycling Sincere desire to lose weight Became overweight as an adult Treatment- Drugs Drug Mechanism of action Exercise-related precautions Adipex-P Appetite suppressant Increase in blood pressure Meridia Appetite suppressant Increase in blood pressure Dexedrine CNS stimulant Possible cardiovascular risks Alli & Xenical Reduction in fat absorption via inhibition of pancreatic lipase activity in intestine none Treatment- Invasive Procedures Based on reducing the size of stomach and lowering the absorption of nutrients in the intestine Must have BMI of >40 or >35 with comorbidities such as diabetes and hypertension to be eligible Surgical treatment of obesity has been shown to reduce excess body weight by an average of 50-60% Treatment- Invasive Procedures Laparoscopic gastric banding Minimally invasive surgery Adjustable silicone band is placed around top portion of stomach Small gastric pouch is created which reduces capacity of stomach and produces a feeling of fullness shortly after eating Benefits: minimal surgical trauma and pain, fast recovery rate, rare operative mortality. Surgery Videos http://www.youtube.com/watch?v=n-ucSHx9nHM http://www.youtube.com/watch?v=P83Vs9GQ0WI Treatment- Invasive Procedures Roux-en-Y gastric bypass Invasive surgical procedure that reduces capacity of the stomach A small pouch is created at the top of the stomach that is then connected directly to middle portion of the small intestine The rest of the stomach and the upper portion of the small intestine are bypassed. Procedure has a higher mortality and complication risk than the lap-band Effects of Exercise Biomechanical Effects Excess joint stress Affected movement and gait Increased foot pressure Decreased strength Increased risk of osteoarthritis http://www.youtube.com/watch?v=cNATWsVVwgo Effects of Exercise Comorbidities of obesity (diabetes, hypertension, CAD, sleep apnea, increased overall risk of exercise) may affect the exercise response. Past experiences/current fears of exercise Exercise training in combination with caloric restriction reduces body weight and favorably alters body composition. Ineffective in morbidly obese individuals Benefits of Exercise Preservation of lean body mass despite caloric restriction Improved insulin sensitivity Favorable changes in metabolic rate and lipid profiles Reduced blood pressure Improved mood Possible effects on satiety Overall reduction in comorbidity risk Benefits of Exercise Loss of regional fat More effective in reducing abdominal fat cell size than diet alone Energy expenditure following exercise remains elevated above pre-exercise levels Glucose metabolism Decreased fasting glucose and insulin Increased glucose tolerance Decreased insulin resistance Exercise Testing Primary goal: develop a safe and effective exercise program Low-level protocols are recommended because of the low function capacity of most obese individuals Testing protocol must take into consideration any comorbidities, orthopedic limitations and current medications. Arm or leg ergometry may be more appropriate depending on orthopedic limitations and weight limits of treadmills. Exercise Testing Initial exercise intensity is most likely far below the point at which cardiac risk is of concern Exercise testing is used to determine physical work capacity Special Considerations Increased risk of orthopedic injury Physical injury may be primary reason for discontinuation of exercise Increased risk of cardiovascular disease Increased risk of heat intolerance Weight regain averages 33-50% of initial weight loss within 1 year of terminating treatment Exercise Prescription Exercise prescription should optimize energy expenditure while maintaining minimal potential for injury Total energy expenditure should include that of the actual exercise as well as the recovery period Two or more short sessions/day may be more tolerable and result in same or higher total energy expenditure Exercise Prescription ACSM recommends accumulating 200-300 min/week (>2000 kcal/week) of physical activity for weight loss and weight maintenance. Initial intensity and duration should be low and progression should be gradual: Mode- non-weight-bearing exercise such as: walking, swimming, biking increase in activities of daily living and resistance training Frequency-daily or at least 5/week Duration- 200-300 min/wk (30-60 min/day) Intensity- 40-60% of peak oxygen consumption Exercise Goals Significant health benefits can be achieved by losing only 10-20% of body weight even if the ideal body weight is not reached Loss of 1lb/week, -3500 calories/week, -500 calories/day Loss of 10lbs maintained for 6 months before further weight loss Summary and Conclusion Overuse injury prevention Adequate flexibility, warm-up, cool-down Gradual progression of intensity and duration Use of low-impact or non-weight-bearing exercises Thermoregulation Neutral temperature and humidity Cool times of day Adequate hydration Loose fitting clothing References 1.American College of Sports Medicine. 2010. ACSM’s guidelines for exercise testing and prescription, 8th ed. Baltimore: Lippincott Williams & Wilkens, chapter 10. 2.ACSM. 1999. Roundtable Supplement. Physical activity in the prevention and treatment of obesity and its comorbitities. Med. Sci. Sport Exer. 31(11) : S497-S667. 3. American Obesity Association. 2000. http://www.obesity.org/ 4.ACSM. 2009. Position Stand. Appropriate physical activity intervention strategies for weight loss and prevention of weight gain for adults. Med. Sci. Sport Exer. 41 :459-467. 5.Rampersaud, E., et al. 2008. Physical activity and the association of the common FTO gene variants with body mass index and obesity. Arch Intern Med. 168(160): 1791-1797. 6. Patricia Curtis. 2007. Fighting Fat New Frontiers. Readers Digest. 85-91
