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Chapter 6 Obesity

Chapter 6 Obesity. Chapter overview. Definition Aetiology Genetic influence Prevalence Health risks Physical inactivity and obesity Exercise as therapy Physical activity recommendations Summary. The questions. How is obesity defined and how does it arise?

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Chapter 6 Obesity

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  1. Chapter 6Obesity

  2. Chapter overview • Definition • Aetiology • Genetic influence • Prevalence • Health risks • Physical inactivity and obesity • Exercise as therapy • Physical activity recommendations • Summary

  3. The questions... • How is obesity defined and how does it arise? • Is there an epidemic of obesity? • If so, are there important risks to the health of the individual and the population? • Does inactivity lead to obesity? • Can physical activity help in the management of obesity?

  4. Criteria for overweight and obesity and waist circumference cut-off points with associated disease risk

  5. Weight loss after prolonged fasting under medical supervision

  6. Influence of weight loss and weight gain on 24-hour energy expenditure

  7. Reduced energy intake and increased expenditure with injection of the satiety hormone oxyntomodulin

  8. Genes are a strong determinant of body fatness – and particularly of visceral fat

  9. BMI values of adopted children are associated with those of their biological parents

  10. Gain in weight and visceral fat in monozygotic twins after overfeeding

  11. Leptin replacement reduced body fatness in three leptin-deficient individuals

  12. Is there an epidemic of obesity?

  13. Increase in BMI in Americans between 1960–2 and 1999–2002

  14. Prevalence of obesity among adults aged 16–64 in England 1986/7–2004

  15. Prevalence of obesity in the year 2002 for adults (aged 15 and over)

  16. Obesity is associated with increased risks to health Note: US data, 1999.

  17. Does inactivity lead to obesity?

  18. Walking or cycling to work is associated with lower risk for obesity

  19. High levels of moderate activityare associated with lower weight gainafter age 45 Note: Activity recorded as MET-h/week over the previous ten years; participants 15,000 US adults aged 53–57.

  20. Low levels of physical activity predispose to weight gain

  21. Physical characteristics, energy expenditure and physical activity levels in Mexican Pima Indians and US Pima Indians

  22. Obese individuals spend more time sitting, and less time standing and moving around Note: Data obtained using accelerometers and inclinometers.

  23. Temporal changes in surrogate measures of physical activity track population changes in obesity prevalence

  24. Can physical activity help in the management of obesity?

  25. Duration of weekly exercise is related to weight loss in overweight and obese women Note: Intake of energy and fat restricted in addition to exercise.

  26. Exercise-induced weight loss is influenced by genetic factors Note: Data from seven pairs of monozygotic twins.

  27. Diet/exercise intervention is associated with loss of subcutaneous and visceral adipose tissue Note: Magnetic resonance images at level of lumbar spine for a man and a woman. Mean weight loss was 11kg over a 16-week intervention.

  28. Drugs licensed for obesity management

  29. Is weight loss in the obese hazardous to health?

  30. Hazard ratios and 95% CIs of total mortality 1982–99 by intention to lose weight in 1975 and weight change 1975–81

  31. Summary I • Obesity is an excess of body fat that endangers health. • It is most commonly determined as BMI of 30kgm2 or over. Elevated waist circumference is another useful marker. • Obesity develops due to an imbalance between energy intake and expenditure. Genes appear to play a major role in determining susceptibility to obesity. • The prevalence of obesity has increased in many countries over the last few decades. • Obesity, particularly severe obesity, increases the risk of premature mortality, type 2 diabetes, CVD, some cancers and osteoarthritis. The extent to which overweight increases these risks is less certain.

  32. Summary II • Observational evidence suggests that physical inactivity is associated with the development of obesity. • Exercise can be effective in the management of obesity, particularly mild obesity. It is most effective when combined with diet. • Weight regain after weight loss is common, but long-term maintenance of weight loss is possible in individuals who maintain healthy dietary and exercise habits. • Recommendations suggest that 45–60 mins/day of exercise is needed to prevent obesity, but 60–90 mins/day to prevent weight regain in formerly obese individuals.

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