Foundations of Physical Activity and Public Health: Overweight and Obesity Notes

Key Concepts

• Obesity as a Public Health Issue

  • Obesity is one of the most discussed public health issues, second only to tobacco use in economically advanced countries.
  • The rise in obesity rates globally correlates with increased health risks.
  • Obesity is linked to health problems such as cardiovascular disease, metabolic syndrome, and type 2 diabetes.

• Definitions of Overweight and Obesity

  • Overweight: Carrying more body fat than is deemed healthy (increased disease risk).
  • Obesity: Having an unhealthy body weight with potential health issues.
  • No perfect metric exists; however, Body Mass Index (BMI) is commonly used.

• BMI Calculations

  • BMI = \frac{weight\ (kg)}{height\ (m)^2}
  • Classifications based on BMI:
  • Underweight: BMI < 18.5 kg/m²
  • Normal weight: 18.5 ≤ BMI < 24.9 kg/m²
  • Overweight: 25 ≤ BMI < 29.9 kg/m²
  • Obese: BMI ≥ 30 kg/m² (Class I: 30-34.9 kg/m², Class II: 35-39.9 kg/m², Class III: ≥ 40 kg/m²)

• Limitations of BMI

  • Doesn't account for body composition (e.g., lean mass vs. fat mass).
  • Athletes may be misclassified as overweight or obese.

• Population Differences in BMI

  • Variations in health risks among different populations; different BMI cut-off values are suggested for certain ethnic groups (e.g., Asian populations).
  • Youth BMI definitions differ based on percentiles rather than fixed thresholds.

• Caloric Balance Equation

  • To maintain a healthy weight, energy intake must equal energy expenditure.
  • Energy Balance = Caloric Intake - Caloric Expenditure
  • Measures of energy expenditure include Basal Metabolic Energy Expenditure (BMEE), Physical Activity Energy Expenditure (PAEE), and Thermic Effect of Food (TEF).

• Weight Loss and Management

  • To lose 1 pound (0.45 kg) of fat, one must create a deficit of approximately 3,500 kcal.
  • Regular physical activity is essential for achieving and maintaining a healthy weight.
  • Minimum recommended activity: 150 minutes per week.

• Prevalence of Obesity

  • The CDC reported that over 70.7% of US adults over age 20 are overweight or obese.
  • Globally, over 1.9 billion adults are overweight, with 650 million considered obese.

• Health Risks Associated with Obesity

  • Health issues linked to obesity include:
  • Coronary heart disease (CHD), Type 2 diabetes, dyslipidemia, stroke, liver and gallbladder disease, certain cancers, hypertension, sleep apnea, osteoarthritis, and reproductive issues.

• Factors Influencing Overweight/Obesity

  • Modifiable Factors: Physical inactivity, excess caloric intake, low socioeconomic status.
  • Nonmodifiable Factors: Age, genetics, ethnicity, and metabolic rate.

• Physical Activity Guidelines for Adults and Youth

  • Adults: 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity activity weekly for health benefits.
  • Youth should engage in at least 60 minutes of daily moderate- or vigorous-intensity physical activity to maintain a healthy weight.

• Psychological and Behavioral Outcomes

  • Regular physical activity improves self-esteem, self-efficacy, reduces depression and anxiety, and aids in effective weight management.

• Assessment Techniques for Body Composition

  • Methods include visual inspection, BMI, waist circumference, skinfold measurements, dual-energy X-ray absorptiometry (DXA), hydrostatic weighing, and bioelectrical impedance analysis (BIA).
  • Waist circumference to categorize abdominal fat: < 40 inches for men and < 35 inches for women suggest lower health risks.

• Economic Impact of Obesity

  • Direct links between obesity and healthcare costs, projected to rise significantly by 2030, costing potentially billions annually due to associated chronic diseases and obesity treatment.