energy balance and healthy weight

• Health risks from


  • Overweight
  • Underweight

  
• Weight "control" MISCONCEPTIONS


  • Focus on weight
  • Focus on controlling weight
  • Focus on short-term endeavors

  
• BODY COMPOSITION IS WHAT NEEDS TO BE CONTROLLED
• Healthy Weight


  Weight at which individual: Eats nutritiously, Exercises, Is free of health problems and disease
• BMI


  • For adults (≥ 20 years old)
  • For children and adolescents: BMI-for age and gender, Weight – height, weight-for-age and height-for-age measurements
  • Waist circumference and Waist/hip ratio: Waist/Hip ratio is calculated to measure the degree of visceral adiposity, Good marker for increased risk of chronic diseases
  • Used to evaluate health risks of obesity: Body mass index (BMI), Waist circumference, Disease risk profile

  
• Body Mass Index (BMI)


  • BMI = Weight (kg) / height2 (m)
  • Underweight <18.5
  • Overweight >25.0 through 29.9
  • Obesity ≥30
  • Risks at same BMI follow racial lines: White > Black (more LBM)

  
• Not everyone can match healthy weight target of BMI of 19 to 25

  
• BMI Drawbacks


  • Amount or location of fat
  • Limited BMI use with: Athletes, Pregnant and lactating Women, Adults over age 65
  • Diagnosis requirements: BMI + body composition and fat distribution, Waist circumference

  
• Underweight, Overweight, and Mortality

  
• Causes of overweight


  • Poor diet and inactivity
  • Genetics
  • Physiological, metabolic, biochemical, and psychological factors
  • Hypothyroidism: BMR reduces, should be corrected with medication

  
• Obesity itself classified as CHRONIC DISEASE
• Obesity-related illnesses


  • Heart disease, diabetes, arthritis, cancer
  • Dying young: With extreme obesity, Obesity = smoking in risk
  • Diabetes, Central obesity, Abdominal hernias, complications in pregnancy and surgery, flat feet, gallbladder disease, gout, high blood lipids

  
• Fat Distribution


  • Fat in abdominal cavity associated with greater health risks than fat in thigh, buttocks, and hip area
  • Person with pear-shaped body has lower risk for disease than someone with apple-shaped body
  • Waist-to-hip ratio is a health indicator

  
• Risks from Central Obesity


  • Diabetes, Heart disease, Hypertension, Gallbladder stones, Stroke, Some types of cancer
  • Risk of ALL cause mortality is higher for visceral fat VS subcutaneous fat (abdomen, thighs, hips and legs)

  
• Adipokines


  Regulate inflammatory processes, Central obesity causes a shift favoring increase in inflammation and insulin resistance of tissues
• More Free fatty acids, Fat collects in the liver and around the heart
• Factors affecting fat distribution - more central obesity


  • Gender: men and women after menopause
  • Moderate to High intakes of Alcohol
• Energy budget


  Change in energy stores = energy in - energy out
• Energy in


  Foods and beverages, For each 3500 calories you eat in excess of expenditures, you store approximately 1 pound (1lb = 450g) body fat

  
• Energy out


  Varies widely, Lifestyle and metabolism
• In some situations, positive energy balance is normal and healthy: Pregnancy, Infants and Children, Underweight Individuals

  
• Past years: Availability of food (high-fat, high-sugar), Vending machines, fast-food restaurants, Super-sized portions

  
• Bomb calorimeter


  Closed container surrounded by a known volume of water, Explode food pieces in a special water lined chamber and measure the heat given off from the explosion
• Direct Calorimetry


  Measuring heat production by the body, Individual inside an insulated chamber with water pipes measuring the rise of water temperature in degrees Celsius
• Indirect Calorimetry


  Measures the amount of expended energy based on oxygen consumption: 1 liter of O2 consumed = 5 Cal expended
• Components of Energy Expenditure

  • Basal metabolism (BMR): Involuntary activities that are necessary to sustain life, Voluntary activities: Intentional activities done by voluntary muscles (sports/ physical activity), Thermic effect of food: About 10% of a meal's energy value
• Thermogenesis


  Non-voluntary activity triggered by cold conditions or overeating (e.g. Shivering when cold, or fidgeting), Smallest contribution to TEE
• Non-exercise Activity Thermogenesis (NEAT)


  Energy expended for everything we do that is not sleeping, eating or sports-like exercise, Small contribution but accumulates over time, Important for individuals with a sedentary lifestyle, NEAT increases with overfeeding and decreases with underfeeding
• Harris Benedict Equation


  Based on sex, height, weight, and age, For males: =66.5 + 13.8 x weight (kg) + 5.0 x height (cm) - 6.8 x age (years), For females: =655 + 9.6 x weight (kg) + 1.8 x height (cm) - 4.8 x age (years)

  
• TEE = BMR * PA Factor
• Upper body fat distribution

  Increased cardiovascular, hypertension, diabetes risk, More common in men (encouraged by testosterone), Assessed by measuring Waist Circumference: >94 cm in men, >80 cm in women → Upper body obesity

  
• Lower body fat distribution


  More difficult to lose than abdominal fat, More common in women (encouraged by estrogen-stores of extra energy for pregnancy/lactation)

  
• Waist-to-hip ratio


  Health indicator
• Measuring Waist Circumference


  Measurement around the point near the belly button, Healthy WC for men: < 102 cm, Healthy WC for women: < 88 cm

  
• Average Body Composition of Men and Women
• Healthy range of body fat

  Man: 18 to 21 percent, Woman: 23 to 26 percent

  
• Desirable % body fat


  Men: 8-24%, Women: 21-35%

  
• Percent Body Fat: American Council on Exercise Classification


  • Essential Fat: Women 10-13%, Men 2-5%
  • Athletes: Women 14-20%, Men 6-13%
  • Fitness: Women 21-24%, Men 14-17%
  • Acceptable: Women 25-31%, Men 18-24%
  • Obesity: Women ≥ 32%, Men ≥ 25%

  
• Measures of Body Composition and Fat Distribution


  • Body composition, Skin fold test, Underwater weighing, Bioelectrical impedance, Dual-energy X-ray absorptiometry (DEXA)
• Three Methods of Assessing Body Fatness

  • Skinfold measures: use of caliper to gauge thickness of a fold of skin
  • Bioelectrical impedance: method determines body fatness by measuring conductivity. Lean tissue conducts painless electric current, fat tissue does not.
  • DEXA: two low-dose x-rays that differentiate among fat-free soft tissue, fat tissue, and bone tissue with accurate measurement of total fat and distribution of fat in all but extremely obese subjects