Energy Balance Notes

Chapter 5: Energy Balance

Overview of Energy Balance

  • Energy Balance Definition:
    • Regulates the relationship between energy intake and expenditure.
    • The balance occurs under varying conditions; for instance, when the energy required changes or when food intake is inconsistent.

Homeostasis and Survival

  • Concept of Homeostasis:
    • Describes the equilibrium where the number of kilocalories consumed equals the energy used.
  • Survival Mechanism:
    • Energy balance is critical for survival, particularly during periods characterized by feast or famine.

Energy Intake

  • Eating Behavior:
    • Influenced by environmental factors and regulated through internal mechanisms.

Energy Expenditure Factors

  • Adaptive Thermogenesis:
    • An evolutionary response that helps the body manage conditions of feast and famine.

Measuring Energy

  • Calorie Definition:
    • The amount of energy necessary to raise or lower 1 kilogram of water by 1° Celsius.
  • Kilocalorie (k calorie or k cal):
    • Equals 1,000 calories.
  • Joule:
    • A unit of energy measurement.

Energy Nutrient Values

  • Kilocalorie Values by Nutrient Types:
    • 1 gram of carbohydrate or protein = 4 k calories.
    • 1 gram of fat = 9 k calories.
    • 1 gram of alcohol = 7 k calories.

Determining Energy Values in Foods

  • Methods for Measuring Energy Content:
    • Bomb Calorimeter:
    • Measures energy content by burning food, determining the generated heat energy through temperature changes in surrounding water. The equation used is:
      extProtein+extOxygen=extHeatEnergy+extWater+extCarbonDioxideext{Protein} + ext{Oxygen} = ext{Heat Energy} + ext{Water} + ext{Carbon Dioxide}
    • Carbohydrate or fat can replace protein in the equation.
    • Human Body Measurement Approaches:
    • Direct measurement of caloric burn during metabolism.
    • Indirect measurement through calorimetry.

Harris-Benedict Equation for Resting Energy Expenditure (REE)

  • Weight Conversion:
    • To convert pounds to kilograms:
      1extkilogram=2.2extpounds1 ext{ kilogram} = 2.2 ext{ pounds}
    • Body weight in pounds is divided by 2.2.
  • Height Conversion:
    • To convert inches to centimeters:
      1extinch=2.54extcentimeters1 ext{ inch} = 2.54 ext{ centimeters}
    • Height in inches multiplied by 2.54.
  • REE Calculation for Men:
    • extREE=66.5+(13.8imesextweightinkg)+(5imesextheightincm)−(6.8imesextageinyears)ext{REE} = 66.5 + (13.8 imes ext{weight in kg}) + (5 imes ext{height in cm}) - (6.8 imes ext{age in years})
  • REE Calculation for Women:
    • extREE=65.5+(9.6imesextweightinkg)+(1.8imesextheightincm)−(4.7imesextageinyears)ext{REE} = 65.5 + (9.6 imes ext{weight in kg}) + (1.8 imes ext{height in cm}) - (4.7 imes ext{age in years})

Quiz Question

  • Question: The energy content of individual foods is measured by a device called a:
    • Option A: K calorie
    • Option B: Joule
    • Option C: Adaptive thermogenesis
    • Option D: Bomb calorimeter
  • Correct Answer: D - A bomb calorimeter.
    • Definition: An insulated container where food is burned to measure the heat produced.

Components of Energy Expenditure: Resting Energy Expenditure

  • Factors influencing REE:
    • Age
    • Sex
    • Growth
    • Body Size
    • Climate
    • Genetics

Components of Energy Expenditure: Thermic Effect of Food (TEF)

  • Definition of TEF:
    • Heat produced by the body post-meal.
  • Nutrient Impact:
    • Protein and carbohydrates yield a larger TEF compared to fat.
  • Kilocalories:
    • Counted based on the source of food.

Components of Energy Expenditure: Physical Activity

  • Daily Activity:
    • Nonexercise activity thermogenesis (NEAT): daily activities that burn calories.
  • Types of Exercise:
    • Thermic effect of exercise and adaptive response to exercise increase efficiency.
  • Exercise Impact on Appetite:
    • Influences through neurotransmitters dopamine and serotonin.

Components of Energy Expenditure: Physical Activity (Continued)

  • Aerobic Exercise:
    • Supported by increased oxygen intake, notable for health benefits.
  • Anaerobic Exercise:
    • Does not require oxygen and enhances strength and toughness.

Components of Energy Expenditure: Additional Activities

  • Involves balance and stretching, bone strengthening exercises, and interaction with diet.

Energy Intake

  • Energy Intake Considerations:
    • The mean reported energy intake approximates energy requirements.
    • Assessments should consider:
    • Kilocaloric density of foods.
    • Nutrient density of foods; for example, identifying 'empty' k calories.
    • Portion sizes.

Portion Sizes and Distortion

  • Portion Distortion Examples Over 20 Years:
    • Bagel: 3 inches (previous) → 6 inches (current)
    • Cheeseburger: 4.5 ounces → 8 ounces
    • Popcorn (medium bag): 5 cups → 11 cups
    • Soda: 6.5 ounces → 20 ounces
    • Source: National Heart, Lung, and Blood Institute.

Dietary Recommendations

  • Guidelines from Major Health Organizations:
    • Best practices for maintaining a healthy body weight.
  • Current nutrient guidelines for adults:
    • Carbohydrates: 45% to 65% of total energy.
    • Protein: 10% to 35% of total energy.
    • Fats: 20% to 35% of total energy.

Quiz Question on Nutrient Density

  • Question: Which of the following foods are considered to have empty k calories?
    • Option A: Table sugar
    • Option B: Cantaloupe
    • Option C: Skim milk
    • Option D: Whole milk
  • Correct Answer: A - Table sugar.
    • Definition of Empty k Calories: Foods that provide k calories with little to no nutrients.
    • Comparison of Nutrient Density:
    • Cantaloupe: High nutrient density.
    • Skim Milk: Approximately 90 k calories in 8 ounces.
    • Whole Milk: Approximately 150 k calories in 8 ounces. Skim milk is higher in nutrient density than whole milk.