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  • Energy Intake and Expenditure Outcome 3
  • Kcals of energy for macronutrients
    • 1g Carbohydrates = 4kcals of energy
    • 1g Protein = 4Kcals of energy
    • 1g Fat = 9kcals of energy
  • Estimating Energy Requirements
    • BMR (Basal Metabolic Rate) – this is the minimal calorie requirement needed to sustain life in a resting individual
    • You would burn this amount of energy if you slept all day or rested in bed for 24 hours
    • A number of factors can affect BMR
    • Some factors speed your BMR up so you are burning more calories per day to stay alive
    • Others slow your metabolism down so you need to eat fewer calories to stay alive
    • Make a list of what you think the different factors are, giving reasons.
  • Factors affecting BMR
    • Age
    • Body size
    • Growth
    • Body Composition
    • Fever
    • Stress
    • Environmental temperature
    • Fasting
    • Thyroxin
  • Estimating energy and macronutrient requirements
    • To estimate energy requirements you need to calculate your Basal Metabolic Requirements (BMR)
    • This is measured in kilocalories per day
    • for a 10-17yr old male BMR = 17.7W(weight in Kg’s) + 657
  • BMR
    • Males 10-17yrs BMR=17.7W+657
            • 18-29yrs BMR=15.1W=692
            • 30-59yrs BMR=11.5W+873
    • Females
            • 10-17yrs BMR=13.4W+692
            • 18-29yrs BMR=14.8W+487
            • 30-59yrs BMR= 8.3W+846
  • Estimating energy and macronutrient requirements
    • You also need to consider your level of physical activity and training
    • Simplest method of estimating your total energy requirements:
    • Multiplying BMR by PAL (physical activity level)
  • PAL
    • To calculate PAL you have to make assumptions about the energy demands of your occupational and non-occupational activity levels
  • Pal for three levels each of occupational and non-occupational activity 1.7 1.9 1.7 1.8 1.6 1.6 Very active 1.6 1.8 1.6 1.7 1.5 1.5 Moderately active 1.5 1.7 1.5 1.6 1.4 1.4 Non-active F M F M F M Heavy Moderate Light Non-occupational activity Occupational Activity
  • Alcohol
    • Concentrated source of energy
    • Produces 7kilocalories per gram
    • This energy is not available to the working muscles
    • Excess energy from alcohol is stored as fat
    • Current safe limits recommended by Health Education Authority – 3-4 units/day for men, up to 2-3 units /day for women
  • Energy needs and energy balance
    • Energy balance is when the amount of energy taken in = the amount of energy used (output)
    • 4 major components to energy output
        • Resting metabolic rate
        • Dietary thermogenesis
        • Physical activity
        • Adaptive thermogenesis
  • Energy needs and energy balance
    • Basal Metabolic Rate (BMR) account for 60-75% of total energy output
    • BMR will depend on body composition e.g. gains in muscle mass will increase BMR
    • Sex, age and genetic background also have a bearing
    • Dieting (low energy intake) can lead to a reduced BMR
  • Energy needs and energy balance
    • Dietary Thermogenesis (DT) – energy expended above BMR – digestion, absorption, transportation and storage of food
    • Influenced by calorie content and composition of meals eaten
    • High energy intake and regular eating pattern help maintain higher rates of DT
  • Energy needs and energy balance
    • Physical Activity (PA) – most variable component of energy expenditure
    • This is additional expenditure above BMR and DT
    • How much will depend on level of activity, lifestyle, how often and how energetically and for how long we participate in sport and exercise
  • Energy needs and energy balance
    • Adaptive Thermogenesis (AT) is energy expenditure due to environmental or physiological stresses placed on the body
    • Changes in temperature - shivering
    • Stress that causes anxiety or fidgeting
  • Energy needs and energy balance
    • When energy intake is greater than output
    • this is known as
    • Positive Energy Balance –
          • Weight is gained
    • When energy intake is less than output, we
    • use up fat stores, this is known as
    • Negative Energy Balance
          • Weight is lost
  • Energy needs and energy balance
    • Sportspeople are concerned about maintaining or attaining an optimal body weight
    • Some sports set weight restrictions e.g.
      • Body building
      • Boxing
      • Horse racing
      • Martial arts
      • Rowing
  • Energy needs and energy balance
    • Some sports benefit from increased body size e.g. rugby or American football
    • Other sports need a low body weight which may be below natural weight – weight-controlled sports e.g.
        • Distance running
        • Gymnastics
        • Diving
  • Energy needs and energy balance
    • To maintain a low body weight or reduce weight whilst also maintaining a nutritionally suitable diet inappropriate weight loss practices can be found e.g.
      • Fasting
      • Skipping meals
      • Laxative abuse
      • Binging
      • Purging
      • Intentional dehydration – use of sweat-suits or saunas