Energy balance and body weight

                                           Energy balance

n     People spend energy and eat periodically to refuel



n     Ideally – energy intakes cover energy exptenditure

  (a person is mainteining body weight)



                                      Positive energy balance

n      If more energy is taken in than is expended



                =>



                The person gains weight







n      Excess energy => fat

    n    3500 kcal eaten in excess = 1 pound of body fat (454 g)

    n    1 pound of body fat – a mixture of fat, protein and water

        n    87 % body fat is fat (395 g x 9 kcal = 3500 kcal)



                                      Negative energy balance

n     If more energy is spent than is taken in



               =>



            The person loses     weight

                                             Energy in

n      The kcalories foods and beverages provide

  n     Kcalorie – a unit of heat energy

n      Food energy value can be determined by:

  n     Direct calorimetrie

      n    measure the amount of heat released

  n     Indirect calorimetrie

      n    measure the amount of oxygen cosumed

      

n      The energy value of food

  n     1 g Carbohydrates      4 kcal

  n     1 g Fat                  9 kcal

  n     1 g Proteins             4 kcal

  n     1 g Alcohol             7 kcal

                                             Energy out

n    The kcalories the body spends





                                  Components of energy expenditure

n     1. Basal metabolism  (BM)



    n   2/3 of energy

    n   Energy neded to maintain life when a body is at complete digestive, physical, and emotional
    rest

    n   Basal metabolic rate (BMR)

        n    the rate of energy used for metabolism under specific conditions (after 12 hour fast
        and restful sleep, without any PA)

    n   Resting metabolic rate  (RMR)

        n    Similar to BMR, but slightly higher

        n    A measure of a person at rest in a comfortable setting, but with less stringent
        criteria for the number of hours  fasting

                        Factors that affect the BMR (Whitney, Rolfes, 2002)

                                  Components of energy expenditure

n    2. Physical activity  (PA)



  n    Voluntary movement of the sceletal muscle and support systém

  n    The most variable component of EE

  n    The amount of energy needed for PA depends on three factors:

    n   Muscle mass

    n   Body weight

    n   Activity  (duration, frequency, intensity)



                                  Components of energy expenditure

n    3. Thermic effect of food (TEF)



    n   An estimation of energy required to process food (digest, absorb, transport, metabolize, and
    store ingested nutrients)

    n   Also called specific dynamic effect (SDE) or specific dynamic activity (SDA)

    n   10 % of EE

    n   TEF is greater for high carbohydrate meal than for high fat meal



                                   Estimating energy requirements



n    In calculation are considered following componends



    n   Energy spent on basal metabolism

    n   Energy spent on physical activity

    n   Energy spent on digesting and metabolizing food



                                  Energy spent on basal metabolism

n      1. The Harris-Benedict Equation



 Males:  66 + (13.7 x W) + (5 x H) - (6.8 x A)                

 Females:  655 + (9.6 x W) + (1.7 x H) - (4.7 x A)



where W = actual weight in kg (weight in lb/2.2 lb/ kg)

           H = height in cm (height in inches x 2.54 cm/in)

           A = age in years



n      2. quick and easy estimate



       Males:  kg x 24 = kcal/day

       Females: kg x 23 = kcal/day

                                 Energy spent on physical activity

                                     Energy spent on digesting
                                       and metabolizing food



                        10 % of  BMR





  A person who ingests 2000 kcalories in a day probably spends about 200 kcalories the TEF



                                  Body weight and body composition

n    Body composition

  n    The proportions of muscle, bone, fat, and other tissue that make up a person´stotal body
  weight



                                  Body weight = fat + lean tissue

                                         (including water)



                                        Healthy body weight

n    Is defined by the three criteria



    n   A weight within the suggested range for height

    n   A fat distribution pattern that is associated with a low risk of illness and premature death

    n   A medical history that reflects an absence of risk factors asociated with obesity (elevated
    blood cholesterol, blood glucose, blood pressure)

                                      Weight-for-Height Chart





                                          Body mass index



                                   Body fat and its distribution

                                       Body Fat Guide - WOMEN

                                   Body fat and its distribution

                                        Body Fat Guide - MEN

                                   Body fat and its distribution

n     Athletes - lower percentage

  n    5 – 10 % for men

  n    15 – 20 % for women

  

n     Distribution

  n    Intra-abdominal fat – around the organs of the abdomen

      n    Referred to  as central obesity

      n    Is associated with increase risk of heart disease, stroke, hypertension, diabetes, some
      types of cancer

      n    More common in men

      n    In women past menopause

                              Upper-body fat – apples (android obese)
                               Lower-body fat – pears (gynoid obese)

                              Theoretical contributors to body weight

                                   Body composition compartments