NSC 170C1 1st Edition Lecture 20 Outline of Last Lecture I Alcohol Outline of Current Lecture II Healthy Body Weight A Body mass index B Energy balance Current Lecture I Healthy Body Weight A Healthy Body Weight a body weight that doesn t increase the risk of developing weight related health problems or disease i A range appropriate for younger gender height and muscle mass ii A realistic weight you can maintain naturally by regular exercise and consuming a nourishing diet iii Weight management maintaining your weight within a healthy range II Body mass index BMI a calculation of your weight in relation to your weight A Under weight is associated with increased risk of infection and higher overall risk of mortality B Obesity is associated with 50 to 100 percent higher risk of premature death i Not a direct measurement of percent body fat and doesn t asses if weight is predominantly muscle of fat ii Athletes and individuals with high muscle mass may have a low percentage of body fat iii Chronic weight loss in older adults may cause low BMI and in individuals less than 5 ft will have a high BMI but doesn t necessarily mean unhealthy Your body fat location A Storing excess fat around the waist versus the hips and thighs is shown to increase risk of heart disease diabetes and hypertension B Central diabetes is due to storing too much visceral fat in the abdomen i Subcutaneous fat is the fat sandwiched between your skin and muscles ii Waist is a quick indicator of unhealthy fat C Waist to hip ratio III D E F G Health risk visceral fat releases fatty acids which travel to the liver and are thought to cause insulin resistance and increases LDL and decreased HDL cholesterol Healthy males average 16 to 21 percent of weight as body fat Healthy females average 22 to 26 percent weight as body fat Techniques to measure percentage of body fat include Skinfold thickness measurements Bioelectrical impedance Dual energy X ray absorptiometry DNA Underwater weighing Air displacement Energy Balance A Energy balance the state when energy intake and energy expenditure are equal i Positive energy balance when you consume more calories than you expend causes storage of body fat ii Negative energy balance when calories intake falls short of needs body breaks down stored fat for fuel B You determine if you are in positive or negative energy balance by comparing your caloric intake with your energy expenditure BMR 50 70 Physical activity 20 35 TEF 10 C Your BMR will increase your energy needs i Basal metabolism is the amount of energy expended to meet the basic physiological needs that enable organs and cells to function also referred to as basal metabolic rate BMR ii Lean body mass is the factor that most affects BMR iii BMR is also affected by age gender body size genes ethnicity emotional and physical stress thyroid hormones nutritional state environmental temperature and caffeine and nicotine intake D BMR contribution Liver 29 Brain 19 Heart 19 Kidney 7 Skeletal muscle 18 The rest 17 Total 100 Physical activity will increase your energy needs i Physical activity will increase your energy needs ii For very physically active individuals the amount of energy expended in physical activity can double their BMR iii The more physical activity you routinely incorporate the more calories you will need to meet your energy needs IV Calculating your energy out EEE A BMR formula wt in kg Males 10 18 17 5 x wt 651 18 30 15 3 x wt 679 30 60 11 6 x wt 879 60 13 5 x wt 487 Women 10 18 12 2 x wt 746 18 30 14 7 x wt 496 30 60 8 7 x wt 829 60 10 5 x wt 596 Lbs 2 2 wt in kg Physical Activity Level Range Men Women Light 0 1 0 3 0 1 0 25 walking to class rec center 1 2x week 1 hr each visit Moderate 0 3 0 50 0 25 0 40 rec center 3 5x week 1 5 hr each visit Medium Heavy 0 5 0 7 0 4 0 6 rec center 5 7x week 2 hrs each visit Heavy 0 7 0 90 0 6 0 80 athlete who works out 3 hours per day BMR X Activity kcals burned by Physical Activity B What s Your Estimated Energy Expenditure i Mike 18 years old 160 lbs Works out 4 days per week on average at Rec Center Range 0 3 0 5 for Males ii He eats on average 3 300 kcals iii 160 2 2 72 7 kg iv Estimated Energy expenditure BMR PA TEF v BMR 15 3 x 72 7 679 1112 3 679 1791 3 kcals vi Physical Activity BMR x 0 4 1791 3 X 0 4 716 5 kcals vii Thermic Effect of Food 10 kcal intake viii 10 x 3 300 330 kcals ix Estimated Energy Expenditure 1791 3 716 5 330 2837 8 x Round to whole numbers EEE 2838 V What are the Effects of an Energy Imbalance A Mike consumes on average 3 300 kcals B Mikes estimated energy expenditure is 2838 C In 300 out 2838 D Too Few Calories Can Cause Underweight i If you consume fewer calories than you need on a daily basis your body will draw on energy stores to make up the deficit ii Glycogen and fat will be used as fuel to meet energy needs until the next time you eat iii Amino acids from the breakdown of body protein particularly muscle can be used to make glucose E If you continue in negative energy balance over time you will lose weight F Too Many Calories Can Cause Overweight G Eating more calories than you need regardless of the food source will result in the body storing the excess as fat H Your body has an unlimited capacity to store fat