Weight loss and exercise

Obesity Overweight: BMI = Obesity BMI 30 Body fat > 25% for men Body fat > 30% for women Americans: Overweight: 32% Obese: 34%

Obesity Genetic factors 25% of the transmissible variance for fat mass and percent body fat Cultural factors (30%) Individual choices (45%)

Calorie A measure of HEAT (1 calorie = heat required to raise 1 gram of water by 1 degree Celcius in temperature) Heat, or Calorie, represents Energy

Weight Loss Caloric balance or imbalance Energy In > Energy Out = Weight Gain Energy In < Energy Out = Weight Loss Examples Energy In: Big Mac 540 kcal Energy Out: Run 40 minutes

Energy Out Caloric expenditure 1. Resting Metabolic Rate = 60-75% 2. Thermic effect of food = 10% 3. Physical activity = 15-30% of daily caloric expenditure Example 3000 calories in one day RMR = 1, kcal TEF = 300 kcal PA = kcal

Energy In Fat = 9 calories per gram Alcohol = 7 calories per gram Carbohydrate = 4 calories per gram Protein = 4 calories per gram

Weight Loss Reduce Energy In and/or Increase Energy Out... … fewer calories per day (3,500-7,000 fewer calories per week) Recommendations: 1-2 lbs of weight loss per week

Reducing Caloric Intake

Reducing Calorie Intake

Rapid Weight Loss / Low Calorie Diets = weight loss greater than 1-2 pounds per week. Where does the weight loss come from? Water loss, Muscle loss, etc. Metabolic rate?

Caloric Intake and Resting Metabolic Rate

Metabolic Rate Resting Metabolic Rate is VO2 measured at rest ave. resting VO2 = 3.5 ml/kg/min Estimated RMR = 1 kcal/kg/hour For a 183 pound person, RMR = 2000 kcals % of daily caloric expenditure

Metabolic Rate Genetics Gender Fat-free mass Dieting Hormones (e.g. Thyroid hormones, etc) Over eating (thermogenesis) Medications/Drugs

Increasing Caloric Expenditure

Physical Activity and Body Fat

Exercise and Weight Loss Exercise alone less effective than diet alone Duration: > 2000 calories/wk EXAMPLES OF KCAL expenditure 0.77 kcal / kg / mile for walking 1.53 kcal / kg/ mile for running

Exercise and Weight Loss Exercise may be most critical to help maintain weight loss Exercise helps to maintain muscle mass and metabolic rate

Exercise and Weight Loss Aerobic exercise v Resistance exercise WORKOUT CALORIES resting metabolic rate Aerobic Exercise: Duration versus Intensity

Fat Burning Zone?

Exercise and Fat Metabolism Is low-intensity exercise best for burning fat? [A Closer Look 4.3] 40% fat 60% fat ~20% fat 300 total kcals 600 total kcals 900 total kcals

Successful Weight Loss diet and exercise Diet: limited caloric intake (source of calories is unimportant) Exercise: increase physical activity

Genetics Body Type / Somatotype Weight Gain

Caloric intake greater than caloric expenditure calories per pound of body weight to gain weight (20 calories per pound to maintain weight)...or extra calories per day. Weight Gain

Caloric distribution Carbohydrates - 60 to 70% of total calories Protein - 10 to 15% of total calories Fat - remainder of total calories.

Weight Gain Example for 200 pounds. Carbohydrates: energy for anabolism (~3000 kcals) Protein: amino acids for anabolism (~1200 kcals) Fat: cant avoid it (~800 kcals) PSM

Recovery/Rest Eccentric muscle contractions damage muscle proteins. Proteins are replaced for the next 48 hours or more. Adequate rest and recovery period are critical for complete muscle repair and growth Weight Gain