Weight loss and exercise

ObesityOverweight: BMI = 25.0 - 29.99

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 LossCaloric 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 OutCaloric 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 = 1,800-2250 kcal

TEF = 300 kcal

PA = 450-900 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’...

…500-1000 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.

60-75% of daily caloric expenditure

Metabolic RateGenetics

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] 4

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60%

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30

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600

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900

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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.

25-30 calories per pound of body weight to gain weight (20 calories per pound to maintain weight)

...or...

500-1000 extra calories per day.

Weight Gain

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: can’t 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