-
BMI
- Being both overweight and underweight present risks to health
- –Overweight: over
- fatness of moderate degree
- BMI 25.0 - 29.9
- –Underweight: too little body fat
- BMI<18.5
-
How to Calculate BMI
- Measurement of weight (in
- lbs.) divided by height (in inches) squared, then multiplied by 703
- -For Example:
Your instructor’s pre-pregnancy weight = 161 lbs, and height 5’9”
163/ (69)2 x 703 = 24.07 (healthy – whew!!)
-
BMI (Body Mass Index)
- 18.5-24.9 heathly
- 25-29.9 overweight
- 30-39.9 obese
- <40 morbidly obese
-
Pitfalls
of BMI
Doesn’t measure fat %
- Doesn’t work for athletes,
- elderly (shrinking), or pregnant/lactating women
- Can’t measure fat location,
- also a factor
- –Visceral fat – found around the stomach
- (central obesity), more health risk with this
- –Subcutaneous fat – found below the skin, less
- attractive but less health risks
-
The Price
of Obesity
Health costs
- Increase risk of
- stroke, diabetes, some cancers, high blood pressure, heart attack
- Second only to
- tobacco use in causes of preventable death
Social costs
- Ridicule, loss
- of social acceptance
- Inability to
- participate in activities
Financial costs
- Billions spend
- each year treating effects of obesity
-
What causes weight gain?
- More energy input than
- energy output
Extra calories stored as FAT
- 1 lb of fat =
- about 3,500 calories
- Need to know your Estimated
- Energy Requirements
- Accounts for
- age, height, weight, gender, and physical activity
- Affected by your
- BMR and voluntary activities
-
BMR vs.
Voluntary Activities
Voluntary activities
- Sports, working
- out, things we do extra that require energy
- Over time, these
- things increase our BMR
- Basal Metabolic Rate (BMR) –
- the energy required to sustain life
- Maintaining body
- temperature, functioning systems, etc..
- Affected by
- thyroid, pregnancy, height, gender, etc.
- The more lean muscle, the
- higher your BMR
- Estimated men –
- (lbs) x 2.2 kg x 24 = calories needed/day
- Extimated women – (lbs) x
- 2.2 kg x 22 = calories needed/day
-
How do I measure Fat?
How much is ideal?
Measure Body Composition by:
- Fat fold test –
- pinches skin under arm /on back
- X-ray absorption
- – measures density
- Underwater test
- – fat less dense than water
- Electrical
- impedance – fat doesn’t conduct electricity well
- Ideal fat %
- Women – 20-30%
- of body mass
- Men – 12-20% of
- body mass
-
What causes Obesity?
- Stress
- Birth order, genetics
- Increased wealth
- Lower education
- Sedentary lifestyle
- Meal skipping
- Maternal obesity/famine during gestation
- Many, many more – What do
- you think is the biggest factor?
-
Hunger, Appetite and Hormones
- Ghrelin – released in stomach,
- triggers brain to feel “hunger”
- Endorphins – associated with
- “feeling good” after exercise, can by released in response to other stimuli
- (i.e. smell of apple pie), stimulate “appetite”
- Leptin – triggers that “full”
- feeling, studies show low levels of leptin
- associated with obesity
Satiety- sense of fullness, the state of being satiated
Appetite- the psychological need for food
Hunger- the physiological need for food
-
Why “diets” don’t work
- “Diets” don’t work, they are
- short term
- Only life-changing habits
- work
- What happens on a strict
- ”diet”
- Initial rapid
- weight loss due to using glycogen stores and water loss
- Brain start
- using fats for energy, leads to fatigue, headaches, weakness
- Lean muscle can
- be converted into energy, body starts “wasting”, use of proteins increases
- nitrogen waste, hard on kidneys
- Body “thinks”
- it’s a famine, slows down BMR, hold onto foods better, leads to constipation,
- and when you “cheat” the lower BMR causes the yo-yo effect
-
The Best Approach
- Eat small, frequent meals –
- body never goes into “starvation” mode
Balance between carbs, fats, and protein
- Fiber for a
- health GI tract
- Fats for
- hormones, padding, etc..
- Proteins for
- enzymes, muscles, etc..
- Exercise, Exercise, Exercise
- – it keeps your BMR up and your heart rate down
-
Disorders of Eating Habits
- Bulimia nervosa - purge, binge
- Anorexia nervosa - self starvation
-
Carb Loading
eat carb rich meals before big event, max out glycogen stores
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