The Highs and Lows of Body Weight

1
Unit 9

• The Highs and Lows of Body Weight

2
Variations in Body Weight

• Wouldnt it be terrific if your body adjusted
  your food intake based on a healthy level of body
  fat stores? Then you wouldnt have to worry about
  being too thin or getting too fat. Why doesnt
  that happen?

3
How is weight status defined?

• 1500s- moon-faced and pear-shaped was in
• 1930s- Jean Harlow
• 1950s- Marilyn Monroe
• 1960s- Twiggy
• 2000- Calista Flockhart

4
Assessing appropriate weights

• Weight-for-Height
• Body Mass Index (BMI)
• Percent body fat
• Assessing children and adolescents

5
Weight for Height

• Women 5 feet tall 100 lbs
• 5 lbs for each additional inch
• Example 55 100 25 125 lbs 10
• Men 5 feet tall 106 lbs
• 6 lbs for each additional inch
• Example 510 106 60 166 lbs 10
• Does not correspond to percent body fat

6
Body Mass Index

• Divide body weight (kg) by height (m) squared
• See nomogram on page 9-4
• Underweight under 18.5 kg/m2
• Normal weight 18.5 25 kg/m2
• Overweight 25-30 kg/m2
• Obese 30 kg/m2 or higher

7
Assessing Children and Adolescents

• Growth Charts for Boys and Girls, ages
  2-20 years old
• Assess weight for height- not useful in measuring
  obesity

8
Percent Body Fat

• Skinfold Measurement
• Bioelectrical Impedance Analysis (BIA)
• Underwater weighing
• Magnetic Resonance Imaging (MRI)
• Dual-energy X-ray Absorpiotmetry (DEXA)

9
Influence of Obesity on Health

• Diabetes
• Hypertension
• Stroke
• Heart disease
• Certain types of cancer
• Gallbladder disease
• Shortened life Expectancy

• Discrimination
• Depression
• Infertility
• Accidents
• Skin disorders
• High cholesterol
• Low HDL-cholesterol

10
Everybody Needs Some Body Fat

• Hormones
• Cell walls
• Cushions internal organs
• Low body fat levels
• Delayed maturation in adolescence
• Infertility
• Accelerated bone loss

11
Body Fat Location is Important

• Pear shaped- fat stores around hips
• Not as many health risks
• Apple shaped- fat stores around waist
• Increased insulin resistance gt diabetes
• Increased triglycerides gt heart disease
• Increased blood pressure gt hypertension
• Men more likely to be apples women apples and
  pears

12
Assessing Body Fat Distribution

• Waist-to Hip ratio- apples
• Greater than .80 in women
• Greater than .95 in men
• Predicts risk of several chronic diseases

13
What causes Obesity?

• Three major factors contribute to the development
  of obesity
• Genetic background
• Dietary intake (too many calories)
• Physical activity (inactivity)

14
Are some people born to be obese?

• Heredity may account for 25-40 of the incidence
  of obesity
• Born with errors in metabolism that cause
• Or
• Born with genetic traits that predispose them to
  gain weight when the right environmental trigger
  exists

15
Twin studies

• Overfed identical twins gained weight similarly
  to each other but unlike others in the study
• Identical twins raised apart are less likely to
  have similar weights than twins raised together

16
Set-point theory

• Individuals programmed to weigh a certain amount
• Body weight will return to that level after
  weight is lost or gained
• Or
• Number and size of fat cells predisposes some
  people to obesity
• neither theory found to be true

17
Do obese children become obese adults?

• Obese children under age three with no obese
  parents- 8 are obese adults
• Obese children ages 10-14 with at least one obese
  parent- 80 are obese as adults

18
Role of Diet in Development of Obesity

• Everyone who is obese consumes more calories than
  the body needs
• This does NOT mean they overeat- some eat less
  than people who are not obese
• High-fat diets may promote obesity
• May be higher in calories than low-fat diets
• Body may be more efficient at converting fat to
  fat stores than carbs or protein to fat stores

19
Inactivity promotes obesity

• Decrease in activity may be partly responsible
  for increased in obesity
• Drive 2.5 miles burns 17 calories
• Bike 2.5 miles burns 122 calories
• Walk 2.5 miles burns 210 calories
• Convenience and time vs physical activity
• Too much TV?

20
Preventing Obesity in Children

• Early development of good food and activity
  habits
• Positive interactions around eating and body
  weight
• Do not focus on body weight and restrict food
• Family activities that encourage healthy
  lifestyles

21
Preventing Obesity in Adults

• Most likely to occur between ages of 25 and 34
• Regular, vigorous activity may prevent or lessen
  weight gain at any age
• Accept and acknowledge that people come in all
  sizes and shapes

22
Some people are underweight

• Worldwide, underweight is more common than
  obesity
• Underweight is more life-threatening
• Complex problem in developing nations
• In developed countries, causes include AIDS,
  cancer, illness, anorexia nervosa, and voluntary
  restriction of food

23
Defining underweight

• Women- less than 20 body fat
• Men- less than 12 body fat
• Less body fat in men or women loss of hormones
• Weights fall below ranges in table 9-2
• BMIs below acceptable range in Illus. 9-1
• Some people are genetically thin and healthy

24
Middle-Class Malnutrition

• Underweight caused by low-calorie, low fat diets
• Some parents restrict childrens intake so they
  wont become obese
• 2 of adolescents restrict their own intake so
  they wont become obese
• Different from anorexia or
  bulimia- goal is to stop weight
  gain, not lose weight

25
A Realistic View of Body Weight

• People naturally come in different sizes and
  shapes
• Half of all women in U.S. wear size 14 to 26
• Many clothing models are underweight
• Many men will never have a washboard
  stomach

26
Of all the things society can do to prevent
obesity, acceptance of people of different sizes
and a more realistic view of obtainable body
weights and shape may be two of the most
important.