Transcript Slide 1

Unit 9
Body Weight
Units 9 and 10 are not assigned
reading. You are only
responsible for material in the
powerpoint and lecture.
Key Concepts and Facts
 Ideal weight and shape should be based on
health
 Rates of overweight and obesity increasing
world-wide
 Disease and disorders related to body fat
increasing
 Location and amount of body fat stores
important to health
Key Concepts and Facts
 Causes of obesity are complex
 Influences on development
 Diet
 Physical activity
 Environmental exposures
 Genetic factors
 We need to understand calorie need and
balance intake with expenditure.
Body Weight Variations
 Regulation of food intake and storage is a very
old genetic trait
 Underweight was a disadvantage for our remote
ancestors
 Intake and fat storage were keys to survival
 Changes in availability of food can explain why
obesity is a major problem
Weight Status Defined?
Culture defines
reaction to body
size
Europe of 1400s:
pear-shaped adults
were beautiful
Some cultures still
consider extra fat
sign of health and
beauty
Weight Status Defined?
Today - thinness
beyond health
boundaries is the
standard of beauty
• “Too thin” is the
cultural ideal
• Men feel visible
body fat is
culturally taboo
Body Mass Index
 BMI is a measure of weight for height to estimate
body fat
 Ranges of BMI define weights for height
–
–
–
–
Underweight
Normal weight
Overweight
Obese
 BMI calculation same for males and females
BMI = [Weight(lbs)]*[703]/[height(in)]2
BMI = [Weight(kg)]/[height(m)]2
BMI
 Underweight < 18.5
 Normal weight 18.5-24.9
 Overweight
25-29.9
 Obese
30 or more
US Adults Too Heavy
 Overweight and obesity is at 67% and rising

for adults
 Obese children aged 6–11 increased from
 Under 5% in 1965, 7% in 1980,
 Nearly 18% in 2012.
 In 2012, more than one third of children and
adolescents were overweight or obese.
 Obesity is our #1 health problem.
% Obesity by States
World-wide Problem
 High rates of obesity becoming more
common worldwide
 Europe - 10-25% of adults are obese
 A billion adults worldwide are overweight
 Obesity is world public health problem
World Obesity Rates
Obesity and Health
 Obesity is not a healthy state
 Increased risk for:
– Diabetes
– Hypertension
– Stroke
– Heart disease
– Certain types of cancer
 Life expectancy in overweight/obese adults 3 to 6
years shorter than average
 Weight loss lowers blood pressure, LDL cholesterol,
risk of diabetes and increases HDL cholesterol
NIH study finds leisure-time physical activity
extends life expectancy as much as 4.5 years
 Leisure-time physical activity is associated with
longer life expectancy, even at relatively low
levels of activity and regardless of body weight,
according to a study by a team of researchers led
by the National Cancer Institute (NCI), part of
the National Institutes of Health. The study,
which found that people who engaged in leisuretime physical activity had life expectancy gains
of as much as 4.5 years, appeared Nov. 6, 2012,
in PLoS Medicine
BMI Shortcomings
 Weight-for-height and percent body fat do not
always correspond
 Muscular people can have “obese” BMI
 Inactive normal BMI people can still have too
much body fat
 If people retain fluid, BMI may show overweight
but body fat may be low
 Measures of body fat are more accurate than
weight-for-height
Assessing Body Fat
 Skinfold thickness measures
 Bioelectrical impedance analysis (BIA)
 Underwater weighing
 Magnetic resonance imaging (MRI)
 Computerized axial tomography (CT scans)
 Dual-energy X-ray absorptiometry (DEXA)
 Whole body air displacement (BOD POD)
Each one has advantages and drawbacks
Some Body Fat Needed
 3 to 5% for men and 10 to 12% for women needed for
survival
 Essential in manufacture of hormones
 Required component of every cell in the body
 Provides a cushion for internal organs
 Low body fat levels:
– delay physical maturation during adolescence
– Cause infertility
– accelerate bone loss
– Accompany starvation
Apples and Pears
Location Important
 Pear-shaped: store fat in hips and thighs
(better)
 Apple-shaped: store fat around the waist
(worse)
 Apple shape is more common among obese
men
 Obese young women more often "pears"
 Obese older women exhibit both shapes
Why “Apple” is bad
 Fat cells of central-body fat deposits are
larger than those around the hips and
“resistant” to insulin
 Decrease ability of insulin to lower blood
glucose
 Insulin and glucose increase over time
Increased Insulin
 increases triglyceride levels and blood
pressure
 reduces levels of HDL
increases risk of hypertension and
heart disease
promotes the development of
diabetes
Body Fat Distribution
 Waist size is stronger
predictor of heart disease,
stroke, and diabetes than
BMI (measure
horizontally!)
 Waist < 40 inches in men
or 35 inches in women
decreases risk of these
diseases
What Causes Obesity?
 Obesity occurs when calorie intake
exceeds caloric expenditure
 Cause is complex
– genetics
– environmental exposures
– diet
– physical activity
Heredity
 Genetics important in obesity
 Heredity is 25 to 40% of obesity risk
 FEW born with errors in metabolism
 MANY born with traits expressed after
some environmental trigger
Environmental Triggers
 Change from active lifestyle to sedentary
(off-season for athletes)
 Change from home-cooked meals at set
times to lots of empty calorie food
available
 Laid off: change from being busy to
at home alone with refrigerator
 Eating out more: large portion sizes served
Weight Gain and Environment
 Chinese Study
 Shows weight
changes when either a
bicycle or motorized
vehicle is acquired
 Three year study
Diet and Obesity
 Weight gain if
– energy in > energy out
 Caloric intake up by 340/day
 Excess fat, protein or carb ——>
increased body fat stores
 Type of calories not important
 Number of calories is!
Unit 10 WEIGHT CONTROL
Weight Control:
The Myths and
Realities
©2005 Thomson-Wadsworth
Key Concepts and Facts
 Effectiveness of weight-control methods
gauged by ability to prevent regain
 Because a weight-loss product or service is
widely publicized doesn’t mean it works
 Successful weight control characterized by
gradual weight loss
Distressed over Weight
 Americans spend over $33 billion annually
on weight-loss products and services
 Americans are gaining weight faster than
they are losing it
 Obesity in the United States is on the rise
 Only 5 to 10% of people who lose weight
keep it off for more than a year
Why We fail at weight loss
 A reduction in caloric intake produces weight
loss
 Fad methods fail, they become too unpleasant
 Hunger, deprivation, and depression lead to
regain
 Enjoyable eating and exercise habits are needed
to keep excess weight off
 Quick weight-loss approaches don’t change
habits
Weight Loss Business
 More than 29,000 weight-loss products
and services are available
 Most either don’t work at all or don’t
prevent weight regain
 “Quick fix” weight-loss approaches don’t
lead to long-term changes in behavior
 No laws require a product to be effective.
Truth in labeling Laws
 Laws do not keep outrageous claims off
television or from being printed in
pamphlets, books, magazines, and
advertisements
 Few companies get caught if they include
false or misleading information in weightloss product ads
Ephedra, or Ma Huang
 An over-the-counter diet pill and energy-booster
 A herbal product often in combination with caffeine
 Serious side effects are related to its use
– Hypertension
– Irregular heart beat
– Stroke
– Heart attack
– Seizure
– Sudden death
– Finally banned in 2004 after at least
155 deaths
High protein diets
 Help people lose weight
 Pose risks to health
 Do not help people maintain weight loss
 Promote loss by decreasing appetite
 Deprive body of carbohydrates
 Fats are used for energy instead
 Use of fat means increased “ketone bodies”
 Ketone bodies decrease appetite
High Protein Diet?
Protein Diet Limitations
 May cause faster weight loss in the first six
months of a diet
 By one year mark, weight loss is about the
same
 People revert to more pleasurable, usual
diets
 As soon as carbohydrates are returned to
the diet in normal amounts, appetite returns
and weight gain follows
Can They Lose It & Keep It
Off?
National Weight Control
Registry
Popular myth about weight loss:
everyone who loses weight will
eventually gain it back.
This research study has exploded this myth
Includes more than 5,000 individuals who have
lost significant amounts of weight
and kept it off for long periods of time.
National Weight Control
Registry
Founded in 1993 by
Dr. James Hill of the University of Colorado
Dr. Rena Wing of Brown University and University of
Pittsburgh.
Longitudinal prospective study of individuals 18 years
and older,
Successfully maintained a 30 pound weight loss for a
minimum of 1 year.
National Weight Control
Registry
 Successful weight losers report making substantial
changes in eating and exercise habits to lose weight
and maintain their losses.

 The average registrant has lost approximately 60
pounds and has maintained that loss for roughly 5
years.

* Two-thirds of these successful weight losers were
overweight as children and 60% report a family history
of obesity.
*Extensive histories of overweight and
failed dieting attempts
*Participants used diet and exercise to initially lose
weight
 *About half of registry members report that they
initially lost weight on their own
 *About half used a formal weight loss program
or assistance from a health care professional.
 *Both those who lost on their own and those in a
program are meeting RDAs for most nutrients
*
What led to success?
 Nearly every subject is currently using diet
and exercise to maintain his/her weight
 loss.
Walking is the most frequent physical
activity performed by NWCR
members.
 Weight loss led to significant
improvements in self-confidence, mood and
physical health.
National Weight Control
Registry
What’s different about them?
Compared to the general population,
are consuming less energy and a lower percentage of
energy from fat.
*Among this sample of successful weight loss
maintainers, maintenance of weight loss
is associated with continued consumption of a healthy
low-energy, low-fat diet.
Breakfast Consumption and Weight
Loss
*78% reported regularly eating breakfast every day of
the week.
*Only 4% reported never eating breakfast.
*No difference in reported energy intake between
breakfast eaters and non-eaters
*Breakfast eaters reported slightly more physical
activity than non-breakfast eaters
*Eating breakfast is a characteristic common to
successful weight loss maintainers and may be a factor
in their success.
Does weight loss maintenance become
easier over time?
Obesity Research, 8: 438-444.
For several health-related behaviors, risk of relapse seems to
decrease over time.
Registry members who had maintained weight losses for longer
periods of time said that less effort was needed to stay on a diet and
to maintain their current weight.
Members who had maintained weight losses for both shorter and
longer periods of time derived equal amounts of pleasure from
exercise, low-fat eating and maintaining their weight losses.
As duration of maintenance increases, the effort required to
maintain seems to decrease.
Enjoy Activity
The
End