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