Transcript Chapter 11: Water and the Major Minerals

Energy Balance and
Weight Control
Obesity is a Growing
Problem
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127 million adults in the U.S. are
overweight, 60 million obese, and 9
million severely obese.
64.5 percent of U.S. adults are
overweight (BMI≥25)
30.5 percent are obese (BMI≥30)
4.7 percent are severely obese
(BM≥40)
Obesity Trends* Among U.S. Adults
BRFSS, 1985
Source: Mokdad A H, et al. J Am Med Assoc 1999;282:16,
2001;286:10.
Obesity Trends* Among U.S. Adults
BRFSS, 2001
Source: Mokdad A H, et al. J Am Med Assoc 1999;282:16,
2001;286:10.
Prevalence of Obesity in
Ohio
25
20
15
% of adults
10
5
0
1991
1995
1998
1999
2000
2001
Obesity: A Major Health
Issue
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Obesity is the No. 2 preventable cause of
death and disability (smoking is #1)
Obesity is associated with increased risk of
heart disease, stroke, gallbladder disease,
cancer, osteoarthritis, sleep apnea
Obesity-related health problems cost $75
billion annually (2003 data)
The public pays about $39 billion a year -or about $175 per person -- for obesity
through Medicare and Medicaid programs
Health Risks of Obesity
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Cardiovascular disease
Cancer
Hypertension
Bone/joint disorders
Type 2 diabetes
Energy Balance
Relationship between energy intake and energy
expended
 Positive energy balance
– Energy intake > energy expended
– Results in weight gain
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Negative energy balance
– Energy intake < energy expended
– Results in weight loss
Estimating Kcal Content
in Food
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Bomb calorimeter
Burns food inside a
chamber surrounded by
water
Heat is given off as food
is burned
The increase in water
temperature indicates
the amount of energy in
the food
Use and Storage of Fat
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Most fat is stored directly into adipose
tissue
Body has unlimited ability to store fat
(as fat)
Fat will remain as fat for storage
Physical activity encourages the
burning of dietary fat
Use and Storage of CHO
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Limited CHO can be stored as glycogen
Most CHO is used as a energy source to
meet immediate energy needs
Excessive CHO will be converted to fat (for
storage)
Body prefers to use CHO as energy source
Only excess intake of CHO and protein will
be turned into fat
Use and Storage of
Protein
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Protein is primarily used for tissue
synthesis
Excess protein is used for energy
Some protein will be synthesized into
fat (for storage)
Protein cannot be stored as protein
Energy In Vs. Energy Out
NEAT
Basal Metabolism
Dietary Intake
Physical Activity
Thermic Effect of food
Basal Metabolism
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The minimum energy expended to
keep a resting, awake body alive
~60-70% of the total energy needs
Includes energy needed for
maintaining a heartbeat, respiration,
body temperature
Amount of energy needed varies
between individuals
Approximately 0.9 kcal/kg/hr
Estimate Basal Metabolism
Female: Wt (kg) x 0.9 kcals/hour x 24
50 kg (110 lb) x 0.9 x 24 =
1080 kcals
Male:
Wt (kg) x 1 kcal/hour x 24
100 kg (220 lb) x 1 x 24 =
2400 kcals
Calculate Your BMR
________ x ______ x
24
= ____ kcals/day
This is only an
estimate!!
Factors that Increase
Basal Metabolism
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Body surface area (weight, height)
Male gender
Body temperature
Thyroid hormone
Nervous system activity
Kcal intake
Pregnancy
Use of caffeine and tobacco
Factors that Decrease
Basal Metabolism
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Age
– – 2% drop each decade after 30
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Low calorie diet
– 10-20% decrease
Physical Activity
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Increases energy expenditure beyond
BMR
Varies widely among individuals
More activity, more energy burned
Lack of activity is the major cause of
obesity
Thermic Effect of Food
(TEF)
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Energy used to digest, absorb, and
metabolize food nutrients
“Sales tax” of total energy consumed
~5-10% above the total energy
consumed
TEF is higher for CHO and protein than
fat
Less energy is used to transfer dietary
fat into adipose stores
Nonexercise Activity
Thermogenesis (NEAT)
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Nonvoluntary physical activity
triggered by overeating
Fidgeting
Maintenance of muscle tone
Maintenance of posture
Overeating increases sympathetic
nervous system activity
Resists weight gain
Measurement of Body’s
Energy Needs
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Direct calorimetry
– Measures heat output from the body
using an insulated chamber
– Expensive and complex
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Indirect calorimetry
– Measures the amount of oxygen a person
uses
– A relationship exists between the body’s
use of energy and oxygen
Food Guide Pyramid
Energy Estimates
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1600 kcals – sedentary women, some
older adults
2200 kcals – Children, teen girls,
active women, most men
2800 kcals – teen boys, active men,
very active women
Food Guide Pyramid
Calorie Estimates
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Sedentary: 25-30 kcal/kg
Moderate activity: 35 kcal/kg
Heavy activity: 40 kcal/kg
Energy Needs from US
Dietary Guidelines
What is a Healthy Body
Weight?
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Based on how you feel, weight history,
fat distribution, family history of
obesity-related disease, current health
status, and lifestyle
Current height/weight standards only
provide guides
A Healthy Body Weight
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What is the lowest weight maintained
for more than a year as an adult?
What weight was maintained without
constantly feeling hungry?
Establish a “personal” healthy weight
Body Mass Index (BMI)
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The preferred weight-for-height
standard
Calculation:
Body wt (in kg)
[Ht (in m)]2
OR
Body wt (in lbs) x 703.1
[Ht (in inches)]2
Health risks increase when BMI is > 25
BMI is Not a Measure of
Body Fatness
Height 6'3"
Weight 220 lbs
BMI 27.5
Height 6'3"
Weight 220 lbs
BMI 27.5
BMI Does Not Measure
Body Fat
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However, most people
with high BMIs are
overfat
BMI and Health
Below 18.5
Underweight
18.5 – 24.9
Normal
25.0 – 29.9
Overweight
Monitor for risk
Obese
Increased health risk
Severely obese
Major health risk
30.0 and Above
40.0 and above
Overweight (BMI 25-30)
Monitor for
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Hypertension
Elevated LDL-cholesterol
Family history of obesity, CVD, certain
cancers
Pattern of fat distribution
Elevated blood glucose: diabetes,
insulin resistance
Perspective on Weight
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Unrealistic goals
Listen to body’s cues (for hunger)
Eat a healthy diet
Physical activity
“Size acceptance”
Obesity
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Excessive amount of body fat
– Women with > 35% body fat
– Men with > 25% body fat
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Increased risk for health problems
Are usually overweight, but can
have healthy BMI and high % fat
Measurements using calipers
Estimation of Body Fat
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Underwater
weighing Most
accurate
– Fat is less dense
than lean tissue
– Fat floats
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Problems with
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Children
Elderly
Very large
Fear of water
Estimation of Body Fat
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Bioelectrical impedance
– Low-energy current to the body that measures the
resistance of electrical flow
– Fat is resistant to electrical flow; the more the
resistance, the more body fat you have
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DEXA (dual x-ray photon absorptiometry)
– An X-ray body scan that allows for the
determination of body fat
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Infrared light
– Assess the interaction of fat and protein in the
arm muscle
Skinfold Thickness
Accurate with
 Training
 Good calipers
 Multiple sites
 Multiple
measurements
Health Problems Associated
with Excess Body Fat
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Surgical risk
Lung (pulmonary)
disease
Sleep apnea
HTN
CVD
Bone and joint
disorders (gout,
osteoarthritis)
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Gallstones
Cancers (breast,
colon, pancreas,
gallbladder)
Infertility
Pregnancy- difficult
delivery
Reduced agility
Early death
Desirable % Body Fat
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Men: 8-25%
Women 20-35%
Body Fat Distribution
Upper-body (android) obesity--apple
shape
 Associated with more heart disease,
HTN, Type II Diabetes
 Abdominal fat is released right into the
liver
 Encouraged by testosterone and
excessive alcohol intake
 Defined as waist measurement of > 40”
for men and >35” for women
Body Fat Distribution
Body Fat Distribution
Lower-body (gynecoid) obesity--Pear
shape
 Encouraged by estrogen and
progesterone
 After menopause, upper-body obesity
appears
 Less health risk than upper-body
obesity
Juvenile-Onset Obesity
Develops in infancy or childhood
 Increase in the number of
adipose cells
 Adipose cells have long lifespan
and need to store fat
 Makes it difficult to lose the fat
(weight loss)
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Adult-Onset Obesity
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Develops in adulthood
Fewer (numbers of) adipose cells
These adipose cells are larger (store
excess amount of fat)
If weight gain continues, the number
of adipose cells can increase
Causes of Obesity
Nature vs Nurture
 Identical twins raised apart have similar
weights
 Genetics account for ~40%-70% of weight
differences
 Genes affect metabolic rate, fuel use, brain
chemistry, body shape
 Thrifty metabolism gene allows for more fat
storage to protect against famine
Nature vs Nurture
Obesity tends to run in families
 If both parents are normal weight –
10% chance of obesity in offspring
 If one parent is obese – 40% chance
 If both parents obese – 80% chance
Is it genetics or learned eating behavior?
Causes of Obesity
Nurture debate
 Environmental factors influence weight
 Learned eating habits
 Activity factor (or lack of)
 Poverty and obesity
 Female obesity is rooted in childhood
obesity
 Male obesity appears after age 30
Nature and Nurture
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Obesity is nurture allowing nature to
express itself
Location of fat is influenced by genetics
A child of obese parents must always be
concerned about his weight
Nature and Nurture
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The influence of
environment is apparent
in the fact that the
prevalence of obesity
has increased
dramatically in the US in
the past 40 years
Nurture Theory
Eating habits
 Overeating learned early in childhood
 Bottle vs breast
 Urging children to eat more, clean
their plates
 Use of food as a reward
Food = Love
Shelly Thorene Photography
Eating Response to NonHunger Cues
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Boredom/depression/stress
Food availability
– Increases overeating
– Monotonous diet – eat less
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Media triggers
– Constant advertisements
– Attractive foot
Activity Habits
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U.S. Physical
activity declining
– Work
– Leisure
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U.S. obesity rising
2005 U.S. Dietary
Guidelines: Activity
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To reduce the risk of chronic disease in
adulthood: engage in at least 30 minutes of
moderate-intensity physical activity…on most
days of the week
To help manage body weight, engage in…60
minutes of moderate to vigorous intensity
activity on most days of the week
To sustain weight loss in adulthood:
participate in at least 60-90 minutes of daily
moderate-intensity physical activity while not
exceeding calorie requirements
2005 U.S. Dietary
Guidelines: Activity
However Exercise Alone is Generally Ineffective in Taking Weight Off!!
Nature Vs. Nurture
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Those at risk for obesity will face a
lifelong struggle with weight
Gene does not control destiny
Increased physical activity, moderate
intake can promote healthy weight
Set Point Theory
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Weight is closely regulated by the body
Genetically predetermined body weight
Body resists weight change
Leptin assists in weight regulation
Weight returns after weight loss
Reduction in energy intake results in lower
metabolic rate
Ability to shift the set point weight