Obesity

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Obesity Body Composition
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Physical Activity
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Physical Activity

• Larger individuals burn more calories for the
  same activity
• 100 kcals/mile walking, running or swimming
• 50-80 kcals/mile for cycling

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Physical Activity
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Physical Activity

• CDC
• Moderate-intensity physical activity generally
  requires sustained rhythmic movements and refers
  to a level of effort equivalent to
• A "perceived exertion" of 11 to 14 on the Borg
  scale
• 3 to 6 metabolic equivalents (METs)
• Any activity that burns 3.5 to 7 Calories per
  minute (kcal/min) or
• The effort a healthy individual might expend
  while walking briskly, mowing the lawn, dancing,
  swimming, or bicycling on level terrain, for
  example.
• A person should feel some exertion but should be
  able to carry on a conversation comfortably
  during the activity.

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Physical Activity

• Exercise alone can lead to weight loss
• However, it is insufficient for long-term weight
  loss
• Exercise and caloric restriction is more
  effective
• Exercise does help offset lean muscle mass loss
  from low calorie diets
• Unknown how physical activity affects food intake

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Physical Activity -Endurance Training

• A single session of exercise may only burn 300
  calories
• However, 3-4 times a week over a year will result
  in a loss of 13-23 pounds
• As fitness level improves, exercise may be more
  effective
• Improved fat metabolism during exercise
• Increase resting metabolic rate

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Physical Activity Weight Training

• Fewer calories are burned per minute compared to
  endurance exercise
• Greater increase in muscle mass and resting
  metabolic rate
• Isnt as effective as endurance exercise even
  when combined with dieting
• Cant spot reduce

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Physical Activity - Spot Reduction

• Cant happen.
• Fat cell and muscle cells are not directly
  connected.
• Hormones that mobilize lipids dont work on
  individual cells.
• Lower body fat is more resistant fat compared
  to upper body fat.

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Physical Activity - Misconceptions

• 1. Exercise increases food intake
• 2. Few calories are burned during exercise

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Physical Activity

• Higher metabolic rate
• Better insulin control
• Dose-response relationship
• Guidelines
• Start slowly
• Consistency
• Duration over intensity
• Resistance training

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Physical Activity - Exercise

• 1500 kcals/week as a minimum
• Most effective with 200-300 minutes of physical
  activity per week
• Exercise intensity for increasing RMR
• Cant spot reduce
• Post-exercise caloric cost will add 15-50
• Exercise plus diet is more effective than diet
  for maintaining weight loss
• Diet alone can decrease RMR up to 30

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Successful weight loss maintenance.Author Wing,
Rena R. Hill, James O. Source Annual Review of
Nutrition v. 21 (2001) p. 323-41
SUMMARY   Successful weight loss intentional
weight loss of greater than or equal to 10 of
initial body weight that is maintained at least 1
year be considered success. According to this
definition, approximately 20 or more of
individuals who attempt weight loss would be
"successful." Although the National Weight
Control Registry (NWCR) does not provide
information about how many people achieve
long-term weight loss success, it does provide
information about strategies used to achieve and
maintain a weight loss. With regard to weight
loss, the most obvious conclusion from the NWCR
is that weight loss should include both changing
diet and increasing physical activity. We do
not, however, see any particular type of diet
modification to achieve the weight loss that is
common to these successful weight loss
maintainers.
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We believe that strategies for weight loss
maintenance may be the key to long-term weight
management success. We find three behaviors in a
vast majority of NWCR subjects. First, these
subjects engage in high levels of physical
activity (1 hour per day) Second, these subjects
report eating a diet low in fat and high in
carbohydrate. Third, these subjects report
regular self-monitoring of weight. Currently,
the data seem to suggest that differences in
behavior are stronger predictors of weight regain
than the differences in physiology or
metabolism. Part of the reasons for developing
the NWCR was to counter the belief that "no one
succeeds long-term at weight loss." We believe
the subjects in the NWCR show that you can
achieve and maintain substantial amounts of
weight loss. Furthermore, we have found that
these subjects live "normal" lives after weight
loss and consistently report that life is better
after weight loss. Our subjects tell us that
their success requires substantial effort but
that it is worth it. Finally, our data suggest
that over time, it does get easier to maintain
weight loss. It may be a lifelong struggle, but
once you have maintained a weight loss for 2-5
years, the chances of longer-term success greatly
increase.
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Physical Activity and Diet

• Goal. Lose 1 pound per week
• Require 500 calorie deficit per day
• Walking or jogging 5 miles a day
• Or, walk/jog 2.5 miles a day and eat 250 less
  calories per day.
• However, if burn 500 calories a day and eat 250
  less a day, lose 1.5 pounds per week.

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Physical Activity - Weight Control

• Obesity is not simple a problem of gluttony
• Caloric intake per person has decreased for the
  past 100 years

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Behavior Modification

• Self-monitoring patterns of eating and exercise
• Stimulus control controlling the environment
• Reinforcement rewards
• Nutrition - knowledge
• Exercise and physical activity
• Social support
• Cognitive change - attitudes

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Eating Disorders
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Eating Disorders

• Anorexia nervosa
• Bulemia nervosa
• Binge eating

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Eating Disorders
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Anorexia Nervosa

• Individuals who have anorexia nervosa do not eat
  enough food to maintain a reasonable body weight,
  and they have an intense fear of getting fat.
  They engage in compulsive behaviors to keep from
  eating and commonly use prolonged exercise to
  reduce body weight.
• Anorexia affects 13 million Americans, 90 of
  whom are women, and it typically occurs between
  the ages of 12 and 18.
• Medical complications include disorders of the
  cardiovascular, gastrointestinal, and endocrine
  systems cessation of menstruation and even
  death from heart failure.

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Bulemia Nervosa

• This disorder is characterized by binge eating
  from 100060,000 calories and then purging
  through vomiting and/or the use of laxatives or
  diuretics.
• The strain on the body is enormous, and the
  health effects include tooth decay, esophageal
  damage, chronic hoarseness, menstrual
  irregularities, depression, liver and kidney
  damage, and cardiac arrhythmia.

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Binge Eating

• Characterized by uncontrolled eating without
  purging, binge eating often results in weight
  gain and feelings of guilt, shame, and
  depression.
• Individuals with binge-eating disorder do not eat
  because they are hungry rather, they eat as a
  coping mechanism for stress, conflict, and
  emotional difficulty.

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Weight Loss

• Accurate assessment of body composition (not
  society)
• Eat less fat and less high glycemic index foods
• Aerobic exercise emphasizing duration
• Resistance exercise with proper rest
• Patience and realistic

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Body Composition
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Classification of Obesity

• CDC
• Percent body fat
• Greater than 25 for men
• Greater than 33 for women

Dr. Emmett. Spring Break 2003
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Criteria for Obesity

• Men greater than 20
• Women greater than 30

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Body Mass Index

• kg/m2
• Health risks
• Moderate less than 20
• Very Low 20-25
• Low 25-30
• Moderate 30-35
• High 35-40

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Body Mass Index and Waist Circumference
Disease risk relative to normal weight and waist
circumference
Men 40 Women 40 -- -- -- -- Inc
rease High High Very High Very High Very
High Extremely high Extremely high
Note Research suggests that a low BMI can be
healthy in some cases, as long as it is not the
result of smoking, eating, disorder, or an
underlying disease process.
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Waist to Hip Ratio

• Waist/hip circumference
• Very high risk if greater than 0.82 for women and
  0.90 for women over 60
• Very high risk if greater than 0.94 for men and
  1.03 for men over 60
• Android (apple)
• Gynoid (pear)
• Which is most unhealthy?
• Android
• Why?
• Fat release directly into portal vein and
  to the liver which stimulates cholesterol
  production

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Regional Fat Distribution

• Central or Android or Apple
• Peripheral or Gynoid or Pear
• Ratio limits
• 0.8 for women
• 0.95 for men
• Lipoprotein Lipase

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Body Composition

• Fat mass
• Fat-free mass
• Bone
• Water
• Muscle
• Organs

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Desirable Body Mass

• Brooks,Fahey, White, and Baldwin
• Men less than 20
• Women 16-25
• McArdle, Katch and Katch
• Men 15
• Women 25
• ACSM 50th percentile (20-29 up to 60)
• Men 15.9 to 23.5
• Women 22.1 to 30.9
• Fahey, Insel, and Roth (Acceptable)
• Men 12-20
• Women 20-30
• Jackson and Pollack (Average for 20-29 year olds)
• Men 14-20
• Women 20-28

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Measuring Body Composition

• Dissection

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Hydrostatic Weighing

• Which weighs more, a pound of fat or a pound of
  muscle?
• Which is more dense, a pound of fat or a pound of
  muscle?
• Why the difference?

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Hydrostatic Weighing

• Archimedes and King Hieron
• Arch knew that density mass / volume
• Arch knew the mass of the crown
• Volume mass on land - mass in water
• Arch underwater weighed gold and silver each with
  the same mass as the crown
• However, the volume for the gold was different
  from the crown.
• Eureka, the crown is a fraud.

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Hydrostatic Weighing

• Assumptions
• FFM density is 1.1 g/ml
• Fat mass 0.902 g/ml
• Theory
• Fat has a different density from Lean Body Mass
• Density Mass / Volume
• UWW determines volume
• Dry weight minus Under water weight volume
• With volume and mass can calculate body density
  (Db)
• Siri or Brozek equation converts Db to BF

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Hydrostatic Weighing

• Errors
• Equations
• Residual lung volume
• Water density
• Consistency of tissues across races, gender, age
• Recommended Technique.
• Water tank
• Nitrogen wash out
• Weight belt
• Maximal exhalation
• Repeat 8-12 times
• r 0.94

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Dr. Emmett
Dr. Pritschet
BP
JE
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Hydrostatic Weighing

• Example. A person weighs 75 kg in air and 3 kg in
  water.
• 72 kg of water was displaced
• 72 kg of water 72 liters or 72,000 cm3
• Therefore the density would equal 75 kg / 72,000
  cm3, or 1.0416 g/cm3
• So?

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Hydrostatic Weighing

• D F L / (F/f) (L/l)
• Too complicated?
• Body fat (495 / D) - 450
• This is the Siri equation.
• Brozek (457/Db) 4.142
• If all measurements are correct, it has a 1
  margin of error for body fats between 4 and 30.

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Hydrostatic Weighing

• Advantages?
• Good accuracy
• Disadvantages?
• Water
• Costs

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Duel-Energy X-Ray Absorptiometry (DEXA)

• Developed to measure bone density
• Can measure bone, non-bone, and fat density
• New gold standard?
• Comparison
• Error 1-5
• Software
• Body sections differences
• Very costly
• Very high tech
• Quick, subject friendly

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Biochemical Techniques

• Potassium
• Constant proportion within muscle mass.
• Total Body Water
• Deuterium, heavy water, etc.
• FFM TBW (L)/0.732
• Fat Soluble Inert Gas Absorption
• Accurate but expensive

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Skin folds

• Theory. Relationship between fatfolds and total
  fat mass
• Fat folds used to determine density.
• Density used to estimate percent body fat.
• Assumptions

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• 1. All measurements should be taken from the
  right side of the body. The skinfold site should
  be marked with a black felt tip pen.
• 2. Pick up the skinfold with you left the index
  finger and thumb. Be sure you have two layers of
  skin and the underlying fat. To make sure it is a
  true skinfold and not muscle, check by having the
  subject contract the underlying muscle as you are
  grasping the skin - and then relax before taking
  a reading.
• 3. The calipers should be held in the right hand
  perpendicular to the fold, with the dial face up
  and easy to read. The calipers should be place
  1/4 to 1/2 inches away from the fingers holding
  the skinfold , so that the pressure of the
  calipers will not be affected.
• 4. Apply the calipers about 1 cm. below the
  fingers. It should be applied where the two
  surfaces of the folds are parallel. Do not apply
  the calipers where the fold is rounded near the
  top, or where it is broader near its base. Keep
  holding the skin as measures are read.
• 5. Measure all skinfolds to the nearest 0.5 mm as
  you continue to grasp the skin. Measure one site
  once, then the next site once and so on until you
  have measured all sites once. Then repeat the
  cycle a minimum of three times at each site. Use
  the average of the scores at each site for the
  final skinfold score. If there is a question as
  to the accuracy of the measure, discard that
  measure and remeasure. The measurements at each
  site should be within 5 percent accuracy, i.e.,
  if the first measurement is 20 mm., the second
  measurement should be 20 or - 1 (0.5 X 20 1).
  The person who is measuring should not know the
  results of the first measurement when taking the
  second and so on.
• 6. During the measurement, constant pressure must
  be maintained by the thumb and forefinger.
• 7. Measurements should not be taken under the
  following conditions When the skin is moist or
  wet, after exercise, or when the subject is
  overheated, because these conditions will cause
  larger skinfolds and, consequently, larger
  values.

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Skin folds

• Calipers
• constant tension
• true double layer
• two seconds
• Sites
• right side of the body
• minimum of 2 locations
• exact locations

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Skin folds

• Measurements sum of fat folds and percent body
  fat.
• Advantages cheaper, quicker, comfort, mobile
• Disadvantages obese, experience, equation,
• 3-5 error

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Skin Fold Equations

• Females
• Db 1.0994921 - (0.0009929 X sum of 3 SKFs)
  (0.0000023 X sum of 3 SKFs2) - (0.0001392 X
  age).
• Males
• Db 1.0938 - (0.0008267 X sum of 3 SKFs)
  (0.0000016 X sum of 3 SKFs2) - (0.0002574 X
  age).
• Siri Percent fat 4.95 - 4.50 X 100
                              Db
• Brozek Percent fat 4.570 - 4.142 X 100
                                     Db

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Bioelectrical Impedance

• Assumptions
• Fat-free mass 73.2 water
• UWW is accurate

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Bioelectrical Impedance

• Theory.
• Human body is 67 to 74 water
• Adipose tissue has far less water than other
  tissues
• FFM low resistance to electrical flow where FM
  high resistance.
• Technique

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Bioelectrical Impedance

• Advantages quick, easy, cost?,
• Disadvantages differences in equipment, body
  water level, skin temp, equations,

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Other Techniques

• CT scan, MRI, DEXA
• Bod Pod
• under air weighing
• air displacement
• Ultrasound - thickness
• X-ray - thickness

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Air Plethysmography (Bod Pod)
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Air Plethysmography (Bod Pod)

• Similar principle as UWW only it uses air instead
  of water
• Comparison
• Error 2-3
• Costly
• Convenient for subject
• Low tech skills