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Obesity and Weight Control

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Title: Obesity and Weight Control


1
Obesity and Weight Control
  • Exercise Physiology
  • McArdle, Katch, Katch
  • Chapter 16

2
Overweight and Obesity
  • Overweight body weight that exceeds some average
    for stature, perhaps age.
  • Overfat body fat that exceeds an age- and/or
    gender appropriate average by some amt.
  • Obesity overfat condition that accompanies
    components of obese syndrome.

3
Obese Syndrome Components
  • Glucose intolerance
  • Insulin resistance
  • Dyslipidemia
  • Type 2 diabetes
  • Hypertenision
  • Elevated plasma leptin concentration
  • Increased visceral adipose tissue
  • Increased risk of CHD some cancers

4
Obesity A Global Epidemic
  • Why is obesity accelerating in developing
    countries?
  • Increased consumption of energy-dense, nutrient
    poor foods combined with reduced physical
    activity.

5
Obesity A Global Epidemic
  • What is the prevalence of overweight and obesity
    in the United States? 66 31

obesity trend
6
Obesity Trends Among U.S. Adults BRFSS, 1990,
2000, 2010
(BMI ?30, or about 30 lbs. overweight for 54
person)
2000
1990
2010
No Data lt10 1014
1519 2024 2529
30
7
Causes of Obesity
  • Obesity is a long term process.
  • Obesity frequently begins in childhood. Obese
    parents likely have overweight children.
  • Regardless of final body weight as adults,
    overweight children exhibit more illnesses as
    adults than normal kids.

You gonna finish that?
8
Causes of Obesity
  • Excessive fatness also develops slowly through
    adulthood, most weight gain occurring between
    ages 25 to 44 yrs.
  • Typical American man woman gain .5 to 1.8
    lb/year until 60.

9
Causes of Obesity
  • Overeating and Other Factors
  • Factors that cause human obesity
  • genetics, environmental, metabolic, behavioral,
    social
  • Factors that predispose a person to gain
    excessive weight gain.
  • Eating patterns Eating environment
  • Food packaging Food availability
  • Body image Physical inactivity
  • Basal body temp Dietary thermogenesis
  • Fidgeting Biochemical differences
  • Quantity sensitivity to satiety hormones

10
Overeating and Other Factors
  • Nutrition transition shifts in dietary structure
    toward higher energy density with greater fat and
    added sugars, greater saturated fat, reduced
    complex CHO and fiber, and reduced fruits
    vegetables.
  • Food consumption expressed in kCal per capita per
    day has increased.
  • Decreased energy expenditure for all populations
    of the world.

11
Causes of Obesity
  • Characteristics of fast food linked to increased
    adiposity
  • Higher energy density
  • Greater saturated fat
  • Reduced complex carbohydrates fiber
  • Reduced fruits and vegetables.

12
Causes of Obesity
  • Genetics plays a role.
  • How much variation in weight gain among
    individuals can be accounted for by genetic
    factors?
  • Familial association is not proof of genetic
    inheritance-families share eating exercise
    habits.
  • Largest transmissible variation is cultural.

13
Causes of Obesity
  • A Mutant Gene?
  • What is leptin?
  • A satiety hormone that influences the appetite
    control in the hypothalamus.
  • A defective gene may cause inadequate leptin
    production.
  • The brain receives an under assessment of bodys
    adipose stores urge to eat.

14
Causes of Obesity
Normally leptin blunts the urge to eat when
caloric intake maintains ideal fat stores. In
essence, leptin availability, or its lack,
affects the neurochemnistry of appetite and the
brains dynamic wiring to possibly impact
appetite and obesity in adulthood. Leptin alone
does not determine obesity or explain why some
people eat whatever they want and gain little
weight while others become overfat with the same
caloric intake.
15
Causes of Obesity
  • A defective ob gene causes inadequate leptin
    production. Thus, the brain receives an under
    assessment of bodys adipose stores and urge to
    eat.
  • May be defective leptin receptor action.
  • How does Leptin affect body fat?
  • Stimulates chemicals that suppress appetite
  • Reduce levels of chemicals that stimulate
    appetite.

16
Causes of Obesity
  • Physical Inactivity an important component
  • Each hour increase in TV by adolescents 2
    increase obesity.
  • Adults 15 over spent average 2.73 hr/day
    watching TV in 2010.
  • Each hour increase in TV by adults increase risk
    of death 11.

17
Obesity
  • Health Risks of Obesity
  • Primary risk factor for coronary heart disease.
  • Associated with HTN, DM, dyslipidemia,
    cerebrovascular disease.
  • Obesity-related medical complications account for
    10 of national health care.

18
Obesity
  • How Much Fat is TOO Much?
  • List three criteria for evaluating a persons
    level of fatness.
  • Body Fat
  • Fat Patterning
  • Fat Cell Size and Number

19
Percent Body Fat
  • Overfatness corresponds to any body fat value 5
    above the average value for age sex.
  • Borderline obesity in young man gt 20 in young
    woman gt30.

20
Fat Patterning
  • Adipocytes from some locations (gluteal
    femoral) efficiently capture excess nutrients
    from the blood-stream for storage, while others
    accumulate TGs but readily release them for use
    by other tissues.

21
Fat Patterning
  • Visceral (intra-abdominal) adipose tissue (VAT)
    relates to an altered metabolic profile.
  • Abdominal fat described as android (apple) has
    higher health risk than gynoid (pear) obesity.

22
Fat Patterning
  • Give an objective standard for establishing male-
    and female-pattern obesity.
  • Male gt .95 WH ratio
  • Female gt .80 WH

23
Fat Cell Number and Size
  • Increases in adipose tissue occurs in two ways
  • Fat cell hypertrophy
  • Fat cell hyperplasia

24
Fat Cell Number and Size
  • After reaching a biological upper limit for fat
    cell size, cell number becomes a key factor that
    determines obesity.

25
Weight Control
  • What is the prognosis for long term weight
    control?
  • Participants who remain in supervised weight loss
    program regain almost all within 5 years.

26
Weight Control
  • One pound of fat contains 3,500 kcal
  • Unbalance the Energy Equation (First Law
    Thermodynamics)
  • Reduce kcal intake
  • Increase kcal output
  • Reduce intake and increase output

27
Altering the Energy Balance
  • Total energy intake (not macronutrient mixture)
    determines effectiveness of weight loss with
    diet.
  • Rapid weight loss during first few days comes
    mainly from body water loss and glycogen
    depletion.
  • Continued weight reduction occurs at expense of
    greater fat loss per unit weight loss.

28
Altering the Energy Balance
  • Resting Metabolic Rate Lowered.
  • Blunted metabolism conserves energy causing diet
    to become progressively less effective.
  • Could lead to difficulty losing weight.

29
Fat Cell Size and Number
  • What happens to fat cell size and fat cell
    number when adults lose weight?
  • Fat cells shrink to a smaller size than
    adipocytes of nonobese people, number remains
    same.
  • The large of relatively small adipocytes may
    relate to appetite control person craves food,
    overeats gains lost weight.
  • Total number of fat cells increases 3 general
    periods
  • Last trimester pregnancy, 1st year life,
    adolescence

30
Fat Cell Size and Number
  • In non-obese subjects with moderate weight gain,
    adipocyte size increased substantially with no
    change in cell number.
  • Weight gain among severely obese, new adipocytes
    develop in addition to hypertrophy of existing
    cells.

31
Select a Diet Program
32
Exercising to Tip Energy Balance
  • Increased physical activity combined with dietary
    restraint maintains weight loss more effectively
    than caloric restriction alone.
  • For previously sedentary, overweight, moderate
    increases in physical activity do not necessarily
    increase food intake.
  • Recommend minimum of 3 days per week. Intensity
    individualized, minimum 300 kcal/session

33
Diet Plus Exercise
  • Combining exercise and diet offers more
    flexibility for weight loss.
  • Exercise facilitates fat mobilization from
    adipose depots and fat catabolism. Preserves fat
    free body mass, blunts decrease in RMR, improves
    insulin sensitivity.

34
Diet Plus Exercise
  • The Ideal Combination
  • Exercise enhances fat mobilization from bodys
    adipose depots and fat catabolism by active
    muscles.
  • Protects against protein loss in skeletal muscle
    and improves insulin sensitivity.

35
Maintenance of Goal Body Weight
  • Most weight loss occurs during first 6 months. Up
    to 85 those starting a weight loss program drop
    regain.
  • IOM recommend that obese reduce initial body
    weight by 5 to 15 as realistic.

36
Maintenance of Goal Weight
  • Selective fat reduction at specific body areas by
    spot reduction does NOT work.
  • Exercise stimulates fatty acid mobilization
    through hormones and enzyme action that target
    fat depots throughout the body.

37
Gaining Weight
  • Resistance training complemented by well-balanced
    diet increases muscle mass.
  • If all calories consumed in excess of energy
    requirement during resistance training would go
    towards muscle growth, 2000 to 2500 extra
    calories would support 0.5 kg increase in lean
    tissue.
  • Intense aerobic training will detract from
    maximal increases in muscle mass.

38
Conclusions
  • When traveling in Oia, Santorini a Greek Island,
    EAT, DRINK, and BE HAPPY, for tomorrow you may
    die.
  • If you make it home, exercise often, hard, and a
    long time.

39
Illustration References
  • McArdle, William D., Frank I. Katch, and Victor
    L. Katch. 2000. Essentials of Exercise
    Physiology 2nd ed. Image Collection. Lippincott
    Williams Wilkins.
  • Plowman, Sharon A. and Denise L. Smith. 1998.
    Digital Image Archive for Exercise Physiology.
    Allyn Bacon.
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