Obesity-and-weight-control

1. Obesity and Weight
Control
By FIROZ SHAIKH
FATIMA SHAIKH

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
 What is the prevalence of overweight and
obesity in the United States? 65% & 31%

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

6. 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.

7. 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.

8. Causes of Obesity
 Overeating and Other Factors
 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

9. 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.

10. 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.

11. Causes of Obesity
 Genetics plays a role.
 How much variation
in weight gain among
individuals can be
accounted for by
genetic factors?
 Largest transmissible
variation is cultural.

12. Causes of Obesity
 A Mutant Gene?
 What is leptin?
 A satiety hormone that influences the
appetite control in the hypothalamus.
 A defective gene causes inadequate
leptin production.
 The brain receives an under assessment
of body’s adipose stores & urge to eat.

13. Causes of Obesity

14. Causes of Obesity
A defective ob gene
causes inadequate
leptin production.
Thus, the brain
receives an under
assessment of body’s
adipose stores and
urge to eat.
In addition to deficient
leptin production,
scientists also
propose the possibility
of defective receptor
action (via a leptin
receptor molecule on
brain cells), which
increases a person’s
resistance to satiety.

15. Causes of Obesity
 Physical Activity: an
important component
 See chart for children.
 For young & middle
aged men, physical
activity relates inversely
to body fat levels.
 No relationship between
caloric intake and body
fat levels.

16. 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 12% of
national health care.

17. Obesity
 How Much Fat is TOO Much?
 List three criteria for evaluating a person’s
level of fatness.
 % Body Fat
 Fat Patterning
 Fat Cell Size and Number

18. Percent Body Fat
 Overfatness
corresponds to any
body fat value 5%
above the average
value for age & sex.
 Borderline obesity in
young man > 20 & in
young woman >30%.
Standard Men Women
Lean < 5 < 8
Optimal 5-9 12-17
Good 10-20 18-25
Overfat 21-25 26-30
Obese >25 > 30

19. Fat Patterning
 Adipocytes from some
locations efficiently
capture excess
nutrients from the
blood-stream for
storage, while others
accumulate TGs but
readily release them
for use by other
tissues.

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

21. Fat Patterning
 Give an objective
standard for
establishing male- and
female-pattern
obesity.
 Male > .95 W:H ratio
 Female > .80 W:H

22. Fat Cell Number and Size
 Increases in adipose
tissue occurs in two
ways:
1. Fat cell hypertrophy
2. Fat cell hyperplasia

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

24. 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.

25. Weight Control
The Energy
Balance Equation
One pound of fat
contains 3,500
kcal

26. Dieting to Tip 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.

27. Dieting to Tip Energy Balance
 Resting Metabolic
Rate Lowered.
 Repeated cycles of
weight loss and
weight gain may
increase the body’s
efficiency to conserve
energy.
 Could lead to difficulty
losing weight.

28. Fat Cell Size and Number
 What happens to fat cell size and fat cell
number when adults lose weight?
 Fat cells shrink to a size smaller than adipocytes of
nonobese people, number remains sames.
 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

29. 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.

30. Dieting to Tip Energy Balance
Method Principle Disadvantage
Low CHO –
ketogenic
Increased ketone excretion
removes energy-containing
substances from body.
Ketogenic
High fat intake
contraindicated.
High
protein
Low caloric intake favors
negative energy balance.
Elevated thermic effect.
Expensive and
repetitious; difficult
to maintain.
Semi-
starvation
Decreased energy input
assures negative balance.
Requires close
supervision. LBM
High CHO,
low fat
Low carbohydrate favors
negative balance.
Initial water
retention.

31. 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

32. Diet Plus Exercise
 Combining exercise
and diet offers a
flexible yet effective
approach to weight
loss.
 Disadvantages of diet
alone include loss of
lean body tissue,
lethargy, possible
malnutrition, decrease
basal energy
expenditure.

33. Exercising to Tip the Balance
 Increased physical activity combined with
dietary restraint maintains weight loss
more effectively than long term diet alone.
 For previously sedentary, overweight
individual, moderate increase in physical
activity doesn’t necessarily increase intake.
 Recommend minimum of 3 days/week,
more frequently better. Minimum 300 kcal/
session.

34. Diet Plus Exercise
The Ideal Combination
 Exercise enhances fat
mobilization from
body’s 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.
 Risks from overweight
& obesity exceed those
from yo-yo dieting.

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 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.

38. Conclusions

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.