Weight management

1
Weight management

• Overweight
• Obesity
• Underweight

2
Body Mass Index (BMI)

• Weight in Kg/square of height in meters

3
Distribution of body weights in US adults
4
Overweight and obesity

• 66 of of adults in US have BMI 25 or greater
• 33 children 2-19 in US are overweight or at risk
• So prevalent is considered an epidemic
• 300 million adults worldwide in both developed
  and developing countries

5
Fat cell development

• Fat cells increase rapidly in late childhood and
  early puberty
• Fat cells may continue to increase in number
  after body growth stops if there is an excess of
  calories
• Overweight people have more fat cells and the
  cells contain more fat that a lean persons

6
Fat cell loss

• Does not occur
• When weight loss occurs, fat cells shrink, but do
  not go away
• Makes it easier to regain weight

7
Lipoprotein lipase (LPL)

• Enzyme that promotes fat storage in fat cells and
  muscle
• Obese people have more activity in fat cells than
  lean people (same in muscle)
• Fat storage in obese people is more efficient and
  moderate increases in energy intake result in a
  more fat storage than a lean person

8
Acitivity of LPL

• Gender specific
• Partially regulated by estrogen and testosterone
• In women LPL is more active in breasts, hips and
  thighs
• In men LPL is more active in abdomen

9

• Release of lower body fat is less active in women
• Release of abdominal fat is less active in men
• Women have a harder time loosing weight,
  especially around hips and thighs

10
LPL activity after weight loss

• Weight loss signals fat cells to produce more LPL
• Greatest in people who were the heaviest before
  weight loss
• LPL works to restore set point

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Set point theory

• Body adjusts metabolism to restore original
  weight
• Energy expenditure increases after weight gain
  and decreases after weight loss
• Energy expenditures differ from what is expected
  from body composition alone
• Explains why it is difficult for an overweight
  person to maintain weight loss and for an
  underweight person to maintain weight gain

12
Causes of overweight and obesity

• Genetics
• Environment

13
Genetics

• True causative role is rare
• Prader-willi syndrome excessive appetite, short
  stature, massive obesity, mental retardation
• Does affect susceptibility to overweight and
  obesity
• Activity of leptin and grhelin is genetically
  regulated

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Leptin

• Obesity gene (ob) codes for leptin in adipose
  (fat) tissue and stomach cells
• Leptin is a hormone that affects the hypothalamus
  of the brain

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Leptin from fat cells

• Signals hypothalamus that fat stores are
  sufficient
• Signals long term satiety
• Promotes negative energy balance
• Suppresses appetite
• Increases metabolism

16
Leptin from stomach cells

• Released in presence of food
• Signals short term satiety

17
Defective ob gene

• In mice reduced amount of leptin and consequent
  weight gain
• Rare leptin deficiencies in human
• Leptin injections decrease appetite and stimulate
  weight loss

18
Normal ob gene

• Most obese people produce sufficient, or high,
  leptin
• Weight gain seems to increase concentrations
• Obese people may be resistant or insensitive to
  leptin
• Not a useful treatment for common overweight and
  obesity

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Leptin and energy intake decrease

• May be a starvation hormone
• Levels decline when energy intake is low
• Metabolism slows

20
Other functions of leptin

• Must be present for female fertility
• Stimulates growth of new blood vessels
• Promotes formation of red blood cells
• Supports immune system
• Elevated levels seen in obese children may
  promote early puberty

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Ghrelin

• Secreted by stomach
• Interacts with leptin
• Influences hypothalamus
• Promotes positive energy balance
• Stimulates appetite
• Promotes fat storage

22
Ghrelin levels

• Blood levels rise and fall before and after
  eating
• Fasting levels correlate inversely with body
  weight
• High in lean
• Exceptionally high in anorexics
• Indication that both body weight and nutritional
  status influence amounts
• Remain high after eating in Prader -Willi
  syndrome
• Remain higher than normal in obese people who
  binge eat

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Role of ghrelin during famine

• Maximizes fat storage
• Fights to maintain body weight

24
Factors affecting ghrelin levels

• Declines after gastric bypass surgery
• Declines in positive energy balanceweight gain
• Decline in proportion to PYY (polypeptide Y)

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PYY

• Secreted by GI tract cells in proportion to kcals
  consumed
• Signals satiety and decreases food intake
• May become a useful treatment in overweight and
  obesity

26
Other functions of ghrelin

• Growth
• Sleep
• Lack of sleep increases ghrelin and decreases
  leptin

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Uncoupled reactions

• Energy is lost as heat
• Energy is not trapped in ATP
• Occurs in brown fat
• Important in infants and hibernating animals
• Occurs in white fat and other tissues
• Resists weight gain
• Increases BMR
• Genetic variations occur
• May account, in part, for ease or resistance to
  weight gain

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Opposing hormones

• Satieting hormones
• Leptin
• PYY
• CCK
• Appetite stimulating hormone
• Ghrelin

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Ideal diet

• Stimulates satiety hormones and suppresses
  ghrelin
• Low fat, high fiber diets are the best at
  achieving this goal

30
Environment vs. genetics

• Both appear to play a role in body weight
• Interactions between the two occur
• Genetic factors involved in behaviors

31
Current trends

• Average weight has increased over the past three
  decades
• Genetics has not changed
• Recent weight gain trends appear to be
  environmentally caused

32
Overeating

• Encouraged by environment that constantly exposes
  us to high calorie, high fat foods that readily
  accessible
• Portion sizes of ready made food are often huge

33
Physical activity

• Current environment encourages inactivity
  through sedentary life styles
• Physical activity has been decreased through
  reliance on technology
• Home
• Work
• Transportation

34
Weight loss

• 35-45 women and 20-30 of men in U.S. are
  trying to loose weight

35
Weight loss and health status

• If overweight person is in good health, potential
  for harming health if weight loss is achieved
  through poor nutritional methods
• If overweight person is in bad health with two or
  more risk factors for chronic illness, weight
  loss through a nutritionally sound plan is
  advised
• If overweight person has a life threatening
  condition, weight loss through sensible means is
  indicated

36
Social issues

• Stereotyping overweight people
• Psychological problems resulting from hostility
  and contempt of others

37
Dangerous interventions

• Yo-yo dieting
• Fad diets
• Check out the end of the chapter for pros and
  cons
• Some weight loss products (non prescription)
• Ephedrine, which is no longer in use
• Laxatives found in dieters teas senna,
  cascara, aloe castor oil, etc.
• Gimmicks
• Cellulite same as any other fat

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Aggressive treatments drugs

• Prescription drugs
• Sibutramine
• Appetite suppressant
• Many side effects rise in blood pressure, rapid
  heart rate, dry mouth , headache
• Not indicated if patient has high blood pressure
• Orlistat
• Inhibits pancreatic lipase
• Blocks dietary fat by 30
• Side effects include gas, frequent bowel
  movement, reduced absorption of fat soluble
  vitamins
• OTC low dose version approved Alli

39
Aggressive treatment surgeries

• Gastric bypass
• Gastric band

40
Weight loss stategies

• Limit discretionary calories
• Limit fat
• Eat healthy fats
• Increase fiber
• Drink adequate water
• Eat lower energy dense foods
• Eat smaller portions
• Eat balanced diet
• Increase activity
• Continue behavior changes to maintain weight loss

41
Underweight

• Genetic and environmental causes

42
Weight gain strategies

• Increase caloric intake with energy dense foods
• Eat regular meals
• Large portions
• Extra snacks
• Drink extra juice and milk
• Strength training to add muscle, which weighs
  more than fat/equal volume

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The end