Weight Management

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Weight Management

• What factors interact to determine body weight?

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Gaining Losing weight

• Whether a person gains or loses weight depends
  on
  
• Energy intake vs. energy expenditure
• Genetic factors
• Childhood weight
• Behavioral factors
• Social factors

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Energy Balance

• Energy balance
• Occurs when energy intake energy expenditure
• Energy intake kcal from food
• Energy expenditure energy expended at rest
  during physical activity

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Influences on weight

• Physiological
• Developmental
• Genetic
• Environmental
• Psychological
• Environment (social, cultural, etc.)

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Fat Cell Development
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Genetic factors

• Different hypotheses explain the impact of
  genetics on body fat
  
• Thrifty Gene Theory
• Set-point Theory
• Leptin Theory

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Thrifty Gene Theory

• H1 individuals with the gene use less energy (at
  all times) than people who do not possess the
  gene
  
• More efficient fat storage
• Lower metabolic rates
• Evolutionary story Protection against starvation
  during lean times
  
• Applied to American Indian populations with high
  rates of obesity diabetes
  
• Evidence No direct little indirect

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Fat Cell Metabolism

• Lipoprotein Lipase (LPL) binds to cells and
  stimulates them to accept triglycerides from
  Lipoproteins
  
• Results in efficient fat storage
• Men have high levels in abdomen
• Women have high levels in hips thighs
• Enzymes that burn fat for energy have differing
  concentration in different people
  
• May contribute to body maintaining a particular
  weight

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Set-Point Theory

• H1 Body is tuned to maintain weight within a
  narrow range, or set-point
  
• Body appears to maintain weight _at_ present level
• Explains rebound weight gain (dieters) why
  over-eating often does not result in weight gain
  
• Can change set point by maintaining long term
  changes in diet exercise

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Leptin Theory

• Leptin hormone produced by adipose cells
  signals hypothalamus
  
• Binds to neurons in satiety center in
  hypothalamus inhibits neurons that stimulate
  feelings of hunger
  
• Increased production of leptin reduces food
  intake, body weight and body fat
  
• Virtually ALL obese people have leptin that works
  finebut maybe theres a problem in the detection
  of leptin
  

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Leptin Pathway
Could be a breakdown at many different points
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Mice with and without Leptin
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Ghrelin

• Produced by stomach cells
• Interacts with leptin at hypothalamus
• Increased levels in blood stimulate appetite and
  efficient energy storage
  
• Levels are high in lean people, lower in obese
• Levels rise and fall in lean people, but do not
  decline in obese
  
• Increased by lack of sleep
• Probably used (by body) to maintain weight

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Ghrelin Leptin
Appear to work together to maintain homeostasis
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Uncoupling proteins

• Brown Adipose tissue
• Prevents cells from using freed energy to make ATP

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Childhood weight

• Environmental factors in childhood influence
• Food choices
• Activity levels
• Later adult behaviors
• Childhood overweight increases the risk of heart
  disease and premature death as an adult

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Behavioral Choices

• Food Choices
• Overeating dietary fat increases obesity faster
  than overeating carbs or proteins
  
• Less energy required to digest fats than other
  two
  
• Little digestion is required
• Virtually no energy expended in absorption
• More easily stored as adipose tissue
• No conversion necessary

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Behavioral Choices

• Hunger vs. Appetite
• Appetite psychological desire to eat leads to
  overeating
  
• Satiety mechanism malfunction
• Increase satiety
• Stomach expansion (baroreceptors)
• Nutrient absorption
• Increase blood glucose levels
• Hormones leptin, serotonin, CCK
• Decrease satiety
• Hormones Beta-endorphins
• Neuropeptide Y increases proportion of energy
  stored as fat
  
• Decreased blood glucose levels

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Social Environmental Factors

• Social factors influencing our diet
• Family or cultural traditions
• Holidays and celebrations
• Easy access to high-fat foods
• Less physically active lifestyles
• Societal expectations of the perfect body

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How many kcals do we need?

• Manual calculation
• BMR (women) body weight (kg) 0.9 kcal/
  kg/hour
  
• BMR (men) body weight (kg) 1.0 kcal/ kg/hour
• 77.3 kg 1 24 1855 kcal
• Activity some percentage of BMR Ex 70
• 1855 kcal 0.70 1299 kcal
• 1855 1299 3154 kcal
• How many are you eating? Recall
• Fats 9 kcal/gram
• Carbs 4 kcal /gram
• Proteins 4 kcal/gram

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A healthful body weight is

• Appropriate for your age
• Maintained without constant dieting
• Acceptable to you
• Based on family history of body shape and weight
• Promotes healthful eating habits and allows for
  regular physical activity

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Evaluating body weight

• Body Mass Index BMI
• BMI weight (kg) / height (m)2
• Weight (lbs)/2.2 weight (kg)
• Height (in)2/39.37 height (m)2
• My BMI 75kg/(1.85 m)2
• My BMI 75kg/3.4225m
• My BMI 21.91

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Achieving maintaining healthy weight

• Healthful weight change requires
• Gradual change in energy intake
• Regular and appropriate physical exercise
• Application of behavior modification techniques

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Diet shifts

• Realistic energy intake goals
• Reduce it by a manageable amount. More likely to
  maintain it and stay away from unhealthful
  energy
  
• Eat recommended serving sizes
• Reduce intake of high-fat foods
• Go for fiber density
• Reduce intake of high-energy foods
• Go for nutrient density
• Avoid empty calories

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Activity shifts

• Increases energy expenditure
• Increases BMR
• Short-term remains elevated for a couple hours
  after exercise
  
• Long-term added lean muscle mass requires more
  energy to sustain
  
• Reduces appetite
• After moderate-intense exercise, body is
  unprepared for digestion absorption
  
• Reduces stress may boost self-esteem