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Energy Balance, Body Composition

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Title: Energy Balance, Body Composition


1
Energy Balance, Body Composition Weight
Management
  • Readings Chapter 9

2
Energy Balance
  • unbalanced energy budgets can lead to weight gain
    or weight loss
  • excess energy beyond bodys needs increases fat
    storage
  • too little energy results in degradation of lean
    tissue to support energy needs
  • both extremes have serious health implications

3
Energy Balance
  • Maintaining weight means that

ENERGY IN
ENERGY OUT
4
Energy Intake
Figure 8-1, page 242
Energy In kilocalories from FOOD and DRINK How
do we determine how much energy food provides?
  • Bomb Calorimetry
  • food is burned in an insulated chamber surrounded
    by water
  • can measure
  • heat produced
  • O2 consumed

5
Energy Intake
  • Limitations of Bomb Calorimetry
  • more efficient than human body
  • Physiological Fuel Value the number of
    kilocalories the body derives from a food (less
    than bomb calorimetry)
  • Based on Food Composition
  • carbohydrates and protein provide 4 kcal/g, fat
    provides 9 kcal/g and alcohol 7 kcal/g

6
Regulation of Energy Intake
  • Recall from introductory Lecture
  • Hunger vs Appetite
  • the physiological drive for food that INITIATES
    food seeking behaviours
  • influenced by factors such as
  • Sensory
  • Cognitive
  • Environmental
  • Health
  • triggered by chemical messengers acting on the
    HYPOTHALAMUS
  • satiation

7
(No Transcript)
8
MORE SATIATING
boiled white potatoes baked fish oatmeal with
milk orange, apple whole grain pasta beefsteak,
baked beans popcorn, eggs rice white bread snack
chips, ice cream chocolate bar cake
doughnuts croissant
LESS SATIATING
9
Energy Expenditure
  • Thermogenesis
  • the generation of HEAT
  • used in physiology and nutrition studies as an
    index of how much energy the body is spending
  • Components of Energy Expenditure
  • basal/resting energy expenditure
  • energy of physical activity
  • thermic effect of food
  • adaptive thermogenesis

10
Thermic Effect of Food (5 10)
Physical Activity (25 35)
Basal/Resting Energy Expenditure (60 65)
11
Basal/Resting Energy Expenditure
  • the energy needed to maintain life when the body
    is at complete digestive, physical, and emotional
    rest
  • largest component of energy expenditure
  • measured as either basal metabolic rate (BMR) or
    resting energy expenditure (REE)

12
Estimating REE Harris-Benedict Equations
Male 66 (13.7 x weight) (5 x height) - 6.8 x age)
Female 655 (9.6 x weight) (1.8 x height) - (4.7 x age)
Example 20 year old male, weight 70 kg, height
175 cm 66 (13.7 x 70 kg) (5 x 175)
(6.8 x 20) 66 959 875 136 1,764 kcal/day
Table 8-3, page 249 How to, page 250
13
Factors that Influence BMR
  • increased lean body mass
  • growth and pregnancy
  • fever
  • thyroid hormone (thyroxin)
  • drugs such as caffeine, nicotine, amphetamines
  • height
  • stresses (e.g. diseases)
  • environmental temperature (both heat and cold)
  • increased age
  • increased body fat
  • sleep
  • malnutrition
  • starvation

Table 8-1, page 247
14
Energy of Physical Activity
  • voluntary movement of the skeletal muscle and
    support system
  • most VARIABLE component of energy expenditure
  • amount of energy required for an activity depends
    on
  • muscle mass
  • body weight
  • activity (intensity, duration, and frequency)

Table 8-2, page 248
15
Energy of Physical Activity
  • can also estimate based on an activity factor
    which is then multiplied by the BMR (or REE) to
    estimate average energy expenditure
  • Example
  • activity factor for moderately active men 45 -
    65 of BMR (REE)
  • BMR (REE) from previous example 1,764
  • therefore total energy expenditure is
  • 1,764 x 0.55 1,764 2734 kcal

energy of physical activity
BMR (REE)
Table 804, page 250
16
Physical Inactivity
  • favours a positive energy balance
  • changes in lifestyle over the last century
  • sedentary work
  • sedentary recreation

17
Thermic Effect of Food (TEF)
  • an estimation of the energy required to process
    food
  • includes energy needed to digest, absorb,
    transport, metabolize, and store food
  • proportional to the food energy consumed
  • estimated as 5 - 10 of energy intake
  • influenced by meal size, frequency and composition

18
Adaptive Thermogenesis
  • energy expended when an individual must adapt to
    change (e.g. stress, extreme cold, starvation,
    trauma)
  • extremely variable and highly specific
  • NOT included when calculating energy requirements

19
What determines a healthy weight?
Social perceptions?
Health Risks?
Hypertension
Diabetes
Arthritis
CVD
20
Body Mass Index (BMI)
underweight
normal
overweight
obese
lt 18.5
18.5 - 24.9
25 - 29.9
gt 30
21
Weakness of BMI?
  • does not account for body composition or body fat
    distribution
  • proportion of body weight that is FAT is more
    important for determining health risk
  • Kevin Bieksa, BMI 27.8

22
Body Composition
  • measurement of body fat
  • techniques to measure include
  • densitometry
  • underwater weighing
  • air displacement
  • DEXA
  • isotope dilution
  • skin fold thickness
  • bioelectrical impedance
  • CT scanning or MRI
  • near infrared interactance

23
Body Composition
  • Essential Fat
  • crucial for normal body functioning
  • Non-essential Fat
  • most accumulates in VISCERAL adipose tissue

24
Body Fat Distribution
  • Android (Central Obesity)
  • apple shape
  • more common in men and post-menopausal women
  • associated with increased health risks

25
Body Fat Distribution
  • Gynoid (Lower Body Obesity)
  • pear shape
  • more common in pre-menopausal women
  • pattern encouraged by estrogen progesterone

26
Waist Circumference
  • reliable predictor of fat distribution and
    abdominal fat
  • measured around abdomen, just above crest of the
    hip

27
Health Risks of Overweight
  • cardiovascular disease (CVD)
  • hypertension
  • Type II Diabetes
  • pulmonary disorders
  • sleep disorders (e.g. SLEEP APNEA)
  • gout
  • hypertension
  • various cancers
  • osteoarthritis
  • early mortality

28
Health Risks of Underweight
  • nutrient deficiencies
  • reproductive problems
  • cardiac arrhythmias
  • immunodeficiencies
  • rough, dry, scaly skin
  • poor temperature regulation
  • osteoporosis and increased risk of bone fractures
  • early mortality

29
Not the whole story
  • body weight is only one risk factor of many for
    chronic disease
  • for example, also need to consider
    cardiorespiratory fitness
  • normal weight unfit men have more than 2x risk of
    all-cause mortality than normal weight physically
    fit men
  • overweight fit men have LOWER mortality risk than
    normal-weight unfit men

30
Obesity
  • the second leading cause of preventable death
    after tobacco use
  • defined as an excessively high amount of body fat
    in relation to lean body mass
  • BMI gt 30
  • percent body fat gt 25 (men) or gt 32 (women)
  • waist circumference gt 40 (men) or gt 35 (women)

31
Causes of Obesity
  • Why do people consume more energy than they
    expend?
  • Explanations are many
  • genetic/physiological
  • environment
  • physical
  • cultural
  • socioeconomic
  • psychological

32
Genetics
  • Epidemiological Evidence
  • identical twins are 2x as likely to weigh the
    same compared to fraternal twins
  • if both parents are overweight a child is 2x as
    likely to be overweight compared to a child with
    only one overweight parent

33
Physiology of Weight Gain
  • an excess energy consumption beyond the needs of
    the body results in energy being stored
  • the amount of fat in a persons body reflects
  • the NUMBER of fat cells
  • the SIZE of fat cells
  • definitions hyperplastic and hypertrophic obesity

34
Fat Cell Development
  • number of fat cells increases most during late
    childhood and early puberty
  • fat cell size increases as cells fill with lipids
  • after a fat cell reaches its maximum size, it may
    divide again
  • with fat loss, the SIZE of the cells decreases,
    but not the NUMBER

35
Increase in fat cell size if energy intake
exceeds energy expenditure
With fat loss, the size of the fat cells shrinks,
but not the number
Increase in fat cell number during growth
Increase in fat cell number when fat cells reach
their maximum size
36
Lipoprotein Lipase (LPL)
  • enzyme on adipose and muscle cells that captures
    triglycerides from blood and promotes storage of
    fat
  • since obese individuals have more fat cells, they
    have higher levels of LPL than lean individuals
  • What does this mean for an obese individual who
    may only have a modest excess of energy intake?

37
Lipoprotein Lipase (LPL)
  • activity of LPL is regulated by estrogen in women
    and testosterone in men
  • lower body is less active in releasing fat from
    storage
  • weight loss increases LPL activity

Site of greatest LPL activity Effect on Body Fat Distribution
Women breasts, hips, thighs gynecoid shape
Men abdomen android shape
38
Leptin
  • peptide hormone coded for by the Ob gene
    expressed in adipose cells
  • stimulates hypothalamus to produce melanocortins
    that inhibit appetite and promote energy
    expenditure thus promoting weight loss
  • low levels result in increased production of
    Neuropeptide Y by the hypothalamus
    promoting weight gain
  • levels increase with increased body fat levels
    decrease with loss of body fat

39
Leptin
  • RARE genetic deficiency of leptin leads to
    obesity
  • leptin concentrations increase with weight gain
  • most obese individuals have high leptin levels
  • suggests that obesity is associated with leptin
    resistance
  • leptin also has many other functions

40
Neuropeptide Y
  • The actions of neuropeptide Y include
  • causes CARBOHYDRATE CRAVINGS
  • initiates eating
  • DECREASES ENERGY EXPENDITURE
  • INCREASES FAT STORAGE
  • These each favour a positive energy balance and
    promote weight gain.

41
Ghrelin
  • peptide hormone secreted by the stomach
  • acts on the hypothalamus to increase appetite by
    stimulating release of NPY

42
Fad Diets
43
Tell-tale Signs of a Fad Diet
  • promise dramatic weight loss
  • promote diets that are nutritionally unbalanced
  • promote extremely low energy intakes
  • dependant on food products and services
  • do not encourage permanent, realistic, lifestyle
    changes
  • cost
  • fail to inform clients about risks
  • promote unproven weight loss aids and miracle
    foods
  • rely on testimonials as evidence diet works
  • dont include exercise
  • have lists of good and bad foods

44
Why diets dont work
  • The body DEFENDS itself against weight loss!
  • Weight loss causes
  • increased LPL activity
  • decreased thyroid hormone production
  • decreased leptin

45
Why diets dont work
  • Other Factors
  • weight cycling
  • preoccupation with food, may lead to binge eating
  • often associated with irritability, depression,
    fatigue, poor concentration
  • does not resolve other issues such as low
    self-esteem, depression
  • may lead to social withdrawal
  • do not promote permanent healthy changes to
    lifestyle
  • unattainable weight loss goals can lead to
    frustration and failure

46
Weight Cycling
  • repeated dieting which produces rapid weight loss
    is often unsuccessful

Subsequent diet results in SLOWER weight loss
Regain
Diet
Weight
Regain
Weight Gain
Time
47
Low Carb Diets
  • Examples
  • Dr. Atkins New Diet Revolution, Carbohydrate
    Addicts, others
  • Premise
  • consume less than 20 50 g of carbohydrate per
    day
  • no limit on fat or protein intake
  • promise rapid weight loss
  • appealing because allowed to eat high fat tasty
    foods

48
Low Carb Diets
  • Successful in promoting weight loss through three
    primary mechanisms
  • low carbohydrate intake depletes glycogen stores
    leading to an initial rapid weight loss from
    water
  • low carbohydrate leads to production of
    ketones the state of ketosis
    inhibits appetite and decreases energy intake
  • diets tend to be low in total energy intake and
    all diets that reduce caloric intake result in
    weight loss

49
Low Carb Diets Health Risks
  • nutritionally inadequate
  • risk deficiencies of Vitamin E, A, folate,
    calcium, dietary fiber and others
  • high in total and saturated fat
  • increases risk of CVD
  • causes ketosis and associated metabolic risks
  • dehydration
  • increased urine production to excrete by-products
    of protein metabolism
  • increased risk of kidney disease

50
Treatment of Obesity
  • only 5 of individuals who successfully lose
    weight maintain their losses for at least a year
  • Healthy Weight Loss Goals and Strategies
  • make SMALL changes
  • set REALISTIC expectations (for amount of weight
    loss within a reasonable time frame)

51
Effective Weight Loss
  • Weight loss is most effective if it
  • is achieved GRADUALLY over time
  • embraces HEALTHY eating
  • incorporates PHYSICAL ACTIVITY
  • A reasonable weight loss rate for overweight
    individuals is
  • 0.5 2 lbs per week
  • 10 of body weight over six months

52
Establish REALISTIC Goals
  • what are goals based on?
  • societal standards or physical attractiveness?
  • improved health and reduced risk of chronic
    disease?
  • a modest weight loss can still have health
    benefits even if an individual remains overweight
  • unattainable weight loss goals can lead to
    frustration and failure

53
Develop a Healthy Eating Plan
  • severe energy restriction can have serious
    detrimental consequences
  • a minimum of 1200 kcal per day is required to
    maintain nutritional adequacy
  • reasonable suggestion 500 kcal deficit per day
  • equivalent to about 1 pound per week (1 lb body
    fat 3500 kcal)
  • achieve through combination of decreased energy
    intake and increased physical activity

54
Tips for Eating Plans
  • eat small portions and eat slowly
  • satiety signal indicating fullness is sent after
    a 20 minute lag
  • focus on complex carbohydrates
  • such as fresh fruits, vegetables, legumes, and
    whole grains
  • high fiber foods contribute more to satiation and
    satiety
  • limit high fat foods
  • high fat meals lower blood leptin levels

55
Tips for Eating Plans
  • limit empty calorie foods
  • includes high sugar and alcohol as well as fat
  • drink adequate water
  • need to meet water needs that were formerly
    provided by eating extra food
  • fills stomach between meals

56
Incorporate Physical Activity
  • individuals who combine BOTH diet and exercise in
    a weight loss program are more likely to
  • reduce body fat
  • retain more lean muscle mass
  • regain less weight

57
Incorporate Physical Activity
  • Regular activity has many benefits
  • 200 kcal expenditure
  • walking for 1 hour
  • cycling for 30 min
  • swimming for 20 min
  • running for 15 min
  • Lifestyle change - activity habits and daily
    routine
  • quick walks, stairs, fidgeting

58
Weight-Related Benefits of Exercise
  • short term increase in energy expenditure
  • long term increase in energy expenditure due to
    increased in lean tissue which increases BMR
  • improves body composition
  • helps with appetite control
  • decreases stress
  • improves self-esteem psychological well-being

59
Behaviour Modification Strategies
  • identify problem eating behaviours and develop
    alternate activities
  • e.g. replace snacking while watching TV with
    going for a walk, stretching exercises, etc
  • change the environment to reduce stimuli that
    encourage eating
  • e.g. keep fridge stocked with fruits and
    vegetables instead of cookies, chips and crackers
  • identify the reason why you eat
  • e.g. if stress, use exercise to relieve instead

60
Behaviour Modification Strategies
  • monitor your habits
  • e.g. what foods you eat, when ,where, and why you
    eat
  • develop supportive relationships with others or
    attend a support group
  • adopt permanent lifestyle changes to achieve and
    maintain a healthy weight

61
Weight Maintenance
  • expect a plateau within about 6 months
  • important to continue with healthy lifestyle
    changes, including exercise
  • formerly overweight and obese individuals need
    less energy to support needs than individuals who
    have never been overweight due to
  • increased efficiency at storing fat
  • lower BMR associated with weight loss

62
Weight Maintenance
  • Characteristics of Weight Loss Maintainers
  • lose weight slowly with small changes in eating
    and physical activity
  • consume regular meals
  • exercise regularly
  • make conscious efforts to avoid weight gain
  • change habits without depriving themselves of
    foods they enjoy
  • depend on social support
  • confront problems directly

63
Weight Maintenance
  • Characteristics of Weight Regainers
  • do not employ behaviour modification strategies
  • change diet radically to lose weight
  • do not include exercise as part of weight loss
    program
  • eat unconsciously in response to stress
  • take diet pills
  • lack social support
  • avoid problems rather than face them directly

64
Aggressive Obesity Treatment Drugs
  • There is NO effective drug to treat obesity that
    can be used over time without adverse side effect
    or the potential for abuse!
  • Sibutramine (Meridia)
  • inhibits uptake of neurochemical in the brain
    called serotonin
  • results in reduced appetite

65
Aggressive Obesity Treatment Drugs
  • Orlistat (Xenical)
  • inhibits activity of pancreatic lipase to block
    fat digestion and absorption by 30
  • taken with meals, most effective when combined
    with a reduced energy and low fat diet
  • Benzocaine
  • anesthetizes the tongue decreases taste
  • marketed under trade names of Slim Mints and Diet
    Ayds

66
Surgery
  • limit food intake by reducing the size of the
    stomach
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