Energy Balance, Body Composition

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Energy Balance, Body Composition Weight
Management

• Readings Chapter 9

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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

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Energy Balance

• Maintaining weight means that

ENERGY IN
ENERGY OUT
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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

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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

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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

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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
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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

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Thermic Effect of Food (5 10)
Physical Activity (25 35)
Basal/Resting Energy Expenditure (60 65)
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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)

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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
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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
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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
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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
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Physical Inactivity

• favours a positive energy balance
• changes in lifestyle over the last century
• sedentary work
• sedentary recreation

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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

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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

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What determines a healthy weight?
Social perceptions?
Health Risks?
Hypertension
Diabetes
Arthritis
CVD
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Body Mass Index (BMI)
underweight
normal
overweight
obese
lt 18.5
18.5 - 24.9
25 - 29.9
gt 30
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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

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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

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Body Composition

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

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Body Fat Distribution

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

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Body Fat Distribution

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

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Waist Circumference

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

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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

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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

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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

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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)

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Causes of Obesity

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

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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

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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

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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

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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
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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?

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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
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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

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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

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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.

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Ghrelin

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

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Fad Diets
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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

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Why diets dont work

• The body DEFENDS itself against weight loss!
• Weight loss causes
• increased LPL activity
• decreased thyroid hormone production
• decreased leptin

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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

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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
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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

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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

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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

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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)

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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Surgery

• limit food intake by reducing the size of the
  stomach