Transcript Slide 1

Energy Balance and
Body Composition
Chapter 8
ENERGY
IN
OUT
Energy Balance
 Excess energy is stored as fat
 Stored fat used for energy between meals
 Energy balance: energy in = energy out
 A shift in balance causes weight changes
 fat changes
 body composition changes- LBM, H2O
 1 pound of fat = 3500 kcalories
 Health fat storage 50,000 - 200,000 kcal
Energy In: Food Composition
 Direct measure of
food’s energy value
 Bomb calorimeter
 Indirect measure of
energy released
 Oxygen consumed
 Heat released
 kCalorie calculations
from grams prot,
CHO, fat, EtOH
Thermometer measures
temperature changes
Insulated
container
keeps
heat from
escaping
Motorized
stirrer
Reaction
chamber
(bomb)
Food is
burned
Heating
element
Water in which temperature
increase from burning food
is measured
Energy In: Kcal Intake
 Hunger: pain that causes food-seeking
 Appetite: integrated response to nerve
signals and chemical messengers
 Hypothalamus
 GI hormones, neuropeptide Y
 Satiation – fullness, stops eating
 Satiety – fullness that lasts til next meal
 Influences that override physiological signals
 positive (parties) and negative (grief)
1 Physiological influences
• Empty stomach
• Gastric contractions
• Absence of nutrients in small intestine
• GI hormones
• Endorphins (the brain’s pleasure
chemicals)
are triggered by the smell, sight, or taste
of
foods, enhancing the desire for them
5 Postabsorptive influences
1 Hunger
(after nutrients enter the blood)
• Nutrients in the blood signal the
brain (via nerves and hormones)
about their availability, use, and
storage
• As nutrients dwindle
satiety diminishes.
5 Satiety: Several
• Hunger develops
hours later
2 Sensory
influences
• Thought, sight,
smell, sound,
taste of food
2 Seek
food and
start meal
4 Satiation:
End meal
3 Keep
eating
4 Postingestive influences (after
food enters the digestive tract)
• Food in stomach triggers
stretch receptors
• Nutrients in small intestine
elicit hormones (for example,
fat elicits cholecystokinin,
which slows gastric emptying)
3
Cognitive
influences
• Presence of
others, social
stimulation
• Perception of
hunger,
awareness of
fullness
• Favorite foods,
foods with special
meanings
• Time of day
• Abundance of
Energy In: Kcal Intake
 Overriding hunger and satiety
 Stress eating and comfort foods
 External cues
 time of day
 availability
 sight, smell of food
 Environmental influences
 Example: buffet, large portion size
Energy In: Kcal Intake
 Sustaining satiation and satiety
 Nutrient composition
 Protein is most satiating
 Low-energy density / High-fiber foods also
more satiating
 High-fat foods – stimulate appetite
–low satiation
–strong satiety from SI (cholecystokinin)
837 kcal
71 g fat
55 kcal
3 g fat
For the same size portion, peanuts
deliver more than 15 times the
kcalories and 20 times the fat of
popcorn.
100 kcal
9 g fat
100 kcal
5 g fat
For the same number of kcalories, a
person can have a few high-fat
peanuts or almost 2 cups of high-fiber
popcorn. (This comparison used oilbased popcorn; using air-popped
popcorn would double the amount of
popcorn in this example.)
837 kcal
71 g fat
55 kcal
3 g fat
For the same size portion, peanuts deliver more than 15
times the kcalories and 20 times the fat of popcorn.
100 kcal
9 g fat
100 kcal
5 g fat
For the same number of kcalories, a person can have a few high-fat
peanuts or almost 2 cups of high-fiber popcorn. (This comparison
used oil-based popcorn; using air-popped popcorn would double
the amount of popcorn in this example.)
Energy In: Kcal Intake
 The Hypothalamus
 Control center for eating
 Integrates messages from brain, GI, liver
 Energy intake, expenditure, storage
 Gastrointestinal hormones- see list in margin
Energy Out: Kcal expended
 Thermogenesis- heat generated when kcal
broken down
 Total energy expenditure reflects 4
categories of thermogenesis
 Basal metabolism
 Physical activity
 Food consumption
 Adaptation
Components of Energy Expenditure
Basal Metabolism
 Uses about two-thirds of energy expended in
a day
 Metabolic activities
 All basic processes of life
 Basal metabolic rate (BMR)
 Variations for sleep and awake
 Weight
 Lean tissue
 Resting metabolic rate (RMR) not as precise
Components of Energy Expenditure –
Physical Activity
 Voluntary movement of skeletal muscles
 Most variable component of energy
expenditure
 Amount of energy needed depends on
 Muscle mass
 Body weight
 Activity
 Frequency, intensity, and duration
Components of Energy Expenditure –
Thermic Effect of Food
 Use kcal to digest/absorb kcal
 Acceleration of GI tract functioning in
response to food presence
 Requires energy, releases heat
 CHO: 5-10%, Fat: 0-5%, Protein: 20-30%
 Approximately 10 percent of energy intake
 High-protein foods > high-fat foods
 Regular meal > snacking
30-50%
Physical
activities
10%
Thermic effect
of food
50-65%
Basal metabolism
Components of Energy Expenditure
– Adaptive Thermogenesis
 Adapt to dramatic change in temperature,
trauma, exertion (extra work done by body)
 Amount expended is extremely variable
 Not included in energy requirement
calculations
Heat loss and
energy expenditure
relative to
surface area
Estimating Energy Requirements
 Gender
 BMR and LBM
 Growth
 Groups with
adjusted energy
requirements
 Age
 LBM, hormones,
activity level
 Physical activity
 PA Factor
 Body composition &
body size
 Height
 Weight
 Height / weight
 file:///E:/Media/Anim
ations/chapter8/08h
t1.html
Quick Calorie Ranges
•To gain weight: 35-45 kcal/kg
•To maintain weight: 25-35 kcal/kg
•To lose weight: 15-25 kcal/kg
Body Weight, Composition, Health
 Height/Weight indices unrelated to
body composition
 Both in use health for nutritional assessment
 Subjective “body image” dictates behaviors
 Ideal Body Weight (IBW)
 Body Mass Index (BMI)
 Useful for epidemiological studies
Body composition
is healthy
IBW / BMI says
he is overweight
Defining Healthy Body
Weight
Defining Healthy Body Weight
 Body mass index
 Relative weight for height
 BMI = weight (kg)
height (m)2
 Health-related classifications
 Healthy weight: BMI = 18.5 to 24.9
 Overweight: BMI = 25 to 29.9
 Obese: BMI = 30 to 39.9
 Morbidly Obese: BMI > 40
Table 1 Proposed range of ideal weights for women, ages 25 and over,
Height (with shoes) Weight in pounds (as ordinarily dressed)
Small frame
Medium frame
Large frame
5' 0" 105–13
5' 1" 107–15
5' 2" 110–18
5' 3" 113–21
5' 4" 116–25
5' 5" 119–28
5' 6" 123–32
5' 7" 126–36
5' 8" 129–39
5' 9" 133–43
5' 10" 136–47
5' 11" 139–50
6' 0" 141–53
112–20
114–22
117–25
120–28
124–32
127–35
130–40
134–44
137–47
141–51
145–55
148–58
151–63
119–29
121–31
124–35
127–38
131–42
133–45
138–50
142–54
145–58
149–62
152–66
155–69
160–74
Source: Metropolitan Life Insurance Company 1942
Centers for Disease Control
 BMI is a fairly reliable indicator of body fatness for most people.
BMI does not measure body fat directly, but research has shown
that BMI correlates to direct measures of body fat, such as
underwater weighing and dual energy x-ray absorptiometry
(DXA).1, 2 BMI can be considered an alternative for direct
measures of body fat. Additionally, BMI is an inexpensive and
easy-to-perform method of screening for weight categories that
may lead to health problems.
 BMI is used as a screening tool to identify possible weight
problems for adults. However, BMI is not a diagnostic tool. For
example, a person may have a high BMI. However, to determine if
excess weight is a health risk, a healthcare provider would need to
perform further assessments. These assessments might include
skinfold thickness measurements, evaluations of diet, physical
activity, family history, and other appropriate health screenings.
Centers for Disease Control
 Why does CDC use BMI to measure overweight
and obesity?
 Calculating BMI is one of the best methods for
population assessment of overweight and obesity.
Because calculation requires only height and weight, it
is inexpensive and easy to use for clinicians and for
the general public.
 BMI inches and pounds formula:
weight (lb) / [height (in)]2 x 703
Example: Weight = 150 lbs, Height = 5'5" (65")
Calculation: [150 ÷ (65)2] x 703 = 24.96
Assessing Your
Weight and Health Risk
 BMI calculator
file:///E:/Media/Animations/chapter8/08ht2.html
 Assessment of weight and health risk involves
using three key measures:
 Body mass index (BMI)
 Waist circumference
 Risk factors for diseases and conditions
associated with obesity
What 2 BMI ranges look like
 http://www.flickr.com/photos/77367764@N0
0/1462394033/in/set-72157602199008819/
 http://www.flickr.com/photos/77367764@N0
0/1458201494/in/set-72157602199008819/
Clinical Ht/Wt Measures
 IBW: Traditional ht/wt index
Women: 100 lbs + 5 lbs/in > 5 ft (5”4” = 120 lbs)
Men: 106 lbs + 6 lbs/in > 5 ft (6’2” = 190 lbs)
 UBW: Usual Body Weight- average weight
past 5-10 yrs. Useless reference point unless
person has been in good health
 ABW: Adjusted Body Weight- necessary for
setting kcal needs with OW/obese persons.
IBW + 1/3 excess wt = ABW
Excess Weight and Disease
Body Weights in U.S. Adults
Healthy weight
(BMI 18.5 – 24.9)
Overweight
(BMI 25 – 29.9)
Obesity
(BMI 30 – 39.9)
Underweight
(BMI < 18.5)
Extreme obesity
(BMI ≥ 40)
Body Fat and Its Distribution
 Important information for disease risk
 How much of weight is fat?
 Where is fat located?




Ideal amount of body fat depends on person
Normal wt man- 13-21%
Normal wt woman- 23-31%
Upper level for general disease risk
 Young men- 22%; Men over 40- 25%
 Young women- 32%; Women over 40- 35%
Body Fat and Its Distribution
Body Fat and Its Distribution
 Needing less body fat
 Some athletes: 5-10% men, 15-20% women
 Needing more body fat
 Cold climate, pregnancy
 Fat distribution affects health risk
 Visceral fat / central obesity / apple-shaped
 Subcutaneous fat / lower body fat /
pear-shaped
In healthy-weight people,
some fat is stored around the
organs of the abdomen.
In overweight people, excess
abdominal fat increases the
risks of diseases.
Upper-body fat is more common
in men than in women and is
closely associated with heart
disease, stroke, diabetes,
hypertension, and some types
of cancer.
Lower body fat is more
common in women than
in men and is not usually
associated with chronic
diseases.
Body Fat and Its Distribution
 Waist circumference
 Indicator of fat distribution & central obesity
 Indicator of high risk for diabetes and CVD
 Women: greater than 35 inches
 Men: greater than 40 inches
 Waist-to-hip ratio
 Other techniques for body composition
 More precise measures
Body Fat and Its Distribution
Skinfold measures estimate
body fat by using a caliper to
gauge the thickness of a fold
of skin on the back of the arm
(over the triceps), below the
shoulder blade (subscapular),
and in other places (including
lower-body sites) and then
comparing these
measurements with standards.
Hydrodensitometry measures
body density by weighing the
person first on land and then
again while submerged in
water. The difference between
the person’s actual weight and
underwater weight provides a
measure of the body’s volume.
A mathematical equation using
the two measurements
(volume and actual weight)
determines body density, from
which the percentage of body
fat can be estimated.
Bioelectrical impedance
measures body fat by using a
low-intensity electrical current.
Because electrolyte-containing
fluids, which readily conduct an
electrical current, are found
primarily in lean body tissues,
the leaner the person, the less
resistance to the current. The
measurement of electrical
resistance is then used in a
mathematical equation to
estimate the percentage of
body fat.
Air displacement
plethysmography estimates
body composition by having
a person sit inside a chamber
while computerized sensors
determine the amount of air
displaced by the person’s
body.
Dual energy X-ray
absorptiometry (DEXA) uses
two low-dose X-rays that
differentiate among fat-free
soft tissue (lean body mass),
fat tissue, and bone tissue,
providing a precise
measurement of total fat and
its distribution in all but
extremely obese subjects.
Health Risks Associated with
Body Weight & Body Fat
15
20
25
30
35
Body mass index
40
Risk increases
as BMI rises
Risk increases as
BMI declines
Mortality
Health Risks Associated with
Body Weight & Body Fat
 Body weight and fat distribution correlate
with disease risk and life expectancy
 Correlations are likelihoods, not causes
 Risks associated with being underweight
 Fighting against wasting diseases
 Menstrual irregularities and infertility
 Osteoporosis and bone fractures
Health Risks Associated
with Underweight
 1st question is WHY underweight?
 Smoking, substance abuse, body image
 Cancer, malnutrition, thyroid dz
 Risks associated with being underweight
 No reserves against wasting diseases
 Menstrual irregularities and infertility
 Osteoporosis and bone fractures
Health Risks Associated
with Overweight and Obesity
 Risks associated with being overweight
 Obesity is a designated disease
 Health risks include: DM, Htn, CVD, sleep
apnea, osteoarthritis, cancer, gallbladder dz,
kidney stones, resp. problems, CHF
 Likely to be disabled / immobile in later years
 Costs billions $$$
 300,000 obesity-related deaths/year
 Weight Gain > 20 lbs or 4 BMI units
Body mass index history and risk of type 2
diabetes: results from the European
Prospective Investigation into Cancer and
Nutrition (EPIC)-Potsdam Study.
 Am J Clin Nutr. 2006 Aug;84(2):427-33.
 Schienkiewitz A, Schulze MB, Hoffmann K, Kroke A, Boeing
H.
 Department of Epidemiology, German Institute of Human
Nutrition Potsdam-Rehbrücke, Germany.
[email protected]
 Severe weight gain defined as > 4 BMI units
Body mass index history and risk of type 2
diabetes: results from the European Prospective
Investigation into Cancer and Nutrition
(EPIC)-Potsdam Study.
 BACKGROUND: Obesity and increases in
body weight in adults are considered to be
among the most important risk factors for
type 2 diabetes.
 OBJECTIVE: The objective was to evaluate
and compare the associations between
weight changes during 2 different periods of
adult life and the risk of type 2 diabetes and
age at diagnosis.
Body mass index history and
risk of type 2 diabetes
 DESIGN: The study included 7720 men and
10,371 women from the European Prospective
Investigation into Cancer and Nutrition (EPIC)Potsdam Study with information on weight
history; 390 men and 303 women of these
participants received a clinical diagnosis of type
2 diabetes during 7 y of follow-up. Multivariate
Cox regression models were used to estimate
the relative risk (RR) of weight changes between
ages 25 and 40 y and ages 40 and 55 y.
Body mass index history and
risk of type 2 diabetes
 RESULTS: RR estimates in men and women were
slightly higher for each unit of BMI gain between ages
25 and 40 y [men: 1.25 (95% CI: 1.21, 1.30); women:
1.24 (1.20, 1.27)] than between ages 40 and 55 y
[men: 1.13 (1.10, 1.16); women: 1.11 (1.08, 1.14)].
Severe weight gain between ages 25 and 40 y was
associated with a higher diabetes risk in men (1.5
times) and in women (4.3 times) than were stable
weight in early adulthood and weight gain in later life,
and it resulted in an average lower age at diabetes
diagnosis in men (5 y) and in women (3 y).
Body mass index history and
risk of type 2 diabetes
 CONCLUSION: Weight gain in early
adulthood is related to a higher risk and
earlier onset of type 2 diabetes than is
weight gain between 40 and 55 y of age.
Health Risks Associated with
Excess Body Weight & Body Fat
 Cardiovascular disease
 High LDL, Low HDL, Htn, DM
 Metabolic Syndrome & Inflammation
 Htn, High WC, TG, ser. Glucose; low HDL
 Diabetes – type II
 Central obesity
 Weight gains and body weight
 Cancer
 Especially hormone-mediated
Health Risks Associated with
Body Weight & Body Fat
 Inflammation & metabolic syndrome
 Change in body’s metabolism
 Cluster of symptoms
 Fat accumulation
 Inflammation
 Elevated blood lipids
 Promote inflammation
Double
Whammy
Highlight 8
Eating Disorders
Eating Disorders
 Three disorders
 Anorexia nervosa
 Bulimia nervosa
 Binge eating disorder
 Prevalence of various eating disorders
 Causes
 Multiple factors
 Athletes and eating disorders
Female Athlete Triad
 Disordered eating
 Unsuitable weight standards
 Body composition differences
 Risk factors for eating disorders in athletes
 Amenorrhea
 Characteristics
 Osteoporosis
 Stress fractures
Female Athlete Triad
Other Dangerous Practices of
Athletes
 Muscle dysmorphia
 Characteristic behaviors
 Similarities to others with distorted body
images
 Food deprivation and dehydration practices
 Impair physical performance
 Reduce muscle strength
 Decrease anaerobic power
 Reduce endurance capacity
Anorexia Nervosa
 Distorted body image
 Central to diagnosis
 Cannot be self-diagnosed
 Malnutrition
 Impacts brain function and judgment
 Causes lethargy, confusion, and delirium
 Denial
 Levels are high among anorexics
Anorexia Nervosa
 Need for self-control
 Protein-energy malnutrition (PEM)
 Similar to marasmus
 Impact on body
 Growth ceases and normal development
falters
 Changes in heart size and strength
 Other bodily consequences
Anorexia Nervosa
 Treatment
 Multidisciplinary approach
 Food and weight issues
 Relationship issues
 After recovery
 Energy intakes and eating behaviors may
not return to normal
 High mortality rate among psychiatric
disorders
Anorexia Nervosa
Bulimia Nervosa
 Distinct and more prevalent than anorexia
nervosa
 True incidence is difficult to establish
 Secretive nature
 Not as physically apparent
 Common background characteristics of
bulimics
Bulimia Nervosa
 Binge-purge cycle
 Lack of control
 Consume food for emotional comfort
 Cannot stop
 Done in secret
 Purge
 Cathartic
 Emetic
 Shame and guilt
Bulimia Nervosa
Negative
self-perceptions
Restrictive
dieting
Purging
Binge
eating
Stepped Art
Fig. H8-2, p. 266
Bulimia Nervosa
 Physical consequences of binge-purge
cycle
 Subclinical malnutrition
 Effects
 Physical effects
 Tooth erosion, red eyes, calloused hands
 Clinical depression and substance abuse
rates are high
Bulimia Nervosa
 Treatment
 Discontinuing purging and restrictive diet
habits
 Learn to eat three meals a day
 Plus snacks
 Treatment team
 Length of recovery
 Overlap between anorexia nervosa and
bulimia nervosa
Bulimia Nervosa
Binge-Eating Disorder
 Periodic binging
 Typically no purging
 Contrast with bulimia nervosa
 Compare with bulimia nervosa
 Feelings
 Differences between obese binge eaters
and obese people who do not binge
 Behavioral disorder responsive to treatment
Eating Disorders in Society
 Society plays central role in eating disorders
 Known only in developed nations
 More prevalent as wealth increases
 Food becomes plentiful
 Body dissatisfaction
 Characteristics of disordered eating