1. Energy Balance When a person maintains a healthy body weight: Energy In = Energy Out
Copyright 2005 Wadsworth Group, a division of Thomson Learning

2. ENERGY BALANCE Energy In - depends on the amount and
kind of food eaten
-Hunger-the physiological response to a
need for food triggered by chemical
signals from the hypothalamus
-Appetite-response to the sight, smell,
thought, or taste of food that triggers
eating
-Satiation-the feeling of fullness &
satisfaction during a meal
-Satiety-the feeling of fullness &
satisfaction after a meal

3. ENERGY EXPENDITURE Energy Out – depends primarily on 3 factors:
-Basal Metabolism
-Physical activity
-Thermic effect of food -the energy required to process food;
5-10% of energy needs

4. Components of Energy Expenditure
Copyright 2005 Wadsworth Group, a division of Thomson Learning

5. Components of Energy Expenditure
Basal metabolic rate (BMR): energy needed to maintain body processes at rest
For most adults, BMR = ~2/3 of daily energy output
Copyright 2005 Wadsworth Group, a division of Thomson Learning

6. Copyright 2005 Wadsworth Group, a division of Thomson Learning

7. Body Weight vs. Body Composition
Body weight = fat + lean tissue (including water)
Body composition – the proportions of muscle, bone, fat, and other tissue that make up a person’s total body weight
A higher percent body fat is associated with a lower BMR
Copyright 2005 Wadsworth Group, a division of Thomson Learning

8. Body Weight Distribution
Copyright 2005 Wadsworth Group, a division of Thomson Learning

9. Body Composition Methods used to assess body fat
1. Fatfold measures – thickness of fat
below skin measured using a caliper
at various sites (triceps, subscapular,
abdomen)
2. Hydrodensitometry - underwater
weighing; the “gold standard” for %
body fat, but not readily available

10. Body Composition 3. Bioelectrical impedance – uses a
low-intensity electrical current to
measure % body fat
4. Air displacement plethysmography
the amount of air displaced by the
body measured while sitting inside
a chamber
5. Dual Energy X-ray absorptiometry
(DEXA) - low dose X-rays that
differentiates fat-free soft tissue, fat
& bone

11. Body Composition Analysis of measures
1. Value of anthropometric measures
depends on:
a) Clinician’s skill
b) Equipment accuracy
c) Interpretation of values
2. Body composition can also be altered
by fluid retention, dehydration,
exercise

12. ENERGY EXPENDITURE Voluntary Activity – energy expenditure depends on:
1. Muscle mass
2. Body weight
3. Activity level – duration &
intensity

13. Copyright 2005 Wadsworth Group, a division of Thomson Learning

14. Copyright 2005 Wadsworth Group, a division of Thomson Learning

15. Estimating Energy Requirements
Formulas are available to estimate energy needs based on weight & level of physical activity
Gender-women generally have a lower energy requirements than men
Age-reduction in energy expenditure is about 5% per decade
Body size-a tall, thin person requires more energy than a short, wide person due to greater heat lose over larger surface area
Copyright 2005 Wadsworth Group, a division of Thomson Learning

16. Estimating Energy Requirements
Physical activity-level varies with level of intensity, gender and body size
Growth-pregnant woman and children have their own sets of energy equations
Copyright 2005 Wadsworth Group, a division of Thomson Learning

17. Estimating Energy Requirements
For men = x age + physical activity [(15.91 x wt) + (539.6 x ht)]
For women = 354 – physical activity
x [(9.36 x wt) + (726 x ht)]
Physical Activity Factor 1.0 – 1.48
Stress factor

18. Severe Stress
Acute conditions – major infections, trauma, surgery, burns
Characterized by increased need as
a result of increased BMR due to:
1. Rapid tissue breakdown
(negative nitrogen balance)
2. Heightened immune function
3. Repair of damaged tissues

19. Severe Stress Hypermetabolism peaks after 3-4
days; subsides by 7-10 days
Failure to meet protein/energy
needs -> organ failure
High stress often accompanied by
poor appetite & G.I. Problems
Drugs may further alter nutritional
status

20. Severe Stress
Chronic conditions – “wasting syndromes” that develop gradually & persist long-term as a result of disease
Energy – to spare protein & meet needs due to stress, fever, etc.

21. Wasting Syndromes
Congestive Heart Failure – reduced blood flow due to coronary heart disease, hypertension, obesity, severe stress
Nutritional consequences:
1. Increased energy needs due to
increased work load of heart &
lungs
2. Anorexia – cardiac cachexia
Chronic Obstructive Pulmonary Disease (COPD) – persistent obstruction of airflow due to emphysema & chronic bronchitis caused by smoking &/or environmental pollution
1. Increased energy needs for breathing

22. Wasting Syndromes
Cancer – uncontrolled growth of malignant cells/tumors
Nutritional consequences:
Cachexia – wasting assoc. with anorexia &
increased BMR
Contributing factors are:
1. Early satiety
2. Fatigue
3. Pain
4. Psychological stress
5. Cancer therapies Nutrient losses
7. Metabolic alterations

23. Wasting Syndromes Nutrition consequences:
HIV Infection (AIDS) – fatal disease of the immune system
Nutrition consequences:
Protein-energy malnutrition/wasting due to:
1. Anorexia related to psychological stress,
pain, lethargy & dementia, drug therapy,
cancer (Kaposi’s sarcoma)
2. Nutrient losses due to diarrhea and
malabsorption
3. Increased metabolism due to fever and
infections