1. Energy Balance and Weight Management
Chapter 7

2. Overweight and Obesity
Major health problem in the U.S.
Growing concern worldwide
Prevalence increasing among all socioeconomic groups
2/3 of adults
Children: 1/3, ages 2-19
Overweight: BMI of 25-29
Obese: BMI of 30 or greater
Epidemic is worldwide
Not merely among industrialized countries

5. This Took 20 Years!

6. What’s Going On? Increased Intake Decreased Energy Expenditure
Portion Distortion
Appetite versus Hunger
Decreased Energy Expenditure
Changes in recreational activities
Modern technology

7. Weight Management Terms
Energy balance occurs when energy consumed equals energy expenditure.
Energy is measured in kilocalories (kcal, kcalories) or kilojoules (kjoules, kJ).
A kcalorie is a measure of the amount of energy that is supplied to or expended by the body.
Body Mass Index (BMI) is a mathematical comparison of weight to height
Overweight is being too heavy for one’s height or having a BMI of 25–29.
Obesity is characterized by excess body fat or a BMI over 30.

8. Energy In: Food Composition
Direct measure of food’s energy value
Bomb calorimeter
kCalorie calculations
Not an exact science when it comes to how food behaves the body!

9. Energy Balance Excess energy is stored as fat
Fat is used for energy between meals
Energy balance: energy in = energy out
A shift in balance causes weight changes
Not simply fat changes
When weight loss occurs, body energy stores are used
When weight gain occurs, body energy stores are built

10. Energy Balance: Ins vs. Outs

11. Using Nutrients for Energy (ATP)

12. Storing Energy in Adipose Tissue

13. Fat Cell Development Energy in exceeds energy out Body fat
Stored in fat cells of adipose tissue
Body fat
Number and size of fat cells
Periods in life when fat cell numbers increase: puberty and excess intake
Cell proliferation
Energy out exceeds energy in
Fat cell size decreases; no change in number

14. During growth, fat cells increase in number.
When energy intake exceeds expenditure, fat cells increase in size.
When fat cells have enlarged and energy intake continues
to exceed energy expenditure, fat cells increase in number
again.
With fat loss, the size of the fat cells shrinks but not the number.
Figure 9.2: Fat Cell Development.
Fat cells are capable of increasing their size by 20-fold and their number by several thousandfold.

15. Estimating Energy Requirements
Gender
BMR
Growth
Groups with adjusted energy requirements
Infants, children, adolescents, pregnant and lactating women
Age
Tends to decrease with time
Physical activity
Kcal burned in moment vs. afterburn
Body composition & body size
Height
Weight

16. Estimated Energy Requirement

17. Physical Activity Factor (PA)

18. Estimating PA Intensity

19. Calculating Body Mass Index
Body mass index (BMI)
Relative weight for height
BMI = weight (kg)
height (m)2
Health-related classifications
Underweight: <18.5
Healthy weight: 18.5 to 24.9
Overweight:
Obese: 30 or above
Not a measure of body composition!

20. Assessing Body Composition
Bioelectric impedance analysis
Skinfold thickness
Underwater weighing
Dilution methods
Radiologic methods

21. Measurement of Body Composition

22. Excess Body Fat and Disease Risk

23. 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 individual
Healthy ranges
Men: 13-21%
Women: 23-31%
Obese individuals: up to 70% body fat

24. Body Fat and Its Distribution
Weight alone doesn’t tell the whole story!
Waist circumference
Indicator of fat distribution & central obesity
Women: risk at greater than 35 inches
Men: risk at greater than 40 inches
Waist-to-hip ratio:
Women: risk at greater than 0.8
Men: risk at greater than 0.9

25. Fat Distribution: Visceral Fat

26. Apple- vs. Pear-Shaped Bodies

27. Health Risks Associated with Body Weight & Body Fat
Risks associated with being overweight
Obesity is a designated disease
Health risks
Heart disease, hypertension, diabetes, sleep apnea, osteoarthritis, some cancers, gallbladder disease, kidney stones, infertility, complications in pregnancy and surgery
More likely to be disabled in later years
Costs
Money: health care costs as much or more than that of smoking
Lives: ~300,000/year from related diseases

28. Estimating Disease Risk

29. Who would benefit from weight loss?

30. Defining Healthy Body Weight
What is ideal?
Not appearance-based
Perceived body image and actual body size can be quite different
Dissonance can lead to damaging behaviors
Subjectivity of ideal body type
Shifts from one culture to another, from one decade to the next
Little in common with health

31. Body Fat and Its Distribution

32. Health Risks Associated with Body Weight & Body Fat
Body weight and fat distribution correlate with disease risk and life expectancy
Correlations are not causes
Overweight does not equal unhealthy
Risks associated with being underweight
Fighting against wasting diseases
Menstrual irregularities and infertility
Osteoporosis and bone fractures

33. Health Risks Associated with Body Weight & Body Fat