1. Energy Balance and Body Composition Lancelot McLean, PhD. lmclean@llu
Energy Balance and Body Composition Lancelot McLean, PhD.

2. 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
1 pound of fat = 3500 kcalories
For each 3500 kcalories eaten in excess, 1lb fat gain
Body fat is about 87% fat, some protein and water

3. Defining Healthy Body Weight
How much should a person weigh?
Body Mass Index (BMI)
BMI = weight (kg)
height (m)2
Healthy weight: BMI = 18.5 to 24.9
Not a measure of body composition
A muscular athlete may be classified as overweight by BMI standards and not be “overfat”.
Arnold Schwarzenegger won Mr. Olympia with BMI of 31

5. Defining Healthy Body Weight

6. Body Fat and Its Distribution
Two important information for disease risk missing from weight only
How much of weight is fat?
Where is fat located?

7. Body Fat and Its Distribution
How much of body weight should be FAT?
General disease risk levels
Young men: 22%; Men over 40: 25%
Young women: 32%; Women over 40: 35%

8. Body Fat and Its Distribution
Fat distribution
Visceral fat
Stored around the organs of the abdomen
Upper body fat / Central Obesity
Associated with increased risk of heart disease, stroke, diabetes, hypertension, and some types of cancer
Most common in men and to a lesser extent postmenopausal women
Subcutaneous fat
Stored around hips and thighs
Lower body fat
Mostly common in women during reproductive years
Seems relatively harmless

9. Body Fat and Its Distribution

10. Body Fat and Its Distribution

11. Body Fat and Its Distribution
Waist circumference
Good indicator of fat distribution & central obesity
Women: greater than 35 inches
Men: greater than 40 inches
High risk of diabetes and cardiovascular disease
Waist-to-hip ratio
Used by some researchers
Does not provide additional information

12. Health Risks Associated with Body Weight & Body Fat

13. Health Risks Associated with Body Weight & Body Fat
Cardiovascular disease
Elevated blood cholesterol & hypertension
Diabetes – type II
Central obesity
Central body fat cells appear to be larger and more insulin resistant than lower body fat cells
Cancer
Relationship is not fully understood

14. Overweight and Obesity
Major health problem in the U.S.
66% of US adults overweight or obese
Growing concern worldwide
Prevalence continues to increase
Women, Poor, African Americans, and Hispanics
Children
33% of US children and adolescents ages 2-19 years overweight or obese
BMI of 25 or greater
Epidemic is worldwide
Not merely among industrialized countries
> 300 million adults, 155 million children worldwide

15. Overweight and Obesity

16. Fat Cell Development Occurs when energy in exceeds energy out
Stored in fat cells of adipose tissue
Fat size and number
Obese individuals have larger and more fat cells than healthy weight individuals
Expand as they accumulate more triglycerides then proliferate more
Energy out exceeds energy in
Fat cell size decreases; no change in number
People with extra fat cells can regain lost weight rapidly
Prevention of obesity is critical during growing years when fat cells proliferate
Ongoing research on how to induce fat cell death to decrease number

17. Caloric restriction slows aging and extends life of several species, including some mammals

18. Fat Cell Development

19. Fat Cell Metabolism Lipoprotein lipase (LPL) activity
Removes triglycerides from blood for storage in adipose tissue and muscle cells
Obese people have more LPL activity in adipose tissue than lean people
Making fat storage efficient
Activity differs in varying body regions
Women
Breast, hips, thighs
Men
Abdomen

20. Fat Cell Metabolism Rate of fat breakdown slower in women than men
After weight loss lipoprotein lipase (LPL) activity increase
Making regain of weight relatively easy
After weight loss fat oxidation is not as efficient
Body tries to restore the weight you previously had

21. Causes of Overweight & Obesity
Genetics
Genetics may determine predisposition to obesity
Adopted children more similar in weight to biological parents
Identical twins twice as likely to weigh the same
However lifestyle can alter the outcome
Proper diet and exercise
Researchers have identified an obesity gene, called ob
Expressed primarily in the adipose tissue
Codes for the protein LEPTIN

22. Causes of Overweight & Obesity
LEPTIN
Acts as a hormone
Leptin from adipose tissue promotes negative energy balance
Suppressing appetite
Increasing energy expenditure
Leptin from stomach is released in response to food presence

23. Causes of Overweight & Obesity Mice with and without Leptin
With Leptin
Without Leptin

24. Causes of Overweight & Obesity
Leptin deficiency
Genetic deficiency of leptin or genetic mutation of its receptor
Rare
But has been identified in human beings
Constantly hungry and eat considerable more than peers
With daily leptin injections they lose a substantial amount of weight
However vey few obese people have a leptin deficiency
In fact leptin levels rise with increasing BMI to try and diminish appetite, but to no avail
Due to “leptin resistance”

25. Causes of Overweight & Obesity
Adiponectin
Lean people have higher amounts
Inhibits inflammation and protects against insulin resistance and cardiovascular disease
Researchers trying to find ways to raise adiponectin levels in obese individuals so as to decrease disease risks

26. Eating Disorders Anorexia nervosa Bulimia nervosa
Eating disorder characterized by refusal to maintain a normal body weight
Intense fear of gaining weight or becoming obese
Disturbance of body image resulting in a feeling of being fat or having fat in certain areas even when extremely emaciated
Bulimia nervosa
Eating disorder involving episodic binge eating followed by behaviors designed to prevent weight gain, including purging, fasting and excessive exercise
Binge eating disorder
Eating disorder characterized by binge eating, rarely purging and exert less restraint than bulimics during times of dieting