1. Chapter 7 Body composition basics

2. COMING UP IN THIS CHAPTER
Understand the basic composition of your body
Identify factors that influence your body composition
Examine the relationship between body composition and health
Assess your body composition
Identify strategies for making changes in your body composition

3. Basics of Body Composition
What is body composition?
Body composition: the makeup of the body
The relative proportions of different types of body tissues
Muscle
Bone
Fat
Other vital tissues
Percent body fat is the measure most often used to define and evaluate body composition

4. Basics of Body Composition
Is there such a thing as good body fat?
The body needs fat in order to function
Essential fat
Found in the central nervous system, bone marrow, various organs
Surrounds nerve fibers in the brain allowing for the transmission of messages
Key component of cell membranes
Important in healthy hormone production
8–12 % in females and 3–5 % in males
More…

5. Basics of Body Composition
Storage fat (adipose tissue)
Site for storage of energy
Also releases molecules and hormones that that affect appetite, blood pressure, immune system function, insulin and glucose levels
Too much has negative health effects
Visceral fat
Found deep within the abdominal cavity
Surrounds internal organs
Subcutaneous fat
Found just beneath the skin
Insulates the body and regulates temperature

6. Basics of Body Composition
My friends and I look about the same, but most of them weigh around 15 pounds less than I do. How is that possible?
Differences in tissue density
Differences between muscle and fat
Differences in body composition

7. Figure 7-1 Body composition of young adults (ages 20–24)

8. Figure 7-2 Visceral and subcutaneous fat in the abdomen

9. Basics of Body Composition
What is metabolism?
Metabolism: all the processes that require energy (calories from foods) and maintain body functioning
Energy balance: connection between metabolism and body composition

10. Basics of Body Composition
The amount of energy your body requires depends on three criteria:
Resting metabolic rate (RMR)
Energy required to maintain essential processes at rest
Depends on genetics, body size, and body composition
Muscle is more metabolically active than fat
Resistance training increases RMR
Dietary thermogenesis
The energy required to digest and process food
Physical activity
Energy expended in daily living as well as formal exercise

11. Basics of Body Composition
How do we get fat, literally? What causes the body to retain fat, and where does it go?
The body produces and stores fat when more energy is consumed than is used to maintain body functions and fuel activities
Protects from starvation
3,500 calories is the equivalent of a pound of body weight
More…

12. Basics of Body Composition
Most fat is stored in fat deposits, which are about 80 percent fat and 20 percent support cells, immune cells, and blood vessels
If you gain weight as fat, these fat cells enlarge, storing more fat
If you lose body fat, your fat cells shrink

13. Basics of Body Composition
Do overweight and obese mean the same thing?
Obesity is considered more extreme and serious
Overweight: weight above a recommended range, based on large-scale population surveys or studies
Obesity: higher degree of overweight, characterized by excessive body fat
Height and waist circumference are also considered in evaluating health risks

14. Basics of Body Composition
Have Americans gotten fatter?
On average, the American population has become heavier
The average weight for adults in their twenties is 15 pounds heavier today than 20 years ago
The prevalence of obesity has increased significantly

15. Figure 7-3 Trends in overweight and obesity among U. S
Figure 7-3 Trends in overweight and obesity among U.S. adults, 1962–2010

16. Factors Affecting Body Composition
Do shorter people have a higher body-fat percentage?
Body composition is based on a combination of factors
Height is related, but doesn’t predict the amount of body fat within your body
Height is a body composition factor not in your control
Some of the other factors, you can control

17. Genetics
Is my body composition going to be similar to that of my parents? Is body composition based on genetics at all?
The contribution of heredity will be between 25 and 75 percent
Hundreds of genes affect body fat
INSIG2 and FTO genes
Influence body size; amount and distribution of body fat; and response to exercise
Body composition is also influenced by numerous environmental factors

18. Genetics Why is it so hard for skinny guys to gain muscle mass?
High resting metabolic rate
Bodies that aren’t designed for muscle gain
Can build muscle, but won’t be able to radically change body type

19. Biological Sex
I know men and women’s bodies are different, but when my boyfriend and I eat together, it seems as if I am more susceptible to weight gain than he is. Why?
Body composition differs between the sexes and varies with age
Birth weights
Young years
Adolescence and puberty
Mid-life

20. Figure 7-4 Average percent of body fat by age and sex

21. Biological Sex
Why do men gain fat in their belly, and women in their hips?
Men are more likely to store excess fat in the abdomen; women, in hips and thighs
Android: apple-shaped; more common in men and postmenopausal women
Gynoid: pear-shaped; more common in premenopausal women

22. Figure 7-5 Body-fat distribution

23. Age Does body composition always get worse as we get older?
It is hard to separate the effects of age from use
Less physical activity and exercise:
With each decade they don’t strength train, adults lose about 4–6 pounds of muscle mass, and their resting metabolic rate also declines
Physical activity and exercise, especially resistance training, can maintain muscle mass through the aging process

24. Ethnicity Do different ethnic groups have different body compositions?
Body composition patterns related to sex and age are consistent across all ethnic groups
However, ethnic differences have been found in average height, weight, and body composition
Differences related to culture and ethnicity

25. Table 7-1 Comparison of Average Height, Weight, Body Mass Index, and Total Abdominal Fat Among Adults from Four Ethnic Groups

26. Lifestyle and Environment
Some of my cousins are really fat, but my brothers and I are skinny. Why aren’t we more alike since we have many of the same genes?
Genetics, age, and sex are factors in body composition, but different lifestyles and environments also play a role
More…

27. Lifestyle and Environment
Energy intake: if you consume more calories than you burn, you will gain weight
Physical activity: daily activity and exercise affect energy balance and body composition
Sleep: insufficient sleep is associated with increased body fat; may interfere with the ability to regulate appetite; and increases the risk of diabetes
Stress: psychological stress linked to increased energy intake, weight gain, and excess abdominal fat; along with insulin resistance

28. Body Composition and Wellness
Why is it important to know how much fat is in your body? What can one statistic like percent body fat tell you about health?
Body composition is one component of health-related fitness
Maintaining an appropriate level of body fat is vital to a healthy, longer life

29. Problems Associated with Excess Body Fat
My dad is really big (I don’t like to say “fat”) and I worry about him. What are his greatest health risks?
Cardiovascular disease
High blood pressure and fat in the blood
Type 2 diabetes
There is a direct relationship between excess body fat and type 2 diabetes
Cancer
Breast, prostate, colon, pancreas, esophagus, endometrium, and kidney

30. Problems Associated with Excess Body Fat
Other problems associated with excess body fat:
Joint problems
Osteoarthritis
Sleep apnea
Asthma
Gall bladder and liver diseases
Reproductive problems
Shortened life expectancy

31. Problems Associated with Excess Body Fat
Can you be sort of overweight or overfat and healthy at the same time?
The consequences of excess body fat and weight are controversial and the subject of ongoing research
Certain factors can make a difference
Age and weight history
An overweight youngster will be exposed to the effects of overweight for a longer period
We usually gain fat and weight as we age
More…

32. Problems Associated with Excess Body Fat
Body-fat distribution
Greater risk if excess is stored in abdomen rather than in hips and thighs
Other health risk factors
Additional risk factors: high blood pressure, elevated glucose
Lifestyle
Regular exercise can improve body composition and reduce risks associated with being overweight

33. Problems Associated with Too Little Body Fat
What is the lowest body-fat percentage you can have and still maintain a healthy lifestyle? Is it even possible for a woman to have absolutely no body fat?
It is not possible for anyone to have zero body fat
A certain amount of body fat is essential for proper body function
Consequences of low body fat, being underweight:
Fluid imbalances, vitamin and mineral deficiencies, kidney problems
Loss of bone mass, osteoporosis
Reproductive disorders

34. Problems Associated with Too Little Body Fat
If I exercise a lot and my period stops, is that a good thing or a bad thing?
Female athlete triad
Energy availability
Low energy as a result of insufficient calorie intake or increased energy expenditure without increased calorie intake
Menstruation
Amenorrhea
Bone health
Reduced bone density

35. Figure 7-6 The female athlete triad

36. Body Composition and Athletic Performance
I’m a runner. Will decreasing my body fat help make me faster?
Many factors beyond body composition determine performance
All being equal, a decreased level of body fat (that is still in the healthy range) might improve your performance and reduce your susceptibility to performance-related injuries
Too little energy intake and body fat can harm both health and athletic performance
There is no ideal percent body fat for each sport

37. Body Composition, Body Image, and Emotional Wellness
What exactly is body image?
Body image: a mental picture of your own body and how you feel about it
Body dysmorphic disorder (BDD)—preoccupation with imagined defect in appearance
Those with BDD generally have low self-esteem and may engage in compulsive behaviors
More common in women
Muscle dysmorphia—obsessed with the idea that one’s muscularity isn’t enough
More common in men

38. Body Composition, Body Image, and Emotional Wellness
Where does body image come from?
The two key sources of body image (and self-esteem) are family and the media
Family life
Parents criticize the look of their children
Friends and teachers also have an influence
Media
Fashion magazines
TV shows and TV commercials
Social networking

39. Figure 7-7 Average young women versus fashion models and Miss America (1920s–2000s)

40. Body Composition, Body Image, and Emotional Wellness
So we’re supposed to worry about how we look for health reasons but not worry about how we look. How does that work?
What’s important is what’s healthy
Assess your body composition according to health criteria
Avoid comparing yourself to unachievable ideals
Instead, change the way you think about your body
More…

41. Body Composition, Body Image, and Emotional Wellness
Accepting your body:
Focus on the positives
Focus on health and healthy habits
Realistically evaluate which aspects of your body you can change
Set goals that are small and attainable
Avoid negative self-talk about your body
Recognize advertisements from the fitness and beauty industries as what they are
Don’t judge the appearance of others

42. Assessing Body Composition
What’s my ideal weight?
It is hard to define an ideal weight
It depends on other health risk factors
Consider body composition
Percent fat is a better indicator of health status than scale weight

43. Body Mass Index: An Indirect Measure
How do I determine my BMI?
Body mass index (BMI)
One of most common techniques for assessing body fat
Weight(kg) / Height2(m)
BMI does not take into account muscle mass
Waist circumference is used to classify health risks associated with different BMI values

44. Body Mass Index: An Indirect Measure
Is BMI relevant and accurate for both athletes and people who are out of shape?
BMI is only an indirect measure of body composition
It is less accurate for athletes, those with above-average muscle mass, older adults, and certain ethnic groups

45. Figure 7-8 Body mass index

46. Table 7-2 Body Mass Index (BMI) Classification and Disease Risk

47. Methods for Estimating Percent Body Fat
How can you determine body-fat percentages?
Skinfold measurements
Underwater (hydrostatic) weighing
Bioelectrical impedance analysis (BIA)
Air displacement plethysmography
Dual X-ray absorptiometry

48. Table 7-3 Percent-Body-Fat Assessment Methods

49. Methods for Estimating Percent Body Fat
What’s the right percent body fat for me?
This depends on your age, sex, current body composition, and health status
Goals are important too

50. Figure 7-9 Percent-body-fat standards for men and women

51. Methods for Assessing Body-Fat Distribution
Does body shape make any difference when assessing weight and percent body fat?
Body shape makes a difference
Waist circumference
Waist-to-hip ratio
Waist-to-height ratio
These provide some estimate of the risks associated with abdominal fat

52. Making Changes in Body Composition
What’s a good goal for body weight and body fat?
Set appropriate goals based on health assessments, health-risk factors
Apply SMART criteria
Seek medical advice if necessary
Track progress toward goal

53. Making Changes in Body Composition
What’s the best way to lose body fat? What’s the best kind of exercise to lose body fat?
Focus on energy balance
Look at both sides of the energy balance equation
On the “energy out” side of the scale, body composition is best improved by a combination of exercise activities

54. Figure 7-10 Energy balance

55. Making Changes in Body Composition
Why do I lose weight but not body fat?
Weight loss does not automatically equal fat loss
Dieting alone is not the best way to decrease body fat and improve body composition
The best programs for fat loss include increased exercise and modest reductions in energy intake

56. Making Changes in Body Composition
How much exercise do I need to maintain my weight range over time?
To prevent weight gain:
A minimum of 150 minutes per week of moderate-intensity aerobic exercise, or 75 minutes of vigorous-intensity exercise
More…

57. Making Changes in Body Composition
To lose a modest amount of weight or to maintain weight loss:
More is better: 50 minutes a day of moderate-intensity exercise or 25 minutes of high-intensity exercise
To lose significant amounts of weight:
300 minutes per week of moderate-intensity exercise or 150 minutes high-intensity exercise

58. Table 7-4 Approximate Calorie Costs of Selected Physical Activities

59. Making Changes in Body Composition
Why can’t I just focus on improving one part of my body, such as getting rid of unwanted fat in one area?
It is impossible to target one area for fat burning
You can strengthen muscles in one area, but not reduce fat
The exact area in which the body will mobilize fat for fuel depends on a number of factors, including genetics