sport books publisher1 weight management: finding a healthy balance chapter 12
TRANSCRIPT
Sport Books Publisher 1
Weight Management: Finding a Healthy Balance
Chapter 12
Sport Books Publisher 2
Objectives To discuss the differences between
overweight and obesity and implications for health
To present the concept of caloric balance in weight control
To examine the role of exercise and lifestyle modification in maintaining a healthy weight
To gain familiarity with the consequences of dieting and eating disorders
To set and evaluate personal goals for maintaining a healthy weight
Sport Books Publisher 3
Introduction More than 35% of
Canadian adults are considered overweight or obese
More than 30% of Canadian children are considered overweight or obese
Sport Books Publisher 4
Introduction Physical activity has
been engineered out of day-to-day life
The food environment has become more “toxic” by the day
Eating disorders have emerged due to social pressures to be thin
Sport Books Publisher 5
Energy-Balance Equation
Sport Books Publisher 6
Energy-Balance Equation Body weight is influenced by:
• Energy expended through physical activity • Energy gained through dietary intake
Energy is measured in the form of Calories
This is expressed by the ‘energy-balance equation’
Sport Books Publisher 7
The left side represents Calories consumed The right side represents Calories expended through
physical activity or exercise This situation depicts a balanced energy equation - a
stable weight is achievedCalories consumed = Calories expended
Weight Stability
Sport Books Publisher 8
Calories consumed beyond the body’s needs are stored as fat
Weight gain occurs when energy consumed exceeds energy expended through physical activity
Calories consumed > Calories expended
Weight Gain
Sport Books Publisher 9
Calories expended through physical activity must exceed Calories consumed in food for weight loss to occur
Calories consumed < Calories expended
Weight Loss
Sport Books Publisher 10
Energy-Balance Equation Some people want to put on a few
pounds to look better, or to “bulk up” for athletic events
Healthy weight gain is best achieved through a regimen of increasing (healthy) food intake while participating in a strength-training program to develop lean muscle tissue
Sport Books Publisher 11
Energy Needs of the Body A large amount of energy must be
consumed by the body in order to carry out vital functions such as:• Blood circulation• Respiration• Brain activity
Sport Books Publisher 12
Basal Metabolic Rate (BMR):
The minimum amount of energy the body requires to carry on all vital functions
Sport Books Publisher 13
Basal Metabolic Rate BMR varies throughout the life cycle BMR is generally higher at birth and
increases until age 2, after which it declines as life progresses
Other factors affecting BMR:• Body composition• Physical fitness• Sex• Sleep• Pregnancy• Body temperature• Age
Sport Books Publisher 14
Exercise and Weight Management
The amount of energy expended through physical activity depends on:• Volume of exercise (time, number of
workouts)• Intensity of exercise• Type of exercise
Sport Books Publisher 15
Exercise and Weight Management
In order to efficiently lose weight, exercise should be combined with controlled eating patterns that involve Calorie reduction
Sport Books Publisher 16
Benefits of Exercise Strengthens the heart Improves endurance Provides a means of managing stress Helps prevent osteoporosis Burns Calories Increases metabolic rate
Sport Books Publisher 17
Benefits of ExerciseWeight management is easier
when an exercise regimen is included
Greater lean muscle mass, decreased fat mass, and a higher level of fitness are associated with higher levels of metabolism
A higher metabolic rate allows you to eat more without gaining weight
Sport Books Publisher 18
Body Composition
Sport Books Publisher 19
Body Composition
There are three interrelated aspects of the human physique:• Size (volume, mass, surface area, length)• Structure (skeletal, muscular, fat
arrangement and distribution)• Composition (amount of fat, muscle, bone)
Body composition is one of the major components of physical fitness
Sport Books Publisher 20
Body Composition
Most common method used in body composition analysis is the ‘Two-Component’ model of the body
This model includes:• Lean body mass (LBM)• Fat body mass• Total body fat (TBF)
Sport Books Publisher 21
Lean Body Mass Refers to the ‘non-fat’ or ‘fat-free’
component of the body Includes skeletal muscle, bone, water May represent a biological lower limit
beyond which health is compromised Excessive leanness may increase a
female’s chances of developing amenorrhea (absence of menstruation)
Amenorrhea includes a reduced production of estrogen, which may also increase a female’s chances of developing osteoporosis
Sport Books Publisher 22
Lean body mass is calculated as follows:
LBM = TBM -TBF Lean body mass = Total body mass - Total body fat
TBF is calculated as follows:
TBF = TBM x %BODY FAT 100
Sport Books Publisher 23
Fat Body Mass
Can be divided into two types of fat:
1.Storage Fat (SF)
2.Essential Fat (EF)
Sport Books Publisher 24
1. Storage Fat
Fat that accumulates as adipose tissue
Sport Books Publisher 25
1. Storage Fat
Serves as an energy reserve
Sport Books Publisher 26
1. Storage Fat
Cushions and protects internal organs
Sport Books Publisher 27
1. Storage Fat
Mainly subcutaneous distribution
Sport Books Publisher 28
1. Storage Fat
Average male storage fat = 12%
Sport Books Publisher 29
1. Storage Fat
Average female storage fat = 15%
Sport Books Publisher 30
1. Storage Fat
Excess fat is associated with numerous health
problems
Sport Books Publisher 31
2. Essential Fat
Required for normal physiological functioning
Sport Books Publisher 32
2. Essential FatPresent in 1. Bone marrow
2. Heart
3. Lungs
4. Liver
5. Spleen
6. Kidneys
7. Intestines
8. Muscle
9. Central nervous system
Sport Books Publisher 33
2. Essential Fat
Comprises about 3% of body weight for the
average male
Sport Books Publisher 34
2. Essential Fat
Comprises about 12% of body weight for the
average female
Sport Books Publisher 35
2. Essential Fat
Gender-specific essential fat is located in the mammary glands, pelvic region, and is involved in hormone-related functions and pregnancy
Sport Books Publisher 36
Measuring Body Fat
Direct Measurement
Indirect Measurement
Sport Books Publisher 37
Direct Measurement
Measuring Body Fat
Involves grinding tissue
Measures fat via chemical analysis
Impractical for living organisms
Used on cadavers
Sport Books Publisher 38
Indirect Measurement
Measuring Body Fat
Skinfold calipers
Hydrostatic weighing
Bod-Pod Bioelectrical
impedance DEXA
Sport Books Publisher 39
Skinfold Calipers
Sport Books Publisher 40
Skinfold Calipers Measures skinfold thickness to predict
or estimate total body fat Based on the assumption that
subcutaneous fat is directly related to total body fat
Accuracy is ± 3% when performed correctly
Sport Books Publisher 41
Hydrostatic Weighing
Sport Books Publisher 42
Hydrostatic Weighing Determines body density to be used in
further equations that calculate percent body fat
Based on Archimedes’ principle of water displacement - an object submerged in water yields a buoyant force equal to the weight of water displaced
Sport Books Publisher 43
Hydrostatic Weighing Bone and muscle have a greater density than
water Fat is less dense than water Thus, a person’s relative buoyancy is
positively correlated with body fat That is, a person with a higher body fat
percentage is less dense (weighs less in water) than a lean individual
Sport Books Publisher 44
Hydrostatic Weighing To calculate body fat, the
following measurements are needed:
1. Body weight on land2. Underwater body weight3. Water density at the
performed temperature4. Residual lung volume
More accurate measure
Sport Books Publisher 45
The Bod-Pod
Sport Books Publisher 46
The Bod-Pod Very expensive method Very accurate measure May facilitate measuring large or
heavy individuals because it does not involve underwater submersion
Sport Books Publisher 47
Bioelectrical Impedance (BIA)
Sport Books Publisher 48
Bioelectrical Impedance (BIA) Based on differences in electrical
conductivity between fat-free mass and fat mass
Sport Books Publisher 49
Bioelectrical Impedance (BIA) Percent body fat is calculated from
measures of body density determined by passing an electrical current through the body
Sport Books Publisher 50
Bioelectrical Impedance (BIA)BIA is influenced by
the subject’s hydration level
The more hydrated one is, the leaner the BIA measurement will be
Sport Books Publisher 51
Dual Energy X-Ray Absorptiometry (DEXA)
Sport Books Publisher 52
Dual Energy X-Ray Absorptiometry (DEXA)
Can be used to determine body composition Can also measure bone density (bone
mineral content)
Sport Books Publisher 53
Body Mass Index (BMI) Can be used as an easy, inexpensive method
for determining an individual’s healthy body weight
Considers weight (kg) and height (m)
BMI = Weight (kg) [Height (m)]2
A BMI nomogram can also be used to
determine BMI, it looks like this…
Sport Books Publisher 54
Body Mass Index (BMI)
Sport Books Publisher 55
Three general ranges:1. Underweight2. Healthy or Acceptable Weight3. Overweight
• Severe Overweight• Morbid Obesity
BMI score > 30 is classified as obese and associated with an increased risk of developing health problems
Risk of developing health problems is also associated with BMI’s classified as being within the underweight range
Body Mass Index (BMI)
Sport Books Publisher 56
Body Mass Index (BMI)
The BMI is intended for men and women aged 20-65
It is not intended for:1. Babies2. Children3. Teenagers4. Pregnant women5. Very muscular people, such as athletes
Sport Books Publisher 57
Somatotyping The human body
is composed of:1. Roundness2. Muscularity3. Linearity Various sports
require sport-specific body types for achieving optimal performance
Sport Books Publisher 58
Somatotyping Endomorphs exhibit a round appearance
and a predominance of the gut and visceral organs
Common sports that require this body type include wrestling, weight-lifting, and throwing events
Sport Books Publisher 59
Somatotyping Mesomorphs exhibit a predominance of
muscle Common sports that require this body
type include body building, swimming, and decathlon
Sport Books Publisher 60
Somatotyping Ectomorphs exhibit a predominance of
linearity and tend to be tall and thin Common sports that require this body
type include marathon, basketball, horse-racing, and high-jump
Sport Books Publisher 61
Obesity
Sport Books Publisher 62
Obesity
Having an excess of body fat beyond some particular standard
Sport Books Publisher 63
Obesity To be classified as obese (ages 17-
50yrs):• Body fat percentage > 20% for
males• Body fat percentage > 30% for
females Obesity has reached epidemic
proportions in the Western world 35% of Canadian men and 27% of
Canadian women are considered obese
Sport Books Publisher 64
Obesity Involves many factors:
1. Environmental2. Social3. Psychological4. Genetic
Sport Books Publisher 65
Obesity There are numerous health problems
associated with obesity, including:
1. Coronary heart disease2. Stroke3. Hypertension4. Diabetes5. Osteoarthritis6. Some cancers
Sport Books Publisher 66
Creeping Obesity
Obese individuals are often viewed as gluttonous
They generally do NOT consume large amounts of calories
Physically active individuals have been shown to consume more calories than obese individuals
Sport Books Publisher 67
Creeping Obesity Obesity is often the
result of too little activity rather than overeating
This is what leads to ‘creeping obesity’
Creeping obesity is the result of a long-term change in energy balance that results in gradual fat gain over a period of time
Sport Books Publisher 68
Misleading Norms Weight norms must be interpreted with
caution Overweight does not necessarily mean
obese Body composition is important when
making this distinction Being ‘overweight’ because of a large
lean mass is not associated with the health problems linked to obesity
Sport Books Publisher 69
Weight-Loss Industry Has become a billion-dollar industry as
obesity rates rise Many fad diets exist such as
• High-protein, low-carbohydrate diets• High-carbohydrate, low-protein diets• Limited food choice diets
Most of these diets are ineffective and CAN BE HARMFUL
Sport Books Publisher 70
Weight-Loss Industry Following
Canada’s Food Guide and engaging in regular physical activity appears to be the best approach to weight management
Sport Books Publisher 71
Consequences of Dieting
Cultural pressures to be thin and the stigma of being overweight have resulted in many young people engaging in dieting and abnormal eating behaviours
Sport Books Publisher 72
Consequences of Dieting Chronic dieting can
lead to:1. Retardation of
physical growth2. Menstrual
irregularities in females
3. Lowered metabolic rate
4. Development of eating disorders
Sport Books Publisher 73
Eating Disorders
Sport Books Publisher 74
Eating Disorders Two major eating disorders within the
general population:
1. Anorexia Nervosa
2. Bulimia Nervosa
A related syndrome is known as ‘Binge Eating Disorder’ (BED)
Eating disorders also occur in male and female athletes
Sport Books Publisher 75
Eating Disorders Factors involved in the development of
eating disorders include:• Dissatisfaction with body image• Distortions in thinking• Perfectionist beliefs• Excessive self-criticism• Fear of fat• Excessive dieting• Preoccupation with food
Sport Books Publisher 76
Anorexia Nervosa
Failing to eat an adequate amount of food to maintain a reasonable body weight
Avoidance of food Engaging in
excessive vigorous exercise
Sport Books Publisher 77
Anorexia Nervosa Symptoms Typically, weigh less
than 85% of normal weight
Dry skin Amenorrhea Reduced bone mass Brittle nails Carotene pigmentation
(yellowish appearance of the palms and soles of the feet)
Sport Books Publisher 78
Bulimia Nervosa Characterized by
continual episodes of binge eating followed by purging
A binge involves eating large amounts of food in a discrete period of time
After a binge, vomiting is induced and/or laxatives are used
May also involve excessive exercise as a form of purging
Sport Books Publisher 79
Bulimia Nervosa Symptoms Body weight is often normal Secretive eating patterns Nervous or agitated behaviour
immediately after eating Loss or gain of extreme amounts of
weight
Sport Books Publisher 80
Binge Eating Disorder (BED) Involves ingesting
large amounts of food without purging
Is encouraged in some sports such as sumo wrestling and football
Leads to obesity in most cases
Sport Books Publisher 81
Eating Disorders Among Athletes
Athletes competing in sports with weight classes try to “make weight” in lower weight classes to gain a competitive edge
Often stems from a performance objectives rather than issues of self-esteem or body image
Sports include wrestling, horse racing (jockey), rowing, boxing, weight-lifting, etc.