1. Weight Management: Finding a Healthy Balance
Chapter 12
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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
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3. Introduction
More than 35% of Canadian adults are considered overweight or obese
More than 30% of Canadian children are considered overweight or obese
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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
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5. Energy-Balance Equation
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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’
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7. Weight Stability 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 achieved
Calories consumed = Calories expended
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8. Weight Gain
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
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9. Weight Loss
Calories expended through physical activity must exceed Calories consumed in food for weight loss to occur
Calories consumed < Calories expended
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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
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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
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12. Basal Metabolic Rate (BMR):
The minimum amount of energy the body requires to carry on all vital functions
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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
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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
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15. Exercise and Weight Management
In order to efficiently lose weight, exercise should be combined with controlled eating patterns that involve Calorie reduction
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16. Benefits of Exercise Strengthens the heart Improves endurance
Provides a means of managing stress
Helps prevent osteoporosis
Burns Calories
Increases metabolic rate
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17. Benefits of Exercise
Weight 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
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18. Body Composition
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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
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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)
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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
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22. LBM = TBM -TBF Lean body mass = Total body mass - Total body fat
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
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23. Can be divided into two types of fat: Storage Fat (SF)
Fat Body Mass
Can be divided into two types of fat:
Storage Fat (SF)
Essential Fat (EF)
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24. Fat that accumulates as adipose tissue
1. Storage Fat
Fat that accumulates as adipose tissue
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25. Serves as an energy reserve
1. Storage Fat
Serves as an energy reserve
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26. Cushions and protects internal organs
1. Storage Fat
Cushions and protects internal organs
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27. Mainly subcutaneous distribution
1. Storage Fat
Mainly subcutaneous distribution
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28. Average male storage fat = 12%
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29. Average female storage fat = 15%
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30. Excess fat is associated with numerous health problems
1. Storage Fat
Excess fat is associated with numerous health problems
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31. Required for normal physiological functioning
2. Essential Fat
Required for normal physiological functioning
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32. 2. Essential Fat Present in Bone marrow Heart Lungs Liver Spleen
Kidneys
Intestines
Muscle
Central nervous system
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33. Comprises about 3% of body weight for the average male
2. Essential Fat
Comprises about 3% of body weight for the average male
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34. Comprises about 12% of body weight for the average female
2. Essential Fat
Comprises about 12% of body weight for the average female
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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
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36. Measuring Body Fat Direct Measurement Indirect Measurement
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37. Measuring Body Fat Involves grinding tissue
Measures fat via chemical analysis
Impractical for living organisms
Used on cadavers
Direct
Measurement
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38. Measuring Body Fat Skinfold calipers Hydrostatic weighing Bod-Pod
Bioelectrical impedance
DEXA
Indirect
Measurement
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39. Skinfold Calipers
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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
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41. Hydrostatic Weighing
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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
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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
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44. Hydrostatic Weighing
To calculate body fat, the following measurements are needed:
Body weight on land
Underwater body weight
Water density at the performed temperature
Residual lung volume
More accurate measure
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45. The Bod-Pod
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46. The Bod-Pod Very expensive method Very accurate measure
May facilitate measuring large or heavy individuals because it does not involve underwater submersion
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47. Bioelectrical Impedance (BIA)
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48. Bioelectrical Impedance (BIA)
Based on differences in electrical conductivity between fat-free mass and fat mass
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49. Bioelectrical Impedance (BIA)
Percent body fat is calculated from measures of body density determined by passing an electrical current through the body
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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
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51. Dual Energy X-Ray Absorptiometry (DEXA)
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52. Dual Energy X-Ray Absorptiometry (DEXA)
Can be used to determine body composition
Can also measure bone density (bone mineral content)
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53. BMI = Weight (kg) [Height (m)]2 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…
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54. Body Mass Index (BMI)
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55. Body Mass Index (BMI) Three general ranges: Underweight
Healthy or Acceptable Weight
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
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56. Body Mass Index (BMI) The BMI is intended for men and women aged 20-65
It is not intended for:
Babies
Children
Teenagers
Pregnant women
Very muscular people, such as athletes
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57. Somatotyping The human body is composed of: Roundness Muscularity
Linearity
Various sports require sport-specific body types for achieving optimal performance
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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
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59. Somatotyping Mesomorphs exhibit a predominance of muscle
Common sports that require this body type include body building, swimming, and decathlon
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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
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61. Obesity
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62. Having an excess of body fat beyond some particular standard
Obesity
Having an excess of body fat beyond some particular standard
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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
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64. Obesity Environmental Social Psychological Genetic
Involves many factors:
Environmental
Social
Psychological
Genetic
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65. Obesity Coronary heart disease Stroke Hypertension Diabetes
There are numerous health problems associated with obesity, including:
Coronary heart disease
Stroke
Hypertension
Diabetes
Osteoarthritis
Some cancers
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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
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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
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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
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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
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70. Weight-Loss Industry
Following Canada’s Food Guide and engaging in regular physical activity appears to be the best approach to weight management
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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
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72. Consequences of Dieting
Chronic dieting can lead to:
Retardation of physical growth
Menstrual irregularities in females
Lowered metabolic rate
Development of eating disorders
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73. Eating Disorders
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74. Eating Disorders
Two major eating disorders within the general population:
Anorexia Nervosa
Bulimia Nervosa
A related syndrome is known as ‘Binge Eating Disorder’ (BED)
Eating disorders also occur in male and female athletes
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75. Eating Disorders Dissatisfaction with body image
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
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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
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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)
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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
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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
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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
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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.
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