Transcript Energy Balance Chapter 08x

Energy Balance
and Body
Composition
Chapter 8
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Energy Balance
• Excess energy stored as fat
• Fat used for energy between meals
• Energy balance: energy in = energy out
• Imbalance causes weight changes
• Not simply fat changes
• Classic rule
• 1 pound of fat = 3500 kcalories
• Not exactly correct
• Differs with gender and weight
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Measuring Food Energy
• Direct measure of
food’s energy value
• Bomb calorimeter
• Indirect measure of
energy released
• Oxygen consumed
• kCalorie calculations
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Food Intake
• Hunger
• Physiological response to nerve signals and
chemical messengers
• Hypothalamus
• Influences
• Satiation – signal to stop eating
• Satiety – signal to not to start eating again
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Hunger, Satiation, and Satiety
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Factors That Influence Eating
• Overriding hunger and satiety
• Stress eating
• External cues
• Time of day, availability, sight, taste of food
• Environmental influences
• Examples
• Cognitive influences
• Disordered eating
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Nutrient Composition for
Sustained Satiation and Satiety
•
•
•
•
Protein is most satiating
Low-energy density
High-fiber foods
High-fat foods – strong satiety signals
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The Hypothalamus
• Control center for eating
• Integrates messages
• Energy intake, expenditure, and storage
• Gastrointestinal hormones
• Influence appetite control and energy balance
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Energy Out
• Thermogenesis
• Heat generation
• Measure of energy expended
• Total energy components
•
•
•
•
Basal metabolism
Physical activity
Food consumption
Adaptation
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Basal Metabolism
• Represents about two-thirds of daily energy
• Metabolic activities
• All basic processes of life
• Basal metabolic rate (BMR)
• Variations
• Weight
• Lean tissue
• Resting metabolic rate (RMR)
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Factors that Affect the BMR
Factor
Effect on BMR
Age
Lean body mass diminishes with age, slowing the BMR.a
Height
Growth
In tall, thin people, the BMR is higher.b
In children, adolescents, and pregnant women, the BMR is higher.
The more lean tissue, the higher the BMR (which is why males usually have a higher
BMR than females). The more fat tissue, the lower the BMR.
Fever raises the BMR.C
Stresses (including many diseases and certain drugs) raise the BMR.
Both heat and cold raise the BMR.
Body composition (gender)
Fever
Stresses
Environmental temperature
Fasting/starvation
Malnutrition
Hormones (gender)
Smoking
Caffeine
Sleep
Fasting/starvation lowers the BMR.d
Malnutrition lowers the BMR.
The thyroid hormone thyroxin, for example, can speed up or slow down the BMR.e
Premenstrual hormones slightly raise the BMR.
Nicotine increases energy expenditure.
Caffeine increases energy expenditure.
BMR is lowest when sleeping.
a The
BMR begins to decrease in early adulthood (after growth and development cease) at a rate of about 2 percent/decade.
A reduction in voluntary activity as well brings the total decline in energy expenditure to about 5 percent/decade.
b If two people weigh the same, the taller, thinner person will have the faster metabolic rate, reflecting the greater skin
surface, through which heat is lost by radiation, in proportion to the body's volume (see Figure 8-5, p. 239).
c Fever raises the BMR by 7 percent for each degree Fahrenheit.
d Prolonged starvation reduces the total amount of metabolically active lean tissue in the body, although the decline occurs sooner and to
a greater extent than body losses alone can explain. More likely, the neural and hormonal changes that accompany fasting are
responsible for changes in the BMR.
e The thyroid gland releases hormones that travel to the cells and influence cellular metabolism. Thyroid hormone activity can speed up or
slow down the rate of metabolism by as much as 50 percent.
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Physical Activity
• Voluntary movement of skeletal muscles
• Most variable component of energy
expenditure
• Amount of energy needed
• Muscle mass
• Body weight
• Activity
• Frequency, intensity, and duration
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Thermic Effect of Food
• Acceleration of GI tract functioning in
response to food presence
• Releases heat
• Approximately 10 percent of energy intake
• High-protein foods versus high-fat foods
• Meal consumption time frame
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Adaptive Thermogenesis
• Adapt to dramatically changing circumstances
• Examples
• Extra work done by body
• Amount expended is extremely variable
• Not included in energy requirement
calculations
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Components of Energy
Expenditure
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Estimating Energy
Requirements
• Gender
• BMR
• Growth
• Groups with adjusted
energy requirements
• Age
• Changes with age
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• Physical activity
• Levels of intensity
for each gender
• Body composition
and body size
• Height
• Weight
Ideal Body Weight: Criteria
• The criterion of fashion
• Perceived body image and actual body size
• Damaging behaviors
• Social standards for “ideal”
• Subjective
• Little in common with health
• The criterion of health
• Enough fat to meet basic needs
• Not so much to incur health risks
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Tips for Accepting a Healthy
Body Weight
• Value yourself and others for human attributes other than body weight. Realize that prejudging
people by weight is as harmful as prejudging them by race, religion, or gender.
• Use positive, nonjudgmental descriptions of your body.
• Accept positive comments from others.
• Focus on your whole self including your intelligence, social grace, and professional and scholastic
achievements.
• Accept that no magic diet exists.
• Stop dieting to lose weight. Adopt a lifestyle of healthy eating and physical activity permanently.
• Follow the USDA Food Patterns. Never restrict food intake below the minimum levels that meet
nutrient needs.
• Become physically active, not because it will help you get thin but because it will make you feel good
and improve your health.
• Seek support from loved ones. Tell them of your plan for a healthy life in the body you have been
given.
• Seek professional counseling, not from a weight-loss counselor, but from someone who can help
you make gains in self-esteem without weight as the primary focus.
• Appreciate body weight for its influence on health, not appearance
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Body Mass Index (BMI)
• Measure of relative weight for height
weight (kg)
BMI =
height m 2
• Health-related classifications
• Healthy weight: BMI = 18.5 to 24.9
• Other classifications
• Not a measure of body composition
• Muscular athletes
• Impact of ethnicity
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BMI Table
Underweight
(<18.5)
18
19
20
Healthy Weight
Overweight
Obese
(18.5-24.9)
(25-29.9)
(≥ 30)
21
22
23
24
25
26
27
Height
4"10"
4'11"
5'0"
5'1"
5'2"
5'3"
5'4"
5'5"
5'6"
5'7"
5'8"
5'9"
5'10"
5'11"
6'0"
6'1"
6'2"
6'3"
6'4"
6'5"
6'6"
28
29
30
31
32
33
34
35
36
37
38
39
40
148
153
158
164
169
175
180
186
192
198
203
209
216
222
228
235
241
248
254
261
267
153
158
163
169
175
180
186
192
198
204
210
216
222
229
235
242
249
256
263
269
276
158
163
168
174
180
186
192
198
204
211
216
223
229
236
242
250
256
264
271
277
284
162
168
174
180
186
191
197
204
210
217
223
230
236
243
250
257
264
272
279
286
293
167
173
179
185
191
197
204
210
216
223
230
236
243
250
258
265
272
279
287
294
302
172
178
184
190
196
203
209
216
223
230
236
243
250
257
265
272
280
287
295
303
310
177
183
189
195
202
208
215
222
229
236
243
250
257
265
272
280
287
295
304
311
319
181
188
194
201
207
214
221
228
235
242
249
257
264
272
279
288
295
303
312
319
328
186
193
199
206
213
220
227
234
241
249
256
263
271
279
287
295
303
311
320
328
336
191
198
204
211
218
225
232
240
247
255
262
270
278
286
294
302
311
319
328
336
345
Body weight (pounds)
86
89
92
95
98
102
105
108
112
115
118
122
126
129
132
136
141
144
148
151
155
91
94
97
100
104
107
110
114
118
121
125
128
132
136
140
144
148
152
156
160
164
96
99
102
106
109
113
116
120
124
127
131
135
139
143
147
151
155
160
164
168
172
100
104
107
111
115
118
122
126
130
134
138
142
146
150
154
159
163
168
172
176
181
105
109
112
116
120
124
128
132
136
140
144
149
153
157
162
166
171
176
180
185
190
110
114
118
122
126
130
134
138
142
146
151
155
160
165
169
174
179
184
189
193
198
115
119
123
127
131
135
140
144
148
153
158
162
167
172
177
182
186
192
197
202
207
119
124
128
132
136
141
145
150
155
159
164
169
174
179
184
189
194
200
205
210
216
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124
128
133
137
142
146
151
156
161
166
171
176
181
186
191
197
202
208
213
218
224
129
133
138
143
147
152
157
162
167
172
177
182
188
193
199
204
210
216
221
227
233
134
138
143
148
153
158
163
168
173
178
184
189
195
200
206
212
218
224
230
235
241
138
143
148
153
158
163
169
174
179
185
190
196
202
208
213
219
225
232
238
244
250
143
148
153
158
164
169
174
180
186
191
197
203
209
215
221
227
233
240
246
252
259
BMI and Body Shapes
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Distribution of Body Weights
in US Adults
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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
person
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Ideal (Healthy weight,
average fitness)
Actual
(US average)
20-39
18-21%
26%
40-59
22-25%
29%
60+
24-27%
31%
20-39
23-26%
38%
40-59
28-32%
41%
60+
31-34%
42%
Age (yr)
Male
Female
SOURCE: L. G. Borrud and coauthors. Body composition data for
individuals 8 years of age and older: US population, 1999-2004,
Vital and Health Statistics 11 (2010): 1-87; ACSM's HealthRelated Physical Fitness Assessment Manual, 2nd ed.
(Baltimore, M.D.: Lippincott Williams & Wilkins, 2008), p. 59.
Central Obesity
• Needing less body fat
• Some athletes
• Needing more body fat
• Example groups
• Fat distribution
• Visceral fat
• Central obesity
• Subcutaneous fat
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“Apple” and “Pear” Body
Shapes Compared
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Waist Circumference
• Indicator of fat distribution and central obesity
• Women: greater than 35 inches
• Men: greater than 40 inches
• Waist-to-hip ratio
• Other body composition measurement
techniques
• More precise measures
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Common Methods Used to
Assess Body Fat
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Health Risks Associated with
Body Weight and Body Fat
• Body weight and fat distribution correlate with
disease risk and life expectancy
• Correlations are not causes
• Risks associated with being underweight
• Fighting against wasting diseases
• Menstrual irregularities and infertility
• Osteoporosis and bone fractures
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BMI and Mortality
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Risks Associated With Being
Overweight
• Obesity is a designated disease
• Health risks
• More likely to be disabled in later years
• Costs
• Medical costs
• Lost productivity
• Lives
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Specific Disease Risks
• Cardiovascular disease
• Elevated blood cholesterol and hypertension
• Central obesity
• Diabetes – type II
• Central obesity
• Weight gains and body weight
• Cancer
• Risk of some cancers increases with body weight
• Relationships not fully understood
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Inflammation and the
Metabolic Syndrome
• Change in body’s metabolism
• Cluster of symptoms
• Fat accumulation
• Inflammation
• Elevated blood lipids
• Promote inflammation
• Fit and fat versus sedentary and slim
• Fitness offers many health benefits
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Eating Disorders
Highlight 8
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Eating Disorders, continued
• Three disorders
• Anorexia nervosa
• Bulimia nervosa
• Binge eating disorder
• Prevalence of various eating disorders
• Causes
• Multiple factors
• Athletes and eating disorders
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Female Athlete Triad
• Disordered eating
• Unsuitable weight standards
• Body composition differences
• Risk factors for eating disorders in athletes
• Amenorrhea
• Characteristics
• Osteoporosis
• Stress fractures
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The Female Athlete Triad
Illustrated
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Other Dangerous Practices of
Athletes
• Muscle dysmorphia
• Characteristic behaviors
• Similarities to others with distorted body images
• Food deprivation and dehydration practices
• Impair physical performance
• Reduce muscle strength
• Decrease anaerobic power
• Reduce endurance capacity
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Tips for Combating Eating
Disorders
General Guidelines
• Never restrict food amounts to below those suggested for adequacy by the USDA Food Patterns (see Table
2-2 on p. 44).
• Eat frequently. Include healthy snacks between meals. The person who eats frequently never gets so
hungry as to allow hunger to dictate food choices.
• If not at a healthy weight, establish a reasonable weight goal based on a healthy body composition.
• Allow a reasonable time to achieve the goal. A reasonable loss of excess fat can be achieved at the rate of
about 10 percent of body weight in 6 months.
• Establish a weight-maintenance support group with people who share interests.
Specific Guidelines for Athletes and Dancers
• Replace weight-based goals with performance-based goals.
• Restrict weight-loss activities to the off-season.
• Remember that eating disorders impair physical performance. Seek professional help in obtaining treatment
if needed.
• Focus on proper nutrition as an important facet of your training, as important as proper technique.
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Anorexia Nervosa
• Distorted body image
• Central to diagnosis
• Cannot be self-diagnosed
• Malnutrition
• Impacts brain function and judgment
• Causes lethargy, confusion, and delirium
• Denial
• Levels are high among anorexics
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Characteristics of Anorexia
Nervosa
• Need for self-control
• Impact on body
•
•
•
•
Growth ceases and normal development falters
Changes in heart size and strength
Mineral imbalance
Death can occur from multiple organ system
failure
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Treatment of Anorexia Nervosa
• Multidisciplinary approach
• Food and weight issues
• Relationship issues
• Treatment involves family members
• Different approaches for low, medium, and
high risk patients
• High mortality rate among psychiatric
disorders
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Bulimia Nervosa
• Distinct and more prevalent than anorexia
nervosa
• True incidence difficult to establish
• Secretive nature
• Not as physically apparent
• Common background characteristics of
bulimics
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Characteristics of Bulimia
Nervosa
• Binge-purge cycle
• Lack of control
• Consume food for emotional comfort
• Cannot stop
• Done in secret
• Purge
• Cathartic
• Emetic
• Shame and guilt
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The Vicious Cycle of Restrictive
Dieting and Binge Eating
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Negative
self-perceptions
Restrictive
dieting
Purging
Binge
eating
Stepped Art
Effects of Bulimia Nervosa
• Physical consequences of binge-purge cycle
• Subclinical malnutrition
• Effects
• Physical effects
• Tooth erosion, red eyes, and calloused hands
• High rates of clinical depression and
substance abuse
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Treatment of Bulimia Nervosa
• Discontinuing purging and restrictive diet
habits
• Learn to eat three meals a day
• Plus snacks
• Treatment team
• Length of recovery
• Overlap between anorexia nervosa and
bulimia nervosa
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Diet Strategies for Combating
Bulimia Nervosa
Planning Principles
• Plan meals and snacks; record plans in a food diary prior to eating.
• Plan meals and snacks that require eating at the table and using utensils.
• Refrain from finger foods.
• Refrain from "dieting" or skipping meals.
Nutrition Principles
• Eat a well-balanced diet and regularly timed meals consisting of a variety of foods.
• Include raw vegetables, salad, or raw fruit at meals to prolong eating times.
• Choose whole-grain, high-fiber breads, pasta, rice, and cereals to increase bulk.
• Consume adequate fluid, particularly water.
Other Tips
• Choose foods that provide protein and fat for satiety and bulky, fiber-rich carbohydrates for immediate feelings of
fullness.
• Try including soups and other water-rich foods for satiety.
• Choose portions that meet the definition of "a serving" according to the USDA Food Patterns (pp. 42-43).
• For convenience (and to reduce temptation) select foods that naturally divide into portions. Select one potato, rather
than rice or pasta that can be overloaded onto the plate; purchase yogurt and cottage cheese in individual
containers; look for small packages of precut steak or chicken; choose frozen dinners with measured portions.
• Include 30 minutes of physical activity every day—exercise may be an important tool in defeating bulimia.
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Binge-Eating Disorder
• Periodic binging
• Typically no purging
• Contrast with bulimia nervosa
• Similarities to bulimia nervosa
• Feelings
• Differences between obese binge eaters and
obese people who do not binge
• Behavioral disorder responsive to treatment
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Eating Disorders in Society
• Society plays central role in eating disorders
• Known only in developed nations
• More prevalent as wealth increases
• Food becomes plentiful
• Body dissatisfaction
• Incidence in young people
• Increased steadily since the 1950s
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