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C HAPTER
11
Achieving and
Maintaining
a Healthful Body
Weight
and In Depth
Copyright © 2012 Pearson Education, Inc.
What Is a Healthful Body Weight?
A healthful weight
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Is appropriate for your age
Is maintained without constant dieting
Is acceptable to you
Is based on family history of body shape and
weight
 Promotes good eating habits and allows for regular
physical activity
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What Is a Healthful Body Weight?
Underweight: having too little body fat to maintain
health
Overweight: having a moderate amount of excess
body fat
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What Is a Healthful Body Weight?
Obesity: having an excess of body fat that adversely
affects health
Morbid obesity: body weight exceeding 100% of
normal, creating a very high risk for serious health
complications
© 2012 Pearson Education, Inc.
Evaluating Body Weight
A person’s actual weight is not the only factor to
consider
Determining if a person’s body weight is healthful
should include
 Determining the body mass index (BMI)
 Measuring body composition
 Assessing the pattern of fat distribution
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Evaluating Body Weight
Body mass index
 Expresses the ratio of a person’s weight to the
square of his or her height
 BMI = weight (kg)/height (m)2
 BMI values below 18.5 or above 30 have increased
risks of health problems
 BMI results are distorted in people with high
muscle mass (athletes and lactating women)
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BMI Chart
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BMI Classifications:
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Body Mass Variations
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Evaluating Body Weight
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Evaluating Body Weight
Body composition
 Measurement of body fat and lean muscle mass
 Can be measured by
 Underwater weighing
 Skinfold measurements
 Bioelectrical impedance analysis
 Dual-energy x-ray absorptiometry (DXA)
 Bod Pod®
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Evaluating Body Weight
Fat distribution pattern
 Measured by waist-to-hip ratio and waist
circumference
 Apple-shaped fat patterning—upper body
 Increased risk for chronic diseases (type 2 diabetes,
heart disease, hypertension)
 Pear-shaped fat patterning—lower body
 No significant increased risk for chronic diseases
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Evaluating Body Weight
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Gaining or Losing Weight
Whether a person gains or loses weight depends on
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Energy intake versus energy expenditure
Genetic factors
Composition of the diet
Childhood weight
Behavioral factors
Social factors
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Energy Balance
Energy balance
 Occurs when energy intake = energy expenditure
 Energy intake = kcal from food
 Energy expenditure
 Energy expended at rest (basal metabolic rate)
 Physical activity
 Thermic effect of food
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Energy Balance
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Components of Energy Expenditure
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Energy Balance
Basal metabolic rate (BMR)
 Energy expended to maintain basal, or resting,
functions of the body
 60–75% of total energy expenditure
 More lean tissue increases your BMR
 BMR decreases with age, 3–5% per decade after
age 30
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Energy Balance
Physical activity
 15–35% of daily energy expenditure
 Factors that influence energy expended
 The more muscle groups used, the greater the energy
expenditure
 Intensity
 Duration
 Body size
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Energy Balance
Thermic effect of food (TEF)
 Energy expended to digest, absorb, transport,
metabolize, and store food
 5–10% of total expenditure
 Lowest for fat and highest for protein
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Composition of the Diet
The thermal effect of the diet can affect energy
balance
 Dietary fat has minimal thermal effect
 It takes more energy to digest, absorb, transport,
and metabolize protein and carbohydrates;
therefore, they are more energy expensive to
process
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Energy Balance
Energy cost of physical activity
 Represents about 15–35% of our total daily energy
output
 Is highly variable
 Includes both lower-intensity and higher-intensity
activities
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Genetic Factors
Genetic factors account for about 25% of a person’s
body fat
Different ideas have been suggested to explain the
impact of genetics on body fat
 Thrifty gene theory
 Set-point theory
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Factors Affecting Basal Metabolic Rate
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Genetic Factors
Thrifty gene theory
 Proposes that a gene (or genes) causes people to be
energetically thrifty
 Proposes that people with this gene expend less
energy than other people and therefore gain weight
 A “thrifty gene” has not been identified
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Genetic Factors
Set-point theory
 Proposes that each person’s weight stays within a
small range (set point)
 The body compensates for changes in energy
balance and keeps a person’s weight at his or her
set point
 Can change with time, as diet and activity levels
vary over a long period of time
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Physiologic Factors
 Hunger and satiety
 Specific proteins and hormones
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Leptin & Peptide YY or PYY: Reduces appetite
Ghrelin: Increases appetite
Brown adipose tissue
Serotonin
Cholecystokinin (CKK)
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Physiologic Factors
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Blood glucose levels
Stomach expansion
Nutrient absorption from the small intestine
Beta-endorphins
Neuropeptide Y
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Proteins
Leptin
 Leptin is a hormone produced by fat cells that
causes reduced food intake, reduced weight, and
decreased body fat in mice
 Leptin is controlled by the ob gene
 Mutation of the ob gene in mice causes reduced
levels of leptin, leading to increased food intake
and reduced energy output
 The role of leptin in human obesity is being studied
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Proteins
Ghrelin
 Protein synthesized in the stomach
 Stimulates appetite by acting on the hypothalamus
Peptide YY
 Produced in the GI tract
 Decreases appetite
 Obese people have lower levels when fasting
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Behavioral Factors
Food choices
 The composition of a person’s diet should remain
balanced
Hunger versus appetite
 Hunger: physiologic drive or need to eat
 Appetite: a psychological desire to eat, often in the
absence of hunger
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Cultural and Economic Factors
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Cultural customs
Changes in work and leisure activity levels
Larger body size acceptance/cultural norms
Lack of access to healthcare and health information
Lack of access to affordable, healthful foods
Lack of access to positive role models
Personal safety issues
Transportation issues
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Psychological and Social Factors
Psychosocial factors influencing our diet include
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Family or cultural traditions
Promotion of overeating
Holidays and celebrations
Easy access to high-fat foods
Less physically active lifestyles
Societal expectations of the “perfect” body
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Hot Dogs, Apple Pie, and Weight
•
Americans spend $60
billion annually on weightloss, but are gaining
weight rather than losing it
•
Only 5-10% of people
who lose weight keep it
off
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The Business of Weight Loss
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More than 29,000 weightloss products and services
are available
•
Almost none of them work
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Lack of Consumer Protection
•
No laws require a weight-loss product must be
effective in order to be sold
•
Weight-loss products are not tested for safety
before they reach the market – some cause serious
problems, even death
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Weight Loss vs Weight Control
•
Diets and weight loss do not cure overweight
 People return to old habits, regain weight
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Improved and enjoyable eating and exercise habits
are needed to keep excess weight off
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Weight Loss vs Weight Control
•
Diets and weight loss do not cure overweight
 People return to old habits, regain weight
•
Improved and enjoyable eating and exercise habits
are needed to keep excess weight off
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Fad Diets
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Weight Regain With Popular Diets
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People can’t stick to difficult or unpleasant
popular diets long – then weight is regained
KNOW THIS:
The best way to sustain weight loss is by making
small, easy changes to diet and physical activities
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Achieve and Maintain Healthful Weight
Healthful weight change requires
 Gradual change in energy intake
 Regular and appropriate physical exercise
 Application of behavior modification techniques
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Achieve and Maintain Healthful Weight
Effective weight loss should include
 Following recommended serving sizes
 Reduced intake of high-fat and high-energy foods
 Regular physical exercise
 To increase energy expenditure
 To increase BMR
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Achieve and Maintain Healthful Weight
Diet plans to avoid
 Fad diets—they do not result in long-term healthful
weight change
 Promoters claim the program is based on some new
discovery
 Rapid weight loss (>2 lbs/wk) with no exercise
 Special foods only available from promoter
 Rigid and limited menu
 Diets that over- or underemphasize specific,
narrowly defined nutrients as the key to weight loss
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Weight-Loss Strategies
Guidelines for successful weight loss
1. Set realistic goals
 Specific
 Reasonable
 Measurable
 Monitor progress regularly
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Weight-Loss Strategies
2. Eat smaller portions of lower-fat foods
 Follow serving sizes in MyPyramid
 Reduce consumption of high-fat and high-energy
foods
 Consume foods low in energy density
3. Participate in regular physical activity
 Critical for long-term maintenance of weight loss
© 2012 Pearson Education, Inc.
Behavior Modification
Successful weight loss requires behavior
modification
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Eat only at set times in one location
Keep a log of food consumed
Avoid buying problem foods
Serve food on smaller dishes
Eat small, regular meals throughout the day
Chew slowly and stop eating when you feel full
Share food with others
Do not purchase foods from vending machines
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Successful Weight Loss
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Gradual Weight Loss
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Underweight
Underweight
 BMI below 18.5 kg/m2
 Increases the risk of infections and illness and can
even be fatal
 Can be just as unhealthy as overweight
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Food is medicine
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Achieve and Maintain Healthful Weight
Effective weight gain should include
 Eating 500 to 1,000 extra kcal/day
 Eating frequently throughout the day
 Maintaining a balanced diet, limiting fat intake to
15–30% of total energy intake
 Avoiding tobacco products, which depress appetite
and increase BMR
 Regular exercise with resistance training
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In Depth: Obesity
Chronic diseases linked to obesity include
 Hypertension
 High cholesterol, triglycerides, and LDL-cholesterol
 Type-2 diabetes
 Heart disease
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In Depth: Obesity
Chronic diseases linked to obesity include
 Stroke
 Gallbladder disease
 Certain cancers
 Depression
 Cognitive decline
PLAY
Obesity Rates
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In Depth: Obesity
Obesity and morbid obesity
 Obesity: BMI from 30 to 39.9 kg/m2
 Morbid obesity: weight that exceeds 100% of
normal
 Five of the nine leading causes of death in the
United States are associated with obesity
 A multifactorial disease—many things cause
obesity
 Metabolic syndrome—a cluster of risk factors
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In Depth: Obesity
Factors that can influence the chance of developing
obesity include
 Genetics
 Physiology
 Overweight and obesity in childhood
 Social factors
 Physical factors such as thyroid levels, or use of
certain prescription medications
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In Depth: Obesity
Treatments for obesity may include
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Low-calorie diet and regular exercise
Lifestyle changes
Prescription medications (for some)
Surgery
 Gastroplasty
 Gastric bypass
 Gastric banding
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In Depth: Obesity
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ABC News Nutrition Video
Diet Dream Drug: Hope or Hype: Pros and Cons of Alli
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ABC News Nutrition Video
Can You Be Slim and Obese? Hidden Risk of Normal Weight Obesity
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ABC News Nutrition Video
Calorie Count: Eat by the Numbers
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ABC News Nutrition Video
Low-Cost, High-Impact Solutions
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