CHAPTER 13 Achieving and Maintaining a Healthful Weight.pptx

The Science of Nutrition
Fifth Edition
Chapter 13
Achieving and Maintaining
a Healthful Body Weight
Copyright © 2020 Pearson Education, Inc. All Rights Reserved
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What Is a Healthful Body Weight? (1 of 3)
• Appropriate for age and physical development
• Achievable and sustainable without constant dieting
• Compatible with normal blood pressure, lipid levels, and
glucose tolerance
• Based on genetic background and family history of body
shape and weight
• Supported by good eating habits and allows for regular
physical activity
• Acceptable to you

Evaluating Body Weight
• 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

Body Mass Index
• Represents the ratio of a person’s weight to the square of
his or her height
• 2
BMI = weight (kg)/heigh (m)
t
• a
2
BMI = weight lbs /height inch
[ ( ) ( ) ]
es × 703
• BMI values below 18.5 or above 30 have increased health
risks

Figure 13.1

• Underweight:
– BMI less than 2
18.5 kg/m
– Having too little body fat to maintain health
• Normal weight:
– BMI between 2
18.5 and 24.9 kg/m
• Overweight:
– BMI between 2
25 and 29.9 kg/m
– Having a moderate amount of excess body fat

• Obese:
– Class 1: BMI between 30 and 2
34.9 kg/m
– Class 2: BMI between 35 and 2
39.9 kg/m
– Having an excess of body fat that adversely affects
health, increasing disease risk significantly
• Morbid obesity:
– Class 3: BMI greater or equal to 2
40 kg/m
– Body weight exceeding 100% of normal, a very high
risk for serious health consequences

Limitations of BMI
• Not an indication of body composition
• Not appropriate for use in older adults (bone and muscle
loss) and children (bone and muscle growth), athletes,
pregnant, and lactating women
• Doesn’t account for physical and metabolic differences in
ethnic backgrounds

Body Composition
• Estimate body composition by assessing body fat and
lean body mass with
– Underwater weighing
– Skinfold measurements
– Bioelectrical impedance analysis
– Near-infrared reactance
– Dual-energy X-ray absorptiometry (DXA)
– Bod Pod™
• Norms vary according to gender and fitness
• Obesity: >25% for men and >32% for women

Figure 13.2

ABC News Video: Overweight and
Healthy?

Fat Distribution Pattern (1 of 2)
• Apple-shaped fat patterning: upper body
– Increased risk for chronic diseases
– Men tend to store fat in the abdominal region
• Pear-shaped fat patterning: lower body
– No significant increased chronic disease risk
– Women tend to store fat in the lower body

Fat Distribution Pattern (2 of 2)
• Abdominal fat increases risk for chronic disease
• Waist circumference
– Men: above 40 inches (or 102 centimeter)
– Women: above 35 inches (or 88 centimeter)

Figure 13.3

Energy Balance
• Fluctuations in weight depend on:
– Energy intake and energy expenditure
• Energy balance equation
– Energy intake = energy expenditure
– Energy intake is kcal from food and beverages
– Energy expenditure is energy expended at rest and
during physical activity

Focus Figure 13.4

Energy Intake
• Calculating the energy that is in a particular food
– Carbohydrate is 4 kilocalories/gram
– Protein is 4 kilocalories/gram
– Fat is 9 kilocalories/gram
– Alcohol is 7 kilocalories/gram
• 1 cup of quick oatmeal has 142 kilocalories
– 6 grams protein × 4 kilocalories/gram = 24 kilocalories
– 25 grams carbohydrate × 4 kilocalories/gram = 100 kilocalories
– 2 grams fat × 9 kilocalories/gram = 18 kilocalories
– Total kilocalories = 24 kilocalories + 100 kilocalories + 18 kilocalories = 142 kilocalories

Energy Expenditure (1 of 4)
• Energy is expended to maintain basic body functions and
to perform activities
• Total 24-hour energy expenditure is composed of three
components:
– Basal metabolic rate (BMR)
– Thermic effect of food (TEF)
– Energy cost of physical activity

Figure 13.5

• Direct calorimetry is a method that measures the
amount of heat the body releases
– Requires airtight chamber, rarely used in humans
• Indirect calorimetry estimates energy expenditure by
measuring oxygen consumption and carbon dioxide
production
– Less expensive and more accessible

• Indirect calorimetry can be used to measure the components of
energy expenditure

Basal Metabolic Rate (BMR)
• Energy expended to maintain basal (resting) functions of
the body
• Includes respiration, circulation, maintaining body
temperature, new cell synthesis, secretion of hormones,
and nervous system activity
• Primary determinant of BMR is the amount of lean body
mass
• Varies widely among people

Table 13.1 Factors Affecting Basal
Metabolic Rate (BMR)
Factors That Increase BMR Factors That Decrease BMR
Higher lean body mass Lower lean body mass
Greater height (more surface area) Lower height
Younger age Older age
Elevated levels of thyroid hormone Depressed levels of thyroid hormone
Stress, fever, illness Starvation, fasting or very-low-Calorie diets
Male gender Female gender due to decreased lean tissue
Pregnancy and lactation Blank
Certain drugs, such as stimulants, caffeine, and
nicotine
Certain medications, such as steroids used for
asthma

• Thermic effect of food (TEF)
– Energy expended to process food
– About 5–10% of the energy content of a meal
• Energy cost of physical activity
– About 15–35% of total daily energy output
– Non-exercise activity thermogenesis (NEAT) is
energy expended for activities above BMR and TEF
but excludes sporting activities, includes
spontaneous physical activity such as fidgeting and
shifting

Table 13.2 Energy Costs of Various
Physical Activities
Activity Intensity Energy Cost (kilocalorie/kilogram
body weight/minute)
Sitting, studying (including reading or writing) Light 0.022
Cooking or food preparation (sitting or standing) Light 0.033
Walking (e.g., to neighbor’s house) Light 0.042
Stretching—Hatha yoga Moderate 0.042
Cleaning (dusting, straightening up, vacuuming, changing
linen, carrying out trash)
Moderate 0.058
Weight lifting (free weights, Nautilus, or universal type) Light or moderate 0.050
Bicycling, 10 milesperhour Leisure (work or pleasure) 0.067
Walking, 4 milesperhour (brisk pace) Moderate 0.083
Aerobics Low impact 0.083
Weight lifting (free weights, Nautilus, or universal type) Vigorous 0.100
Bicycling, 12 to 13.9 milesperhour Moderate 0.133
Running, 5 mph (12 minutes per mile) Moderate 0.138
Running, 6 mph (10 minutes per mile) Moderate 0.163
Running, 8.6 mph (7 minutes per mile) Vigorous 0.205
Source: Data from The Compendium of Physical Activities Tracking Guide. Healthy Lifestyles Research Center, College
of Nursing & Health Innovation, Arizona State University.

Genetic Factors
• Influence height, weight, body shape, and metabolic rate
• BMI based on genetic factors and nongenetic,
environmental, and lifestyle factors (10 to 90%)
• Different ideas have been suggested to explain the
impact of genetics on body fat
– FTO gene
– Thrifty gene hypothesis
– Set-point hypothesis
– Protein leverage hypothesis
– Drifty gene hypothesis

Fat Mass and Obesity (FTO)-Associate
Gene
• Common gene: 44–65% of people estimated to have at
least one copy
• May stimulate excessive food intake and reduce the
feeling of satiety
• Physical activity can reduce the influence of the gene on
obesity risk

Thrifty Gene Theory
• Proposes that a gene (or genes) causes people to be
energetically thrifty
• People with this gene expend less energy at rest than
other people at rest
• Protects from starvation during times of extreme food
shortages
• A “thrifty gene” has not been identified

Set-Point Theory
• Suggests that body weight stays within a narrow range
(set point)
• Compensates for changes in energy balance and keeps
a person’s weight at his or her set point

Protein Leverage Hypothesis
• Suggests that humans have evolved to have fixed daily
dietary protein target for optimal physiological functioning
• Proposed that more kcal are consumed because the
body is tying to meet genetically programmed protein
target

Drifty Gene Hypothesis
• Suggests an observation that in the current food
environment, some people become obese, but others do
not
• Proposes the effect is due to random mutation and drift in
the genes that control the upper limit of body fatness

Metabolic Factors Influence Weight
• Relatively low metabolic rate
• Low level of spontaneous physical activity
• Low sympathetic nervous system activity
• Low fat oxidation
• Abnormally low level of thyroid hormone
• Certain prescription medications

Physiologic Factors (1 of 2)
• Hunger and satiety
• Proteins affect the regulation of appetite and storage of
body fat
– Leptin: hormone produced by adipose tissue, acts to
reduce food intake
– Ghrelin: hormone produced in stomach, stimulates
appetite
– Peptide YY (PYY): protein produced in GI tract,
decreases appetite
– Uncoupling proteins in brown adipose tissue
increase energy expenditure

Physiologic Factors (2 of 2)
• Increase satiety (or decrease food intake)
– Hormones: serotonin, cholecystokinin (CCK)
– Increase in blood glucose levels after meal
– Stomach expansion
– Nutrient absorption from the small intestine
• Decrease satiety (or increase food intake)
– Hormones: beta-endorphins
– Neuropeptide Y
– Decreased blood glucose levels

Sociocultural Factors
• Learned food preferences
• Religious beliefs
• Fast-food culture
• Inactive lifestyle
• Economic status
• Pressures to maintain ideal body weight

Social Factors
• Appetite: psychological drive to eat
• Meal timing and size: portion distortion
• Sight and fragrance of foods
• Mood and depression
• Barriers to physical activity
• Technological lifestyle
• Social pressures and underweight

Obesity and Chronic Diseases
• Linked to many chronic diseases:
– CVD
– Hypertension
– Dyslipidemia
– Diabetes
– Gallbladder disease
– Osteoarthritis
– Sleep apnea
– Some cancers
– Depression
– Alzheimer’s, dementia, and cognitive decline

Abdominal Obesity
• Central adiposity is characterized by large amount of
visceral fat stored in abdomen
• Releases excess fatty acids and adipokines, cell
signaling proteins secreted by adipose tissues, are pro-
inflammatory

Metabolic Syndrome (1 of 2)
• A cluster of factors increases risk for heart disease, type
2 diabetes, and stroke:
– Abdominal obesity (waist circumference ≥40 inches
for men, 35 inches for women)
– Triglyceride levels (≥150 milligram/deciLiter)
– HDL cholesterol levels (<40 milligram/deciLiter in men and 50
milligram/deciLiter in women)
– Blood pressure (≥130/85 millimeter Hg)
– Fasting blood glucose ≥100 milligram/deciLiter

Metabolic Syndrome (2 of 2)
• Major component of cardiometabolic risk: development of
cardiovascular and metabolic disease
– Elevated LDL-cholesterol (≥ 130milligram/deciLiter)
– Inflammation
– Insulin resistance
– smoking
• Obesity associated with increased risk of premature
death

Figure 13.6

Obesity Is a Multifactorial Disease
• Variables include:
– Biology
– Physical activity environment
– Individual physical activity
– Individual psychology
– Societal influences
– Food environment
– Food consumption

Obesity Treatment: Diet and Exercise
• 500–1000 kilocalories/day deficit
• Increase physical activity gradually
• Exercise at least 30 minutes/day, 5 days/week
• Counseling and support groups
• Psychotherapy

Obesity Treatment: Medications
• Act as appetite suppressants and may increase satiety
• Physician involvement critical; many weight-loss drugs
have serious side effects
• Long-term safety of drugs being explored

Obesity Treatment: Supplements
• Dangerous or ineffective supplements can be marketed
and sold without meeting the FDA’s strict safety and
quality standards
• Insufficient evidence to support their use
• Stimulants speed up metabolic processes, are
controversial, and may be dangerous
– Caffeine, phenylpropanolamine (PPA), and ephedra

Obesity Treatment: Bariatric Surgery
• Considered a last resort for morbidly obese
• Surgery risks very high
• Surgery for morbid obesity
– Vertical banded gastroplasty
– Gastric bypass surgery
– Gastric banding
– Liposuction

Figure 13.8

Weight-Loss Diets (1 of 2)
• High-carbohydrate, moderate fat and protein diets
– Balanced in nutrients: 20–30% calories from fat,
55‒60% from carbohydrate, and 15–20% from
protein
– Weight Watchers, Jenny Craig, DASH diet, and the
USDA Food Guide
– Gradual weight loss (1–2 pounds per week)
– Typical energy deficits = 500–1,000 kilocalories per day

Weight-Loss Diets (2 of 2)
• Low-carbohydrate, high fat, and protein diets
– 55–65% of total energy intake as fat and remaining
energy from protein
– Dr. Atkins’ Diet Revolution, Sugar Busters!, and Paleo
Diet
– Cause ketosis, which will decrease blood glucose and
insulin levels and reduce appetite
– Concerns about long-term compliance, potential
health risks, and side effects

ABC News Video: Low-Carb Diet Trumps
Low-Far in Weight-Loss Study

ABC News Video: Coconut: How Healthy
Is the Superfood?

Achieve and Maintain Healthful
Weight (1 of 2)
• Set realistic and achievable goals that are:
– Specific
– Reasonable
– Measurable

Achieve and Maintain Healthful
Weight (2 of 2)
• Control portion sizes
• Frequently choose foods that are relatively low in energy
density
• Participate in regular physical activity
• Incorporate appropriate behavior modifications into daily
life
• Intuitive eating

ABC News Video: Experiment Shows
Portion Control is the Key to Healthy Eating

ABC News Video: Fast-Paced Movies,
Television Shows May Lead to More Snacking

Meal Focus Figure 13.9

Underweight
• As harmful as obesity
• Can be due to many factors
– Genetics
– Consuming too few Calories for exercise level
– Heavy smoking
– Underlying disease
– Anorexia nervosa

Safe and Effective Weight Gain
• Underweight: BMI of less than 2
18.5 kg/m
• Limit fat: <30% of total energy intake
• Eat 500 to 1,000 extra kilocalories/day
• Eat frequently throughout the day
• Avoid tobacco (depresses appetite and increases BMR)
• Exercise regularly with resistance training

Protein Supplements
• Include amino acid supplements, anabolic steroids, and
androstenedione
• Do not enhance muscle gain or result in improvements in
strength
• Cause major health problems: unhealthful changes in
blood cholesterol and mood disturbances

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