Download Achieving and Maintaining a Healthy Body Weight

Achieving and Maintaining
a Healthy Body Weight
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
13
NHANES Data
National Health And Nutrition Examination Survey, 1999-2002
•Indicated an estimated 65% of US adults are
either overweight or obese
•
This represents a prevalence that is 16% higher
than estimates from NHANES, 1988-94
•16% of children 9-16 yoa (~9 million) are
overweight
•
This is triple the amount from 1980 estimates
www.cdc.gov/nchs/products/pubs/pubd/hestats/obese/obse99.htm
www.cdc.gov/nchs/products/pubs/pubd/hestats/obese/obse99.htm
www.cdc.gov/nchs/products/pubs/pubd/hestats/obese/obse99.htm
Obesity: Cause for Concern
•Overweight & obesity results from a complex
interaction between genes and the environment
characterized by long-term energy imbalance
•Major public health challenge as a major
contributor to preventive death in the US
Copyright © 1998 NIH Publication No. 98-4083
Obesity
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Figure 13.10
Disorders Related to Energy Intake
Overweight and obesity – epidemic in US linked
to many chronic diseases:
 Hypertension
 Dyslipidemia
- elevated total cholesterol,
triglycerides, and LDL cholesterol, and
decreased HDL cholesterol
 Type 2 diabetes
 Heart disease and stroke
 Gallbladder disease
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Disorders Related to Energy Intake
Overweight and Obesity – epidemic in US linked to
many chronic diseases:





Osteoarthritis
Sleep apnea
Certain cancers: colon, breast, endometrial, and
gallbladder
Gestational diabetes, premature fetal deaths, neural tube
defects, and complications during labor and delivery
Depression
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Why treat obesity?
•Condition substantially raises risk of morbidity
and mortality
•Evidence from controlled trials indicates that
weight loss reduces risk factors for disease
•Estimated that at any given time 30-40% of
population are trying to lose weight
•
An estimated $30-40 billion is spent on diet
products and self-help books yearly
Copyright © 1998 NIH Publication No. 98-4083
What is a Healthful Body Weight?
A healthful weight
 Is
appropriate for your age and physical
development
 Is maintained without constant dieting
 Is based on family history of body shape and
weight
 Promotes good eating habits and allows for
regular physical activity
 Is acceptable to you
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
What is a Healthful Body Weight?
Underweight: having too little body fat to
maintain health (BMI < 18.5 kg/m^2)
Overweight: having a moderate amount of excess
body fat (BMI 25-29.9 kg/m^2)
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
What is a Healthful Body Weight?
Obese: having an excess of body fat that
adversely affects health (BMI 30-39.9 kg/m^2)
Morbid obesity: body weight exceeding 100% of
normal, creating a very high risk for serious
health consequences (BMI > 40 kg/m^2)
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
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
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Evaluating Body Weight
Body Mass Index
 Expresses
the ratio of a person’s weight to the
square of their height
 BMI = weight (kg) / height (m)2
 BMI = [weight (lbs) / height (inches)2] X 703
 BMI values below 18.5 or above 30 have
increased health risks
 Correlates
with both morbidity & mortality
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Evaluating Body Weight
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.1
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.2
Evaluating Body Weight
Body composition
 Measure
of body fat and lean body mass
 Can be measured by






Underwater weighing
Skinfold measurements
Bioelectric impedance analysis
Near infrared reactance
Dual-Energy X-Ray Absorptiometry
Bod Pod™
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Evaluating Body Weight
Fat distribution pattern
 Apple-shaped
fat patterning – upper body

Increased risk for chronic diseases
 Men tend to store fat in their abdominal region
 Pear-shaped
fat patterning – lower body

No significant increased risk for chronic diseases
 Women tend to store fat in their lower body
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.3
Evaluating Body Weight
Fat distribution pattern:
 Abdominal
fat increases chronic disease risk
 Waist-to-hip ratio
Men’s waist-to-hip ratio is higher than 0.90
 Women’s is higher than 0.80

 Waist
circumference

Men above 40 in. (or 102 cm.)
 Woman above 35 in. (or 88 cm.)
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.4
Evaluating Body Weight
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Table 13.3
Gaining or Losing Weight
Whether a person gains or loses weight depends
on
 Energy
intake vs. energy expenditure
 Genetic factors
 Childhood weight
 Behavioral factors
 Social factors
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Energy Balance
Energy balance
 Occurs
when energy intake = energy
expenditure
 Energy intake is kcal from food
 Energy expenditure is energy expended at rest
and during physical activity
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.5
Energy Intake
When total daily energy intake exceeds the
amount of energy they expend, weight gain
results
An excess intake of approximately 3,500 kcal
will result in a gain of one pound
 Without
exercise, this gain will likely be fat
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Energy Expenditure
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
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.6
Energy Expenditure
Direct calorimetry is a
method that measures the
amount of heat the body
releases
Indirect calorimetry
estimates energy
expenditure by measuring
oxygen consumption and
carbon dioxide production
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Energy Expenditure
Basal Metabolic Rate (BMR)
 Energy
expended to maintain basal, or resting,
functions of the body
 The highest proportion of total energy
expenditure (60-70%)
 BMR increases with more lean body mass,
during stress, and periods of growth
 BMR decreases with age and during energy
restriction
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.8
Energy Expenditure
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Table 13.4
Energy Expenditure
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
20-35% of someone’s total energy
output each day
 About
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Genetic Factors
About 25% of one’s body
fat is accounted for by
genetic influences
Different ideas have been
suggested to explain the
impact of genetics on body
fat


Thrifty Gene Theory
Set-point Theory
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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
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
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 their set
point
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Childhood Factors
Environmental factors in childhood can influence
 Food
choices
 Activity levels
 Later adult behaviors
Childhood overweight increases the risk of heart
disease and premature death as an adult
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.11
Composition of the Diet
Theory states that overeating dietary fat promotes
storage as adipose tissue
Overeating carbohydrate or protein will also lead
to weight gain
 Important
to maintain a balanced diet
combining fat, carbohydrate, and protein
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Physiologic Factors
Hunger vs. appetite
Proteins affect the regulation of hunger and
storage of body fat
 Leptin
acts to reduce food intake (feeling of satiety)
 Ghrelin stimulates food intake
 Peptide YY (PYY) decreases appetite
 Uncoupling proteins in brown adipose tissue
increase energy expenditure
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Physiologic Factors
Increase satiety (or decrease food intake)
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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
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Social Factors
Social factors influencing our diet include:
 Family
or cultural traditions
 Holidays and celebrations
 Easy access to high-fat foods
 Less physically active lifestyles
 Societal expectations of the “perfect” body
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Achieve & Maintain Healthful Weight
Healthful weight change requires
 Gradual
change in energy intake
 Regular and appropriate physical exercise
 Application of behavior modification
techniques
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Set appropriate and realistic goals
•Initial goal of weight loss therapy is to reduce
body weight by ~10% from baseline in 6 months
of therapy
•Depending on the amount of overweight/obesity
a decrease of 500-1000 kcal/day will lead to
weight losses of ~1-2 pounds/week
Copyright © 1998 NIH Publication No 98-4083
Set appropriate and realistic goals
•After 6 months, the rate of weight loss usually
declines and weight plateaus (changing resting
metabolic rates & difficulty adhering to lifestyle)
•Experience reveals that lost weight usually will
be regained unless a weight maintenance
program consisting of diet therapy, physical
activity, and behavior therapy is continued
indefinitely
Copyright © 1998 NIH Publication No. 98-4083
Weight Loss Diets
High-fat, low-carbohydrate, high-protein diets
 Cause
ketosis, which will decrease blood
glucose and insulin levels and reduce appetite
 Dr. Atkins’ Diet Revolution, Protein Power
 Nutritionally inadequate, require supplements
 Side effects: constipation, diarrhea, nausea,
headaches, ketone breath, insomnia, fatigue
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Weight Loss Diets
Moderate-fat, high-carbohydrate, moderateprotein diets
 Balanced
in nutrients: 20-30% calories from
fat, 55-60% carbohydrate, 15-20% protein
 Weight Watchers, Jenny Craig, DASH diet, and
the USDA MyPyramid
 Gradual weight loss (1-2 pounds per week)
 Typical energy deficits 500-1000 kcal per day
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Weight Loss Diets
Low-fat and very-low-fat diets
 About
11-19% of total energy as fat, while
very-low-fat-diets contain less than 10%
 Dr. Dean Ornish’s Program for Reversing Heart
Disease and The New Pritikin Program
 Emphasize complex carbohydrates and fiber
 Regular physical activity is a key component
 Lower LDL cholesterol, triglyceride, glucose,
insulin levels, and blood pressure
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Achieve & Maintain Healthful Weight
Safe and effective weight loss
 Follow
recommended serving sizes
 Reduce high-fat and high-energy food intake
 Regular physical exercise: increase energy
expenditure and BMR
 Start
slow & increase gradually
 Long-term goal: accumulate at least 30 minutes of
moderate intensity activity on most, and
preferably all, days of the week
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Achieve & Maintain Healthful Weight
Weight loss medications:
 Many
have been removed from market
 Should never be used without lifestyle
modifications
Herbal supplements:
 Not
FDA regulated
 Recent “nationwide alert” of tainted weight loss
supplements
 Can pose very serious health risks
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
What do “successful losers” have in common
•The National Weight Control Registry
•People volunteered to participate in study if
they met criteria of maintenance of at least 30 lb
weight loss for at least one year (4000
participants)
•Commonly shared features:
•
•
•
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Ate a low-fat, high-carbohydrate diet
Ate breakfast almost every day
Frequent self-monitoring of weight
Had high level of physical activity (~60-90 min mod-intensity
activity every day)
Bariatric Surgery
•May be advisable in those with BMI > 40, or for
those with BMI > 35 with other comorbidities,
whose efforts at other therapies have failed
•
Vertical banded gastroplasty
• Gastric bypass
• Gastric banding
•Compared to other interventions, surgery has
produced the longest period of sustained weight
loss
Copyright © 1998 NIH Publication No. 98-4083
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.12
Achieve & Maintain Healthful Weight
Effective weight gain:
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Eat 500 to 1,000 extra kcal/day
Eat frequently throughout the day
Maintain a balanced diet
Eat a diet that contains 55% of total energy from
carbohydrate; 25-35% of total energy from fat; and 1020% of total energy from protein
Avoid tobacco (depress appetite and increase BMR)
Exercise regularly with resistance training
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings