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Because learning changes
everything.®7: Body Weight and
Body Composition
7: Body Weight and
Body CompositionYour Health Today, 9th Edition
Your Health Today, 9th Edition
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© McGraw Hill LLC
• Overweight and Obesity
Overweight: body weight that exceeds the
recommended guidelines for good health.
Obesity: body weight that greatly exceeds the
recommended guidelines.
No sex, age, state, racial group, or educational level is
spared from these problems, although they are worse
for the young and the poor.
Overweight and obesity are associated with serious
health problems.
•
© McGraw Hill LLC
• What Is a Healthy Body Weight?
There is no ideal body weight for each person, but
there are ranges for a healthy body weight.
Healthy body weight is defined as:
• Acceptable Body Mass Index (BMI).
• Body composition with an acceptable amount of body fat.
• Fat distribution that is not a risk factor for illness.
• Absence of any medical conditions that would suggest the
need for weight loss.
•
© McGraw Hill LLC
• Body Mass Index 1
Body mass index (BMI) is a measure of body weight in
relation to height (see Table 7.1 in the text).
• BMI = Weight in kilograms / (height in meters squared).
There appears to be a relationship between BMI and
risk of death, with the lowest risk in the 18.5 to 25
range.
• Underweight: BMI less than 18.5.
• Healthy weight: BMI between 18.5 and 24.9.
• Overweight: BMI between 25 and 29.9.
• Obese: BMI of 30 or greater.
•
© McGraw Hill LLC
• Body Mass Index 2
BMI may incorrectly estimate risk for some people.
• For those with muscular build, BMI may overestimate
body fat.
• For the elderly or others with low muscle mass, BMI may
underestimate body fat.
•
© McGraw Hill LLC
• Body Composition 1
The most common methods for body composition
assessment assess the ration of fat mass (FM) to
fat-free (or lean) mass (FFM).
• Assumption is that the FFM components of total body water,
protein, and bone mineral components have a fairly constant
relationship.
•
© McGraw Hill LLC
• Body Composition 2
Different groups have different body fat expectations.
• Healthy range for a typical male is 8 to 24%; male
athletes, 5 to 10%.
• Healthy range for a typical female is 21 to 35%; female
athletes, 15 to 20%.
• Below a certain body fat threshold, hormones cannot be
produced and health problems can occur.
One’s body fat percentage can be measured with
immersion (most accurate), X-ray, skinfold
measurement, and bioelectrical impedance.
•
© McGraw Hill LLC
• Body Fat Distribution
Where you carry your body fat is important in
determining your health risk.
• Large abdominal circumference is associated with high
cholesterol levels and higher risk for heart disease, stroke,
diabetes, and hypertension.
• Obese men tend to accumulate abdominal fat.
• Obese women tend to accumulate hip and thigh fat; however,
the onset of menopause shifts weight gain to the abdomen.
If your BMI is in the healthy range, a large waist may
signify an independent risk for disease.
•
© McGraw Hill LLC
• Issues Related to Obesity
Obese people are four times more likely to die before
their expected lifespan and have increased risk for:
• High blood pressure and elevated cholesterol.
• Diabetes.
• Coronary heart disease.
• Stroke.
• Gallbladder disease.
• Osteoarthritis.
• Sleep apnea.
• Lung problems.
• Certain cancers, such as uterine, prostate, and colorectal.
• For women, difficulty becoming pregnant and risk of complications.
•
© McGraw Hill LLC
• Diabetes and Obesity
The rates of obesity and diabetes in the U.S. have risen
in parallel.
About 90 to 95% of people with diabetes have Type 2,
the form strongly associated with obesity.
About 80% of American youth with Type 2 diabetes
are obese.
At any age group, small reductions in weight through
diet and exercise reduce the risk of developing diabetes.
•
© McGraw Hill LLC
• Discrimination and Obesity
Overweight children are often teased or bullied.
Weight-related bullying does not stop with adulthood.
• Those that are overweight face discrimination in hiring
practices, lower wages, and social stigma.
• One study found the overall, tangible cost of obesity for a
woman was $4,879 per year, and for a man, $2,646.
•
© McGraw Hill LLC
• The Problem of Underweight
Sudden, unintentional weight loss without a change in
diet or exercise level may signify an underlying illness
and should prompt a visit to a physician.
If you have difficulty keeping weight on, to gain weight
you need to change your energy balance.
• Eat more frequent and energy-dense meals.
• Add nutritional supplements as snacks.
• Reduce aerobic exercise and increase resistance or weight
training.
•
© McGraw Hill LLC
• What Factors Influence Your
Weight and Body Composition?
Many factors contribute—individual, social, and
environmental.
For most people, obesity is a multifactorial condition: a
person’s susceptibility is due to a complex interaction
among multiple genes and his or her environment.
•
© McGraw Hill LLC
• Genetic and Hormonal Influences 1
Your risk of becoming obese if both your parents are
obese is 80%.
Hundreds of genes have been associated with BMI
and obesity.
• In most cases, multiple genes may predispose toward obesity,
but interactions with the environment determine outcome.
Genetic affects on hormone levels result in alterations
in appetite or energy expenditure.
•
© McGraw Hill LLC
• Genetic and Hormonal Influences 2
Thyroid disorders can be associated with weight gain or
weight loss.
The thyroid gland controls much of your metabolic rate
through hormone production.
• When it is overactive, weight loss will likely result.
• When it is not active enough, weight gain will likely result.
•
© McGraw Hill LLC
• Genetic and Hormonal Influences 3
The stress response also affects eating patterns.
• Body releases several hormones, and in response, fat cells
release fatty acids and triglycerides and increase circulating
glucose.
• Chronic stress response increases the fat deposited in the
abdomen.
• Stress also affects eating patterns.
Researchers are also looking at the role of the gut
microbiome—the bacteria, viruses, and other
microorganisms of the stomach and intestines.
• Affect food digestion, absorption of nutrients, and metabolism.
•
© McGraw Hill LLC
• Age and Gender
Life stages affect body composition.
• One’s susceptibility for obesity is partially preprogrammed.
• Early-childhood physical activity and feeding patterns establish
biological programming and lifestyle habits.
• In adolescence, gender-specific patterns of fat distribution
emerge; and physical activity often decreases.
• The transition to college is also associated with weight gain.
• Weight gain is common during pregnancy.
• For most people, with aging comes a redistribution of body fat
toward the abdomen.
•
© McGraw Hill LLC
• Obesogenic Environments
and Lifestyle 1
Our chances of becoming obese are significantly
influenced by our environment.
Choice in food is driven by exposure, as well as cost
and convenience.
In general, unhealthy foods are more convenient and
less expensive than healthy foods.
Eating out has become a part of daily life.
• These foods tend to be higher in fat and calories and lower in
fiber than a home-cooked meal.
When confronted with large serving sizes, people eat
more and don’t realize it. •
© McGraw Hill LLC
• Figure 7.2 Visual images
of portion sizes.
Half a cup of fruit, vegetables, pasta, or rice is about the size of a small
fist. One cup of milk, yogurt, or chopped fresh greens is about the size of
a small hand holding a tennis ball. Three ounces of meat, poultry, or fish
is about the size of a computorer mouse a deck of cards. Two
tablespoons of salad dressing, oil, or butter is about the size of a ping
pong ball. One ounce of cheese is about the size of a pair of dice.
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((Closeup of right male hand): dinga/123RF; (Hand holding tennis ball): Pixtal/SuperStock; (Deck of cards): Hutchings
Photography/ Digital Light Source; (Golf ball): Photobvious/Getty Images; (Die): C Squared Studios/Getty Images)
•
© McGraw Hill LLC
• Obesogenic Environments
and Lifestyle 2
Our car-friendly, pedestrian-unfriendly communities
mean people are less likely to walk.
• Americans spend much of their leisure time on sedentary
entertainments like TV and the Internet.
Less sleep, not more, is associated with weight gain in
young adults.
If your friends gain weight, you are more likely to do so.
Weight cycling—repeated cycles of weight loss and
weight gain as a result of dieting—contributes.
•
© McGraw Hill LLC
• The Key to Weight Control:
Energy Balance
Energy balance: the relationship between caloric intake
(in the form of food) and caloric output (in the form of
metabolism and activity).
If you take in more calories than you use through
metabolism and movement (positive energy balance),
you store these extra calories as body fat.
If you take in fewer calories than you need (negative
energy balance), you draw on body fat stores to provide
energy.
•
© McGraw Hill LLC
• Estimating Your Daily
Energy Requirements 1
You can estimate your daily energy expenditure by
considering the:
• Thermic effect of food;
• Energy spent on basal metabolic rate; and
• Energy spent on physical activities.
•
© McGraw Hill LLC
• Estimating Your Daily
Energy Requirements 2
Thermic effect of food: an estimate of the energy
required to process the food.
• Estimated at 10% of energy intake.
Basal metabolic rate (BMR): rate at which the body
uses energy to maintain basic life functions, such as
digestion, respiration, and temperature regulation.
• About 60 to 70% of energy consumed.
•
© McGraw Hill LLC
• Estimating Your Daily
Energy Requirements 3
Nonexercise activity thermogenesis (NEAT): energy
expenditure related to work, daily living, or fidgeting.
• Varies tremendously, from 15% of daily energy expenditure in
sedentary people to as much as 50% in active people.
Exercise activity thermogenesis (EAT): typically ranging
from 15 to 30% of daily energy.
•
© McGraw Hill LLC
• Adjusting Your Caloric
Intake
A reasonable weight loss of 1 pound to 2 pounds per
week is a healthy goal.
• A pound of body fat stores 3,500 calories.
• To lose 1 pound in a week, you need to decrease your total
intake for the week by that 3,500 calories.
Faster weight loss tends to include loss of lean tissue
and a decrease in your basal metabolic rate.
Foods high in complex carbohydrates have a greater
thermic effect and take more energy to process than
high-fat foods.
•
© McGraw Hill LLC
• Weight-Loss Diets
Popular fad diets promote rapid change but are not
associated with long-term weight loss.
• Most follow a pattern of altering the balance of carbohydrates,
protein, and fat.
• Many label certain foods as “good” or “bad” or prescribe
certain “fat-burning foods.”
Most dietitians and physicians encourage more
balanced options and self-monitoring concepts.
•
© McGraw Hill LLC
• Weight Management
Organizations
Weight management organizations offer group support,
nutrition education, dietary advice, exercise counseling,
and other services.
• Weight Watchers and Jenny Craig: commercial programs.
• Take Off Pounds Sensibly (TOPS): a free program providing
group support; focuses on teaching.
• Overeaters Anonymous: a free program providing group
support; more suitable for binge eaters or others with
emotional issues related to weight.
•
© McGraw Hill LLC
• The Medical Approach 1
Very-low-calorie diets:
• Aggressive option that requires a physician’s supervision.
• Maintaining weigh loss is challenging.
Prescription drugs:
• Two types: those that act in brain to reduce food intake,
and those that act elsewhere in the body to reduce food
absorption.
• Side effects are an issue.
•
© McGraw Hill LLC
• The Medical Approach 2
Surgical options:
• Gastric surgery is never a first-line approach.
• Typical weight loss ranges from 20% to 30% of weight.
Nonprescription diet drugs and dietary supplements:
• Diet teas, bulking products, starch blockers, diet candies, sugar
blockers, benzocaine, etc.
• There are many safety concerns.
• Manufacturers of dietary supplements do not have to submit
proof of their efficacy or safety to the FDA.
•
© McGraw Hill LLC
• The Size-Acceptance Movement
The size-acceptance movement seeks to decrease
negative body image, encourage self-acceptance, and
end discrimination.
It emphasizes that people of any size can become more
fit and benefit from healthier food choices.
The goal is to find a balanced approach that combines
personal acceptance with promotion of a healthy body
composition.
•
© McGraw Hill LLC
• Achieving a Healthy Body
Composition: Tasks for Individuals 1
Emphasize components of a healthier lifestyle.
• Balanced diet emphasizing fruits, vegetables, and whole grains
in appropriate portion sizes.
• Weekly, 150 minutes of moderate-intensity or 75 minutes of
vigorous-intensity physical activity.
• Reduced time spent in sedentary activities.
• Target improvement in areas such as blood pressure,
cholesterol, and blood sugar level.
• Inclusion of peer support.
• Self-acceptance of body size.
• Follow-up evaluation by a health professional.
•
© McGraw Hill LLC
• Tasks for Individuals 2
Set SMART goals:
• Is the goal specific?
• Is the goal measurable?
• Is the goal attainable, through action on your part?
• Is the goal realistic, using small, gradual changes?
• Is the goal timely, in that you set a timeline for when you
will reach it?
•
© McGraw Hill LLC
• Tasks for Individuals 3
Choose an appropriate dietary approach, based on
specific goals.
• Lose or gain a small amount of weight.
• Maintain weight long-term.
• Replace unhealthy eating and exercise behaviors with more
healthy behaviors.
• Reduce risk or control symptoms of diabetes (including
maintainable short-term weight loss).
• Improve heart health.
•
© McGraw Hill LLC
• Table 7.2 Strategies for Changing Body Composition 1
Table divided into three columns
summarizes strategies for changing
body composition. The column headers
are marked from left to right as: Type,
theory, and examples.
Type Theory Examples
Balanced diets (for diabetes
and heart heath as well as
weight loss)
Encourage some restriction
of total calorie intake and
focus on lower
carbohydrates and lower
fats. They tend toward
balance among food groups.
DASH, Dr. Weil’s Anti-
inflammatory, flexitarian,
Jenny Craig, Mediterranean,
Mayo Clinic, traditional
Asian, Volumetrics, Weight
Watchers, Zone
Commercial diet programs Typically based on changing
food patterns and increasing
exercise, with the help of
behavioral counseling and
support systems.
Jenny Craig, Nutrisystem,
Weight Watchers
Low-calorie diets (includes
most weight-management
organizations)
Specifically incorporate
reduction in overall calorie
intake.
Body Reset, HMR, Jenny
Craig, Nutrisystem, raw food,
Weight Watchers
•
© McGraw Hill LLC
• Table 7.2 Strategies for Changing Body Composition 2
Table divided into three columns
summarizes strategies for changing
body composition. The column headers
are marked from left to right as: Type,
theory, and examples.
Type Theory Examples
Food-group-restrictive diets Certain types of food
classified as “bad” are
eliminated; other foods are
“good” metabolic
promoters.
Low-fat: macrobiotic, Ornish,
TLC, vegetarian, vegan.
Low-carb/high-protein:
Atkins, Paleo, South Beach.
Detox: Master Cleanse (aka
Lemonade Diet).
Meal replacements (shakes
and bars)
Prepacked bars and drinks
are used to control calorie
intake.
Body Reset, HMR, Medifast,
Slim-Fast
Prepackaged meals Purchased meals are used to
control calorie intake.
HMR, Jenny Craig,
Nutrisystem, Weight
Watchers
•
© McGraw Hill LLC
• Tasks for Individuals 4
Evaluate the support and obstacles in your
environment, asking yourself if your change in diet is:
• Realistic;
• Moderate and flexible;
• Safe;
• Holistic, incorporating regular exercise;
• Compatible with your relationships;
• Affordable; and
• Research based.
•
© McGraw Hill LLC
• Tasks for Individuals 5
Use tools to help change your patterns.
• Stimulus control: identify environmental cues associated
with unhealthy eating habits.
• Self-supervision: keep a log of the food you eat and the
physical activity you do.
• Social support and positive reinforcement: recruit others
to join you in your healthier habits.
• Stress management: use healthy techniques and
problem-solving strategies to handle stress.
• Cognitive restructuring: moderate any self-defeating thoughts
and emotions; redefine your body image by thinking about
what your body can do.
•
© McGraw Hill LLC
• Tasks for Society
Changes in social policies are also needed to combat the
obesity epidemic.
Promote healthy foods, lowering the price of low-fat,
nutritious food to increase the rates at which people
choose them.
Support active lifestyles through community planning
Support consumer awareness about healthy eating choices.
• If consumers don’t buy the products depicted in ads, or if they
complain about the content of ads, food manufacturers will
eventually respond.
Encourage health insurers to cover obesity prevention
programs.
•
© McGraw Hill LLC
• In Review
• How is healthy body composition defined?
• What factors influence weight?
• What is the best way to manage body weight?
• Are there quick fixes for overweight and obesity?
• How can individuals and society promote healthy
weight throughout life?
•
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