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Transcript of Copyright © 2012 Pearson Education, Inc. 11 C H A P T E R Achieving and Maintaining a Healthful...
Copyright © 2012 Pearson Education, Inc.
11C H A P T E R
Achieving and Achieving and MaintainingMaintaining
a Healthful Body a Healthful Body WeightWeight
and In Depthand In Depth
© 2012 Pearson Education, Inc.
What Is a Healthful Body Weight?
A healthful weight 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
© 2012 Pearson Education, Inc.
What Is a Healthful Body Weight?
Underweight: having too little body fat to maintain health
Overweight: having a moderate amount of excess body fat
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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)
© 2012 Pearson Education, Inc.
BMI Chart
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BMI Classifications:
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Body Mass Variations
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Evaluating Body Weight
© 2012 Pearson Education, Inc.
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®
© 2012 Pearson Education, Inc.
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 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 energyoutput
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
© 2012 Pearson Education, Inc.
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
Leptin & Peptide YY or PYY: Reduces appetite Ghrelin: Increases appetite Brown adipose tissue Serotonin Cholecystokinin (CKK)
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Physiologic Factors
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
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
© 2012 Pearson Education, Inc.
Psychological and Social Factors
Psychosocial factors influencing our diet include 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 weight-loss, 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
• More than 29,000 weight-loss 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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
Fad Diets
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Weight Regain With Popular Diets
• 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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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
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
Obesity RatesPLAYPLAY
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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 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