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



Underweight: having too little body fat to maintain health

Overweight: having a moderate amount of excess body fat



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


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



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)


BMI Chart


BMI Classifications:


Body Mass Variations



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®



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


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


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


Energy Balance


Components of Energy Expenditure


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


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


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


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


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


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


Factors Affecting Basal Metabolic Rate


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


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


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)


Physiologic Factors

Blood glucose levels Stomach expansion Nutrient absorption from the small intestine Beta-endorphins Neuropeptide Y


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


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


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


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


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


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


The Business of Weight Loss

• More than 29,000 weight-loss products and services are available

• Almost none of them work


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


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


Fad Diets


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


Achieve and Maintain Healthful Weight

Healthful weight change requires Gradual change in energy intake Regular and appropriate physical exercise Application of behavior modification techniques



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



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


Weight-Loss Strategies

Guidelines for successful weight loss

1. Set realistic goals Specific Reasonable Measurable

Monitor progress regularly


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


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


Successful Weight Loss


Gradual Weight Loss


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


Food is medicine



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


In Depth: Obesity

Chronic diseases linked to obesity include

Hypertension High cholesterol, triglycerides, and LDL-cholesterol Type-2 diabetes Heart disease


In Depth: Obesity

Chronic diseases linked to obesity include

Stroke Gallbladder disease Certain cancers Depression Cognitive decline

Obesity RatesPLAYPLAY


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


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


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


In Depth: Obesity


ABC News Nutrition Video

Diet Dream Drug: Hope or Hype: Pros and Cons of Alli



Can You Be Slim and Obese? Hidden Risk of Normal Weight Obesity



Calorie Count: Eat by the Numbers



Low-Cost, High-Impact Solutions

copyright © 2012 pearson education, inc. 11 c h a p t e r achieving and maintaining a healthful...

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