1 Energy Balance and Healthy Body Weight
2 Trends with Body WeightIn the U.S. Obesity is an escalating epidemic In the year 2000 64% of U.S. adults were overweight 30% were obese One of every seven U.S. children and teenagers is overweight 300,000 people in the U.S. die each year from obesity-related diseases 70+% of obese people suffer from at least one other major health problem ≈50% of hypertension cases are due to excess weight
3
4 Risks of Underweight StatusUnderweight people are at greater risk when Fighting a wasting disease People with cancer often die from starvation Hospitalized if they have to go without food for days at a time when undergoing tests for surgery Underweight people should gain body fat as an energy reserve acquire reserves of nutrients that can be stored
5 Risks of Overweight StatusTwo types of adiposity: Central (Apple): Fat around the chest and abdomen Subcutaneous (Pear): fat around the hips & thighs
6 Risks of Overweight StatusCentral Obesity (visceral fat) Increases the risk of Diabetes Stroke Hypertension Coronary artery disease Influencing factors Gender Menopause Smoking Alcohol Physical in activity
7 Measuring BMI BMI (body mass index) weight for heightOften correlates with degree of body fatness and disease risk Calculated as wt (kg)/ht2(m) Body Mass Index (BMI) Correlates with body fatness Used to evaluate health risks
8 Measuring BMI BMI values fail to distinguish between how much of a person’s weight is fat and where the fat is located Do not use with Athletes Pregnant and lactating women Adults over 65 Young Children
9 Measuring “Fatness” Body composition Measures: AnthropometryProportion of muscle, bone, fat Measures: Anthropometry Fat fold tests Underwater weighing Bioelectrical impedance Dual energy X-ray absorptiometry (DEXA) Waist circumference (men>40; women>35)
10 How Many Calories? Energy output Basal metabolism Voluntary activitiesEnergy output Basal metabolism Sum total of energy expended on all of the involuntary activities needed to sustain life Excludes digestion Voluntary activities Thermic effect of food 5%-10% of a meal’s energy is expended in stepped-up metabolism in the 5+ hours after a meal
11 How to Calculate Your EER© 2006 Thomson-Wadsworth
12 The Mystery of Obesity Factors that correlate with obesityBirth order Number of brothers Divorced/single parents Nonprofessional parents Unemployed parents Early menstruation Ethnicity More factors that correlate with obesity Exposure to a variety of foods Fast-food consumption Fat, protein, carbohydrate intake Increased wealth Less leisure time International travel Geographic location
13 The Mystery of Obesity More factors that correlate with obesityLower education level Lower social class Maternal famine Obesity during gestation Meal skipping Meals eaten away from home Napping habits Sleep deprivation Reduced alcohol intake Increased alcohol intake Sedentary behavior Television watching Substandard housing
14 Why Did I Eat That? Hunger Other factors influencing hungerSensation that signals a need for food Occurs roughly 4-6 hours after eating After the food has left the stomach and much of the nutrient mixture has been absorbed Triggered by a contracting empty stomach, an empty small intestine, the stomach hormone ghrelin produced between meals, and chemical and nervous signals in the brain Other factors influencing hunger Nutrients in the blood stream Size and composition of the previous meal Weather Exercise Sex hormones Illnesses
15
16 Why Did I Eat That? Appetite Other factors affecting appetiteThe psychological desire to eat Can be experienced without hunger The sight and smell of food can stimulate the brain’s endorphins, molecules that create an appetite despite an already full stomach Illness or stress may result in the loss of appetite in a person in physical need of food Other factors affecting appetite Hormones Inborn appetites Learned preferences, aversions, timings Customary eating habits Social interactions Some disease states Appetite stimulants, depressants, mood-altering drugs Environmental conditions
17 Why Did I Eat That? Satiety SatiationThe perception of fullness that lingers after a meal Suppresses hunger Associated with High-fiber foods Water Foods that have been puffed up from air Satiation The perception of fullness that builds throughout a meal Stomach stretching to accommodate a meal triggers receptors in the stomach to send signals to the brain that tell it that the stomach is full The brain also detects nutrients in the blood
18 Why Did I Eat That? Leptin: A Satiety HormoneLeptin: A Satiety Hormone Appetite-suppressing hormone Produced by adipose tissue Directly linked to appetite and body fatness Gain of body fat stimulates leptin production Reducing food consumption; resulting in fat loss Loss of body fat reduces leptin secretion Increasing appetite
19 Inside-the-Body Causes of ObesityChildren with at least one obese parent have a 40%-70% chance of becoming obese While genetics influences a person’s tendency to become obese, lifestyle choices determine if the tendency is realized The search for obesity treatments through genetic research has been disappointing People can override signals of satiety and hunger People seek ease and as a result decrease their energy expended in activities required for daily living
20 Outside-the-Body Causes of ObesityExternal Cues to Overeating Variety influences animals, including humans, to eat even when they are not hungry Delectable foods, such as sweets, snacks, etc. Overeating also occurs in response to Loneliness Yearning Craving Addiction Compulsion Depression Time of day Stress
21 Outside-the-Body Causes of ObesityFood Price, Availability, and Advertising High-calorie fast foods are relatively inexpensive, widely available, heavily advertised Physical Inactivity Some people are obese not because of how much they eat, but because they move too little Diet histories of obese people often report energy intakes similar to, or even less then, those of others It is the lack of physical activity that results in an energy surplus
22 Weight Gain & Weight LossThe balance between energy intake and energy output determines whether you gain, lose, or maintain body fat A slight change in body weight may not indicate a change in body fat body fluid content, bone minerals, muscles, bladder or digestive tract contents Change often correlates with time of day Change can be due to water gain or loss
23 Weight Gain & Weight LossModerate Weight Loss v. Rapid Weight Loss The normal between-meal interval is 4-6 waking hours; hours at night About the length of time it takes people to use up most of the readily available fuel When energy input is
24 Weight Gain & Weight LossWeight loss takes time and patience Even modest weight loss, even for a person still overweight, can improve health © 2006 Thomson-Wadsworth
25
26 Low Carbohydrate DietsResponse to a Low-Carbohydrate Diet Low-carbohydrate diets bring about responses similar to those seen when fasting As carbohydrate runs low the body breaks down fat and protein for energy and ketones form to feed the brain To prevent this the DRI for carbohydrates is set at 130 grams/day; 45%-65% of total energy intake is recommended for health
27 Low Carbohydrate DietsLow-carbohydrate, high-protein diets bring about large initial weight losses This large initial weight loss is primarily the water and glycogen losses that occur when carbohydrate is lacking This kind of weight loss rapidly reverses when a person begins eating normally Loss of appetite accompanies any low-calorie diet
28 Best Strategies for weight lossDietary Guidelines for Americans 2005 Energy in must be less than energy expended Calorie intake must decrease to attain weight loss Diet based on all the food groups may be the safest and easiest in the long term While providing adequate essential nutrients and limiting saturated and trans fat intake Increase physical activity
29 Best Strategies for weight lossFDA plan to deal with the obesity epidemic Require food labels to prominently display calorie counts and to use meaningful serving sizes Launch a “Calories Count” consumer education program Ensure greater accuracy of food label nutrient data Accelerate development of obesity drugs
30 Best Strategies for weight lossSetting Goals For an overweight person First reasonable goal may be to prevent weight gain; then Reduce body weight by 5%-10% over the course of a year Recognize that maintenance is often more difficult than weight loss
31 Best Strategies for Weight LossOnce overall goals have been set Set smaller goals for diet, physical activity, and behavioral changes Slow weight loss is less likely to result in a rapid regain of weight than is rapid weight loss Rapid weight loss and excessive fat restriction can cause gallstones or dangerous electrolyte imbalances
32 Best Strategies for Weight LossChoosing Realistic Calorie Intakes Energy intakes lower than about 800 calories are unsuccessful at achieving lasting weight loss, lack necessary nutrients Balancing Carbohydrates, Fats, and Protein Diets for weight management should provide carbohydrates, protein, fat within the DRI recommended ranges Carbohydrate: 45% - 65% of total calorie intake Fat: 20% - 35% of total calorie intake Protein: 10% - 35% of total calorie intake
33 Best Strategies for Weight LossHigh-fiber, unprocessed or lightly processed foods offer bulk and satiety for fewer calories than quickly consumed refined foods Choose whole grains Avoid refined grains, added fats, and sugars Choose fats sensibly Avoid saturated and trans fats Include enough of the health Protein Choose lean meats or other low-fat protein sources
34 Best Strategies for Weight LossAlcohol Limit intake Provides calories but no nutrients Alcohol reduces inhibitions and can sabotage a diet Portion Sizes Restaurant meals are problematic Use a measuring cup to learn to judge portion sizes Meal Spacing Eat breakfast Eating breakfast may reduce food intake all day long People who skip breakfast are more likely to be overweight
35 Best Strategies for Weight LossEnergy density : energy provided by a food relative to its weight To lower caloric intake, reduce the energy density
36 Physical Activity for Weight LossUSDA Recommendation of ≈ minutes of moderate physical activity per day to prevent weight gain and support weight loss Diet, in combination with exercise, promotes fat loss, promotes muscle retention, inhibits weight gain Exercise helps people follow diet plans more closely
37 Low Carbohydrate DietsGreater initial weight loss on high-protein diet may be due to Water and glycogen loss People on low-carbohydrate diets consuming fewer calories Most people who lose a substantial amount of weight and keep it off do so on low-fat, high- carbohydrate diets
38 Low Carbohydrate DietsHigh Protein and Animal Fat Intakes High in saturated fat Increased cardiovascular disease risk Increased risk of breast cancer Low Carbohydrate Intake Mixed results with regard to cardiovascular risk Correlates with lean body composition and good health Contain important nutrients that would otherwise be missing from the diet Chronic ketosis
39 Surgery to Treat ObesityExtreme obesity (BMI≥40; BMI≥35 with coexisting disease); a.k.a. morbid obesity Health permitting, surgery may be an option Surgical reduction of stomach size Surgery is not a cure for obesity Some do not lose the expected pounds Some who initially lose weight gain it back through the course of time
40 © 2006 Thomson-Wadsworth
41 Surgery to Treat ObesityLong-term safety and effectiveness of gastric surgery primarily depends on compliance with dietary instructions Complications immediately following surgery include Infections Nausea Vomiting Dehydration Long-term complications include Vitamin and mineral deficiencies Psychological problems Such surgery requires lifelong medical supervision
42 Surgery to Treat ObesityLipectomy (liposuction) Cosmetic procedure If fat is gained back after surgery, as it often is, a lumpy, dimpled layer can be formed There can be serious complications, including death, as a result of the surgery
43 Maintaining New Body WeightA reason why gimmicks fail is that they fail to produce lasting changes Disappointment, frustration, and self- condemnation are common in dieters who have returned to their original weight or even gained weight A key to weight maintenance is accepting it as a lifelong endeavor Prepare the mind for making permanent changes More physically active than the average person Monitor fat grams, calorie intake, and body weight
44 Maintaining New Body WeightEat a high-fiber (high-carbohydrate), lower- fat, higher in fruits and vegetables diet Consume sufficient water each day Cultivate and honor realistic expectations regarding body size and shape Exercise Without exercising, one can develop a history of weight cycling Which may damage health by weakening the immune response
45 Eating Disorders Causes of eating disorders≈5m people in the U.S. have eating disorders Anorexia nervosa Bulimia nervosa Many more suffer from binge eating disorder ≈85% start during adolescence Markers of disordered eating including restrained eating, binge eating, purging, fear of fatness, distorted body image are common Causes of eating disorders Excessive pressure to be thin Painful emotions may be turned inward by youngsters to express dissatisfaction with body
46 Eating Disorders Eating Disorders in SocietyEating disorders have many causes Sociocultural Known only in developed nations Become more prevalent as wealth increases and food becomes plentiful Psychological Heredity Probably neurochemical Society sets unrealistic ideals for body weight Especially for women
47 Eating Disorders Eating Disorders in AthletesAthletes and dancers are at special risk of eating disorders Female athlete triad Disordered eating Amenorrhea Osteoporosis Males: disordered eating brings on many of the same physical problems affecting female counterparts
48 Eating Disorders The Female Athlete TriadFemale athletes often compare themselves to unsuitable weight standards An ultra-slim appearance has long been considered desirable in activities such as dancing, gymnastics, and figure skating
49 Anorexia Nervosa No one knows what causes anorexia nervosaSelf-Starvation Most anorexia nervosa victims come from middle- or upper-class families Males are≈ 5% to 10% of cases Incidence among male athletes & dancers may be higher No one knows what causes anorexia nervosa Central to its diagnosis is a distorted body image that overestimates body fatness Anorexics may be perfectionists
50 Anorexia Nervosa: ResultsPhysical Perils Protein-energy malnutrition Body tissues are depleted of needed fat and protein Growth ceases and normal development falters The brain loses significant amounts of tissue Nerves function abnormally Electrical activity of the brain becomes abnormal Insomnia Digestive functioning becomes sluggish The stomach empties slowly The lining of the intestinal tract shrinks The digestive tract fails to digest food adequately, Production of digestive enzymes slows Diarrhea
51 Anorexia Nervosa Anemia Impaired immune response Altered blood lipidsHigh blood concentrations of vitamins A & E Low blood proteins Dry skin Low body temperature The development of fine body hair
52 Anorexia Nervousa Treatment of Anorexia NervosaRequires a multidisciplinary approach Approaches relating to food and weight Appropriate diet is crucial for normalizing weight Approaches concerned with relationships with oneself and others Clients are classified based risk & malnutrition
53 Bulimia Nervosa CharacteristicsMuch more prevalent then anorexia nervosa True incidence is difficult to establish People often suffer in secret and may deny the existence of a problem More men suffer from bulimia nervosa than from anorexia nervosa However, bulimia nervosa is still most common in women
54 Bulimia Nervosa Bulimia Nervosa: Binge Eating and PurgingFood is not consumed for its nutritional value During a binge, eating is accelerated by hunger from previous caloric restriction During a binge, nearly 1,000 extra calories are consumed, but could be MUCH more There may be several binges in a day Typical binge foods Easy-to-eat foods Low-fiber Smooth-texture High-fat High-carbohydrate
55 Bulimia Nervosa After a binge a cathartic or emetic may be usedConsequences of Vomiting Hands may be scraped raw against the teeth Swollen neck glands and reddened eyes from straining to vomit Bloating, fatigue, headache, nausea, pain Irritation and infection of the pharynx, esophagus, salivary glands Erosion of the teeth and dental caries The esophagus or stomach may rupture or tear
56 Binge Eating Disorder Binge Eating DisorderUp to 50% of all people who restrict eating to lose weight periodically binge without purging Including about 1/3 of obese people who regularly engage in binge eating Obesity itself does not constitute an eating disorder