Human Nutrition 2310 Final Exam Study Guide Chapter 10 Energy Balance Weight Control and Eating Disorders Energy balance what it is different states what affects it o Energy Balance relationship between energy intake and energy expenditure Energy Equilibrium Positive Energy Balance Calories Consumed Calories Expended Calories Consumed Calories Expended Leads to growth weight gain recovery from illness or injury Weight gain not a natural part of aging stems from consuming more calories than expended as metabolic rate declines Negative Energy Balance Calories Consumed Calories Expended Leads to weight loss Loss of lean and adipose tissue Not desirable during growth stages of life cycle Components of energy expenditure and what influences these components o Energy Expenditure components Basal metabolism Physical activity Digestion absorption and processing of ingested nutrients Minor form of energy output Thermogenesis Size of each component shows relative contribution of that component to energy balance o Basal Metabolism Minimum amount of energy expended in fasting state 12 hours or more to keep a resting awake body alive in a warm quiet environment Women approximately 0 9 kcal kg hr Men approximately 1 0 kcal kg hr Accounts for 60 70 of total energy expenditure for a sedentary person Maintains activity of lungs heart liver brain kidneys etc BMR varies 25 30 among individuals Resting metabolism expressed as resting metabolic rate RMR Measured when person not fasting or completely rested 6 higher than BMR Factors that increase BMR Greater muscle mass Greatest influence on BMR Larger body surface area Male sex Men typically have more body surface area and muscle mass than women Body temperature Fever or cold environmental conditions Growth stages of life cycle Higher than normal secretions of thyroid hormones Key regulator of basal metabolism Aspects of nervous system activity e g stress hormone levels Caffeine and tobacco use Tobacco not recommended because of health risks Recent exercise Factors that decrease BMR Lower than normal secretions of thyroid hormones hypothyroidism Restricted calorie intake BMR declines 10 20 when calorie intake declines and body shifts to conserve weight Less body surface area and muscle mass Aging after age 30 years BMR drops 1 2 for each decade past 30 years due to lean body mass loss Can help maintain lean body mass and preserve BMR with physical activity o Physical activity Increases energy expenditure 25 40 above BMR Includes Physical activities e g climbing stairs rather than taking the elevator walking rather than driving to nearby store Exercise e g running swimming biking weightlifting Lack of physical activity is a contributing factor to obesity o Digestion absorption and processing of ingested nutrients Thermic effect of Food TEF Energy used to digest absorb transport store and metabolize nutrients consumed in diet Accounts for 5 10 of total energy expenditure varies slightly among individuals Food composition influences TEF Protein carbohydrate fat Large meal many small meals Thermogenesis o Adaptive Thermogenesis Heat produced when body expends energy for non voluntary physical activity Also known as Examples shivering when cold fidgeting maintaining muscle tone holding body up when not lying down Thermoregulation Non exercise activity thermogenesis NEAT Makes small contribution to overall energy expenditure Brown adipose tissue Specialized fat tissue that wastes energy as heat Adults have little brown adipose tissue role in adulthood unknown Mostly found in infants likely for thermoregulation and hibernating animals used to generate heat during cold months Calculation of estimated energy requirement EER o Estimated Energy Requirements EERs Developed by Food and Nutrition Board Formulas to estimate energy needs based on weight kg height m sex age years and physical activity level see table o Assessing EERs EER adult formulas Are estimates other factors e g genetics hormones can affect energy requirements Men 19 years and older Women 19 years and older EER 662 9 53 AGE PA 15 91 WT 539 6 HT EER 354 6 91 AGE PA 9 36 WT 726 HT Where EER Estimated Energy Requirement AGE Age in years PA Physical Activity Estimate from table WT Weight in kilograms lb 2 2 HT Height in meters in 39 4 What hunger appetite and satiety are o Hunger physiological drive to eat and find food Controlled by internal body mechanisms e g organs hormones hormone like factors nervous system o Appetite psychological drive to eat Affected mostly by external factors that encourage eating e g social customs time of day mood tastes sight o Satiety State in which there is no longer a desire to eat or a feeling of satisfaction that suppresses urge to eat for a period of time after a meal Regulated by hypothalamus Communicates with endocrine and nervous systems Integrates internal cues e g blood glucose levels hormone secretions sympathetic nervous system activity Damage to satiety center e g from cancer or surgery may lead to obesity or weight loss Factors that affect satiety Sensory and visual aspects of food e g food flavor and smell size and shape of portion served dietary variety Knowledge that a meal has been eaten Chewing Gastric distention i e stomach expansion Secretion of hormones during digestion Absorption and metabolism of nutrients Measurement of body composition methods used o Body Mass Index BMI Current standard weight for height Convenient to use cheap easier than measuring body fat Values apply to both men and women Calculation BMI Categories Underweight BMI 18 5 Healthy weight 18 5 24 9 Overweight 25 29 9 Obese 30 Health risks may begin at BMI 25 Provides an estimate of body fatness BMI 25 does not necessarily mean high body fat Categories may not apply to all populations Children Teens Older adults Muscular men athletes Pregnant and lactating women BMI should be used in combination with other measures to diagnose overweight or obesity o Estimating Healthy Weight Pounds per inch shortcut Women Men Start with 100 lb Add 5 lb for each inch of height above 5 feet Start with 106 lb Add 6 lb for each inch of height above 5 feet Weight estimate given 10 range o Measuring Body Fat Content Desirable body fat content Men 8 24 Women 21 35 require more fat for normal reproductive function Obese Men 24 body fat Women 35 body fat As body fatness rises above desirable levels health risks tend to increase For accurate body fat measurement requires body weight and body volume