ENERGY BALANCE, WEIGHT CONTROL AND EATING DISORDERS PART 1 OF 2 C H A P T E R 1 0

Transcription

1 ENERGY BALANCE, WEIGHT CONTROL AND EATING DISORDERS PART 1 OF 2 C H A P T E R 1 0

2 LEARNING OUTCOMES Describe the many factors that have resulted in an increase in obesity in the US What is energy balance and what are the components of energy balance? Know the methods used to measure energy expenditure by the body. Explain internal and external regulation of hunger, appetite and satiety. Describe the methods available to measure body composition. What tools are available to determine whether body weight and body composition are healthy? Discuss the impact of genetics and environment on body weight and composition. 2

3 Obesity Trends* Among U.S. Adults BRFSS, 1990, 2000, 2010 (*BMI 30, or about 30 lbs. overweight for 5 4 person) html 3

4 OBESITY 4

5 The prevalence of childhood obesity is also increasing Growth in Childhood Obesity Over Three Decades Age 6 to 11: 4% 13% Age 12 to 19: 5% 14% If obese at age 6 50% chance of lifelong obesity If obese at age 13 75% chance of lifelong obesity Blacks Mexican Americans 50% more likely to be obese than whites 5 From NHANES

6 HOW DID WE GET FROM A PREVALENCE OF 45% TO 65%? 6

7 ENERGY BALANCE Energy intake Energy expenditure 7

8 ENERGY BALANCE Energy equilibrium Energy intake equals energy expenditure Positive energy balance Energy intake greater than energy expenditure Negative energy balance Energy intake less than energy expenditure 8

9 FACTORS AFFECTING ENERGY BALANCE AND WEIGHT Role of environment Role of developmental behaviors Role of genetics Identical twins Set point theory Genetic and environment synergy Diseases and disorders 9

10 OBESITY: A MULTIFACTORIAL DISORDER Genetics Development Behaviors/likes, etc. hard wired in Environment 10

11 ENERGY INTAKE Energy intake Estimated via nutrient databases Calories based on bomb calorimeter Fat 9 kcal/gm Carbohydrates 4 kcal/gm Protein 4 kcal/gm Alcohol 7 kcal/gm 11 11

12 DECREASE YOUR ENERGY INTAKE TO LOSE WEIGHT Daily calories to maintain a weight of 300 pounds 2600 kcal/day To lose 1-2 pounds/week, you need to deficit 3500 kcal/pound For 1 lb: 3500 kcal/7 days = -500 kcal/day For 2 lbs: 7000 kcal/7 days kcal/day Daily calories to lose 1 pound/week 2100 kcal/day Daily calories to lose 2 pounds/week 1600 kcal/day 12

13 WHY IS REDUCING KCAL SO HARD? Out of Control Environment Stress and busy schedules Skipped meals Calorie-dense foods Large portions Increased variety 13

14 CONTRIBUTIONS TO OBESITY: LEARNED BEHAVIORS Learned Behaviors Clean your Plate Club Food as a coping mechanism Food for celebration Food is love Food as a reward Food as comfort 14

15 CHICKEN CAESAR SALAD 20 Years Ago Today 390 calories 1 ½ cups 790 calories 3 ½ cups Calorie Difference: 400 calories 15

16 If you walk the dog for 1 hour and 20 minutes, you will burn approximately 400 calories.* *Based on 160-pound person 16

17 It is easy to avoid expending energy Energy expenditure 17

18 ENERGY EXPENDITURE Basal metabolic rate (BMR) Minimum amount of energy in a fasting state Factors that increase basal metabolism Factors that decrease basal metabolism Other factors that go into TOTAL energy expenditure: Physical activity Thermic effect of food Adaptive thermogenesis 18

19 MEASURING ENERGY EXPENDITURE Direct calorimetry Measures body heat in a sealed enviorment Indirect calorimetry Collecting expired air Stable isotopes Estimated energy requirements (EERs) Harris-Benedict equation 19

20 EQUATIONS USED TO ESTIMATE ENERGY NEEDS Harris Benedict Women: = ( 4.35 x weight in pounds ) + ( 4.7 x height in inches ) - ( 4.7 x age in years ) Men: = 66 + ( 6.23 x weight in pounds ) + ( 12.7 x height in inches ) - ( 6.8 x age in year ) EER: Similar but has physical activity built in to the equation Also, has separate equations for adult men and women, toddlers, boys and girls aged 3-18, and obese girls and boys aged

21 PHYSICAL ACTIVITY 21

22 INCREASE YOUR ENERGY EXPENDITURE TO LOSE WEIGHT To lose 1-2 pounds/week via exercise, you need to burn kcal in a week You burn about 100 kcal/mile Number of miles extra to lose 1 lb/wk 35 miles or 5 miles/day Number of miles extra to lose 2 lb/wk 70 miles or 10 miles/day 22 22

23 WHAT CONTROLS ENERGY BALANCE? Energy intake Energy expenditure 23 23

24 EATING BEHAVIOR REGULATION Hunger Physiological drive for food Appetite Psychological drive for food Satiety Fulfilling either drive Hypothalamus regulates food intake: Gherlin, Leptin, Endorphins 24

25 WHAT CONTROLS OUR DESIRE TO EAT? 25

26 ENERGY REGULATION Physiological mechanisms help regulate hunger Many hormones play role: Ghrelin: produced in stomach when empty; increases hunger When fat stores increase, leptin in fat tissue signals brain to decrease hunger and food intake. Many people override feedback mechanisms, resulting in energy imbalance 26

27 SATIETY 27

28 GENES INFLUENCE A PERSON S APPETITE, METABOLISM, AND FAT STORAGE 28

29 Body Weight (g) GENETICS CAN DICTATE YOUR SET POINT Forced dietary manipulation Ad libitum fed 350 Overfed Control Food Restricted Days 29

30 GENE-ENVIRONMENT INTERACTIONS IN OBESITY Then: Now: 30 Body Mass Index 30

31 ESTIMATING BODY WEIGHT AND COMPOSITION Weight-for-height tables Body Mass Index (BMI) Waist Circumference 31

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33 WEIGHT AND HEALTH: CALCULATING BMI BMI = weight in pounds x 703 (height, inches) 2 Or weight in kg (height, meters) 2 33

34 BMI (Body Mass Index) is a calculation of weight to height. <18.5 = Underweight = Normal weight = Overweight = Class 1 obesity = Class 2 obesity 40 + = Class 3 obesity 34

35 BMI BMI is a screening tool only. This means that it can not be used as a sole diagnostic tool. Other factors MUST be taken into consideration. 35

36 WAIST CIRCUMFERENCE Although waist circumference and BMI often are interrelated, waist circumference provides an independent prediction of risk over and above that of BMI. Waist circumference measurement is particularly useful in patients who are categorized as normal or overweight on the BMI scale. At BMIs at 35 or over, waist circumference has little added predictive power of disease risk beyond that of BMI. It is therefore not necessary to measure waist circumference in individuals with BMIs 35. HIGH RISK Men: >102 cm ( >40 in.) Women: >88 cm ( >35 in.) 36

37 ASSESSING BODY FAT DISTRIBUTION Upper body (Android) Increased health risks Men waist greater than 40 inches Women waist greater than 35 inches Lower body (Gynecoid) Lower health risks 37

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39 Risk of Associated Disease* According to BMI and Waist Size BMI Classification Waist 40in (M) or 35in (W) Waist > 40in (M) or 35in (W) <18.5 Underweight Normal -- May increase risk Overweight Increased High Obese (Class I) High Very High Obese (Class II) Very High Very High 40 Obese (Class III) Extremely High Extremely High *Type 2DM, HTN, and 39 CVD

40 MEASURING BODY FAT CONTENT Underwater weighing Air displacement BodPod Skinfold thickness Bioelectrical impedance Dual energy X-ray absorptionmetry (DEXA) 40

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