Energy Balance, Weight Control and Eating Disorders Part 1 of 2 Chapter 10

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.

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

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 From NHANES

How did we get from a prevalence of 45% to 65%?

Energy Balance Energy intake Energy expenditure

Energy Balance Energy equilibrium Positive energy balance Energy intake equals energy expenditure Positive energy balance Energy intake greater than energy expenditure Negative energy balance Energy intake less than energy expenditure

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

Obesity: A Multifactorial Disorder Genetics Development Behaviors/likes, etc ‘hard wired in’ Environment

Energy Intake 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 Energy intake 11

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 -1000 kcal/day Daily calories to lose 1 pound/week 2100 kcal/day Daily calories to lose 2 pounds/week 1600 kcal/day

Why is reducing kcal so hard? Out of Control Environment Stress and busy schedules Skipped meals Calorie-dense foods Large portions Increased variety

Contributions to Obesity: Learned Behaviors “Clean your Plate” Club Food as a coping mechanism Food for celebration Food is love Food as a reward Food as comfort Learned Behaviors

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

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

It is easy to avoid “expending energy” expenditure 17

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

Measuring Energy Expenditure Direct calorimetry Measures body heat Indirect calorimetry Collecting expired air Stable isotopes Estimated energy requirements (EERs) Harris-Benedict equation

Equations used to estimate energy needs Harris Benedict Women: = 655 + ( 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 3-18

Increase your energy expenditure to lose weight To lose 1-2 pounds/week via exercise, you need to burn 3500-7000 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

What controls energy balance? intake Energy expenditure 23

Eating Behavior Regulation Hunger Physiological drive for food Appetite Psychological drive for food Satiety Fulfilling either drive Hypothalamus regulates food intake: Gherlin, Leptin, Endorphins

Genes influence a person’s appetite, metabolism, and fat storage

Genes influence a person’s appetite, metabolism, and fat storage 100% 90% 50% 0% Rare (Prader Willi, No Leptin production) Leptin: Hormone made in fat tissue that decreases appetite and increases energy expenditure Lipoprotein lipase: enzyme that promotes fat storage More enzyme = more storage Ghrelin: Protein secreted by stomach that stimulates appetite and promotes energy storage Eat anything and not gain weight

Genetics dictate your “set point” Forced dietary manipulation Ad libitum fed

Gene-Environment Interactions in Obesity Then: Now: 30 Body Mass Index

Estimating Body Weight and Composition Weight-for-height tables Body Mass Index (BMI)

Weight and Health: Calculating BMI BMI = weight in pounds x 703 (height, inches)2 Or weight in kg (height, meters)2

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

Risk of Associated Disease* According to BMI and Waist Size Classification Waist ≤ 40in (M) or 35in (W) Waist > 40in (M) or 35in (W) <18.5 Underweight -- 18.5-24.9 Normal May increase risk 25.0-29.9 Overweight Increased High 30.0-34.9 Obese (Class I) Very High 35.0-39.9 Obese (Class II) ≥40 Obese (Class III) Extremely High *Type 2DM, HTN, and CVD

Measuring Body Fat Content Underwater weighing Air displacement BodPod® Skinfold thickness Bioelectrical impedance Dual energy X-ray absorptionmetry (DEXA)