1

KNH 411

IntakeMeasured in kilojoules (kJ) or kilocalories (kcal) -

food energyDetermined by bomb calorimeterNutrition Facts label, food composition tables,

dietary analysis software

24-Hour Energy Expenditure (EE)Resting energy expenditure (REE)Thermic effect of foodPhysical activity

Resting energy expenditure (REE)Sustain life, keep vital organs functioning60-75% of EE, 1 kcal/kg body wt./hr factors affecting REE

Lean body massMale sexBody temperatureAgeEnergy restrictionGenetics

Basal energy expenditure (BEE)

Difficult to measure

Thermic effect of food (TEF)Measured for several hours postprandialDigest, absorb, metabolize, store, and eliminate

nutrients 10% of EE

Physical Activity EEMost variable20-25% of EE Influenced by body weight, number of muscle groups

used, intensity, duration and frequency of activity

MethodsEquations Indirect calorimetryDoubly-labeled waterDirect calorimetry

Equations for estimating EEHarris-Benedict made in 1900’s WHO IOM DRI – estimated energy requirement (EER)

Includes physical activity (PA) coefficient Separate calculations for overweight adults and

overweight children and adolescents – based on BMI

© 2007 Thomson - Wadsworth

© 2007 Thomson - Wadsworth

© 2007 Thomson - Wadsworth

© 2007 Thomson - Wadsworth

Indirect CalorimetryMetabolic research or critically ill patientsMeasures inspired and expired air by minute

ventilationEE proportional to oxygen consumption and carbon

dioxide production

Doubly Labeled Water “Gold standard” 2 stable isotope forms of water Rate at which isotopes disappear is measured in

urine over 2-week period

Direct CalorimetryChamber which measures heat expired through

evaporation, convection, and radiationRarely available

Interaction of nervous and endocrine systemsOrexigenicAnorexigenicAdaptive thermogenesis

Appetite stimulated by hypothalamusSecretions of pancreatic and GI hormones Increase and decrease appetite and food intakePradar-Willi syndrome

Hormones affecting appetite & food intake InsulinGlucagonAmylin decreases appetiteCholecystokinin (CCK) hormones; decrease

appetiteGlucagon like peptide-1 hormones; decrease

appetitePeptide YY hormones; decrease appetite Ghrelin

Adipocyte – fat cell; mostly TG

Storage site - 90% energy reserves

Other functions

White fat (WAT) vs. brown fat (BAT)

Lipogenesis

© 2007 Thomson - Wadsworth

Adiponectin and leptin stimulate storage

Hypertrophy and hyperplasia of cells

“Adiposity rebound”

“Two compartment model” – fat vs. fat-free mass

Use of height and weight – BMI commonly used to assess obesityDoes not directly measure fatnessClinical judgment should be used

Body Mass Index (BMI)Obese ≥ 30

calculation and classifications

BMI percentiles CDC growth chartsPediatric population≥ 95%th percentile = obesity≥ 85%th percentile = overweight

Important predictor of health status

Abdominal/central body fatApple, android

Lower body fatHips and thighs, pear, gynoid

Measured by waist circumference and waist-to-hip ratio

Waist circumference Increased risk of type 2 DM, htn., dyslipidemia,

CHD, metabolic syndrome> 40 in. males, > 35 in. females – “high risk”

Waist-to-hip ratio (WHR)Waist circumference/hip circumferenceDisease risk increases with WHR > 0.95 in males

and >0.8 in females

Key concept: fat deep within abdomen and around intestines and liver increases disease risk

“Globesity,” “epidemic”

In the U.S. - NHANES dataSignificant increases

Canada

Europe: 45-80% of population

By race, ethnicity, SES, age

“The age of caloric anxiety”

Type 2 diabetes

High blood pressure

CHD

Cancer

Mortality

Chronic energy intake exceeding energy expenditure

Key contributors:Medical disorders and treatmentGeneticsObesigenic environment

Medical disorders and treatmentCushings syndrome, hypothyroidism, Prader-WilliPharmacological agentsSmoking cessationNight eating syndromeBinge eating

Genetics 40-50% of BMI explained by genetics Influences taste, appetite, intake, expenditure, NEAT,

storage “Set-point” theoryMultiple genes Predictive in families – parents & twins

80% of offspring with 2 obese parents 40% of offspring with 1 obese parent MZ twins more likely than DZ twins

Obesigenic environment “Toxic food environment” – convenient availability of

low-cost, tasty, energy-dense foods in large portionsEvidence supports low-energy-dense foods for satiety

Soups, fruits, vegetables, cooked whole grains Barriers – cost and convenience

Two-step processAssessmentManagement

NIH algorithm for treatment

© 2007 Thomson - Wadsworth

AssessmentBMI & waist circumferenceCurrent chronic diseasesDiet and physical activity habitsPatient’s readiness to lose weight Identify and address barriers, coping skills, self-

efficacyBehavioral assessment

ManagementUse of recommended therapiesControl of factors known to increase risk of morbidityTherapies include – diet, physical activity, behavioral

therapy, bariatric surgery, pharmacologic treatmentLose 10% in 6 mo.

Nutrition therapyReduce intake 500-1000 kcal/d.Lose 1-2 lbs./weekNIH low-kcalorie diet Minimize CVD risk factors – NCEP Therapeutic

Lifestyle Changes diet1000-1200 kcal/d women, 1200-1600 kcal/d men

minimumUnclear whether altering macronutrient levels is

beneficial

© 2007 Thomson - Wadsworth

Physical ActivityCrucial for weight maintenanceMinimum 30-45 min moderate activity 3-5 days/week Initiate slowly and graduallyCan be programmed or lifestyle activities

Behavior TherapyTechniques for identifying and overcoming barriers

Self-monitoring Stimulus control Rewards

Pharmacologic TreatmentBMI ≥ 30 or ≥ 27 with risk factorsConsider cost and side effects, and rebound weight

gainLong-term use

Sibutramine (Meridia) Orlistat (Xenical)

Others for short-term use

SurgeryBariatric surgery – BMI ≥ 40 or ≥ 35 with risk factorsRoux-en Y gastric bypass, vertical banded

gastroplasty, adjustable band gastroplastyAssess benefits vs. risksPreoperative screening & education important