Energy Balance, Body Composition and Weight Management

Energy Balance Definition: Positive energy balance Calories IN = Calories OUT Positive energy balance Energy intake > energy expended Results in weight gain Negative energy balance Energy intake < energy expended Results in weight loss

Energy In: Food Intake: Physiological/Cognitive Influences Physiological: Empty stomach, gastric contractions, GI hormones, absence of nutrients in small intestine hunger Satiation, satiety – gastric distention, GI hormones, feeling of satisfaction during/after eating stop eating

Hunger, Satiation, and Satiety 1 Postabsorptive influences Physiological influences 5 Hunger Sensory influences 2 Satiety Satiety Satiety Postingestive influences 4 3 Cognitive influences Satiation

Gastrointestinal tract Hypothalamus Liver Pancreas Fat Gastrointestinal tract Hypothalamus Glucose Insulin FFA Leptin Gut hormone

Modulators of feeding behavior Name Site of production Effect a-melanocyte stimulating hormone (a-MSH) Hypothalamus Inhibition Agouti-related peptide (AGRP) Hypothalamus Stimulation Cocaine-amphetamine- regulated transcript (CART) Hypothalamus Inhibition Neuropeptide Y (NPY) Hypothalamus Stimulation Peptide YY (PYY) G-I tract Inhibition Ghrelin G-I tract Stimulation Insulin Pancreas Inhibition Leptin Adipose Inhibition

Energy Out The kcals the body expends: Basal metabolism Physical Activity Digestion, absorption, and processing of ingested nutrients (thermic effect of food)

Components of Energy Expenditure Physical activities Thermic effect of food Basal metabolism

Basal Metabolism Supports the basic processes of life 60 – 70% of the total energy needs Amount of energy needed varies between individuals

Factors affecting Basal Metabolism Age Height Growth Body Composition Fever/Stress Environmental temperature Fasting/Starvation/Malnutrition Hormones 8 8 8 8 8

Energy for Physical Activity Most variable and changeable Significant in weight loss and weight gain Voluntary Increases energy expenditure beyond BMR by 25 – 40%

Thermic Effect of Food (TEF) Energy used to digest, absorb, and metabolize nutrients 6 – 10% above the total energy consumed Protein 20-30% Carbohydrate 5-10% Fat 0-5%

Estimating Energy Requirements Gender – men generally have a higher BMR Growth – BMR is high in people who are growing Age – BMR declines as lean body mass decreases Physical Activity – Vary considerably Body size and composition

Defining Healthy Body Weight Weight within suggested range for ht Fat distribution pattern assoc with low risk of illness Medical history with absence of risk factors Good health supercedes appearance Healthy lifestyle means more than absolute body weight

Weight Classification by BMI Underweight: BMI < 18.5 Healthy Weight: BMI 18.5 – 24.9 Overweight: BMI 25.0 – 29.9 Obesity: BMI >30.0

Defining Obesity Overweight = 10-20% above ideal body weight Mild Obesity = >20% Moderate Obesity > 40% Super Obesity > 80% Morbid Obesity > 100% 9 9 9 9 9

Distribution of Body Fat Central Obesity – Abdominal fat (apple shape) with higher risk of Diabetes Type 2, HTN, CVD Hip and thigh body fat (pear shape) – less harmful Waist circumference: Women > 80-88 cm; Men > 94-102 cm; high risk 12 12 12 12

Energy Balance and Body Composition- FON 241; L. Zienkewicz Body Types: Apple shape: Intra-abdominal fat. Common in men. Pear shape: Lower-body fat Common in women. Energy Balance and Body Composition- FON 241; L. Zienkewicz

Estimating Body Fat Content Measure % body fat Hydrodensitometry: Underwater weighing (most accurate) Fatfold measures/calipers (Triceps, abdomen, thigh, etc) Desirable amount of body fat 21 – 35% for women 8 – 24% for men 13 13 13 13 13

Methods Used to Assess Body Fat absorptiometry (DEXA) Fatfold measures Hydrodensitometry Bioelectrical impedance Air displacement plethysmography Dual energy X-ray absorptiometry (DEXA)

Energy Balance,Body Composition and Weight Management Chapters 8 and 9 1 1 1 1 1

Skinfolds Common field method Relationships among selected skinfold sites and body density Caliper exerts constant tension of 10 g/mm2 Sum of skinfolds indicates relative fatness of individual

Anatomical Landmarks for Skinfold Measurements Chest Abdomen Suprailium Triceps Thigh

Girth Measurements Uses 3 sites: see Appendix F Men: right forearm, abdomen, right upper arm or buttocks Women: abdomen, right thigh, right forearm or right calf Pattern of fat distribution Predicting Body Fat

Waist-to-Hip Ratio Essential and Storage Fat Techniques to Assess Body Composition Determining Recommended Body Weight Predicts disease risk according to “apple” or “pear” shape Disease Risk according to Waist-to-Hip Ratio

Bioelectrical Impedance Hydrated, fat-free body tissues and extracellular water facilitate electrical flow compared to fat tissue because of greater electrolyte content of fat-free component.

Health Risks of Obesity Cardiovascular disease Type 2 Diabetes Hypertension Some cancers Gallbladder disease Osteoarthritis Costly for healthcare system 17 17 17 17 17

Fat Cell Development Fat cells increase in numbers (hyperplastic obesity) and in size (hypertrophic obesity) Fat cell numbers increase most rapidly in later childhood and early puberty; in times of positive energy balance Fat cell size increases when energy intake exceeds expenditure (feasting)

Fat Cell Development Fat cells are capable of increasing their size by During growth, fat cells increase in number. When energy intake exceeds expenditure, fat cells increase in size. When fat cells have enlarged and energy intake continues to exceed energy expenditure, fat cells increase in number again. With fat loss, the size of the fat cells shrinks, but not the number. Fat cells are capable of increasing their size by 20-fold and their number by several thousandfold.

Causes of Obesity Psychological/Environmental Learned response/habit Food satisfies emotional needs stress, boredom, depression, feeling unloved Food as reward External cues time, sight, smell Availability 22 22 22 22 22

Environment Overeating Physical Inactivity Present & past eating influences current body wt Increase availability of convenient food, large portions, energy- dense foods Physical Inactivity Modern technology replaces physical activities Physical activity allows people to eat enough food to get needed nutrients

Environmental Causes (cont) High kcal, high fat foods available; inexpensive, advertised (ex. Fast foods) Physical inactivity: change in modern technology, TV watching Est. that < 1/3 people exercise 30 min./day; 40% do not exercise at all

Causes of Obesity - Genetics Heredity (twin research, adoptive children research) Set-Point Theory Body’s natural regulatory centers maintain homeostasis at set point Human body tends to maintain a certain weight Obesity is the state of very high set point 23 23 23 23 23

Genetic Causes Leptin (ob protein) Hormone produced by adipose tissue Decreases appetite Increases energy expenditure Central fat pattern produces less leptin than peripheral fat More research needed

Genetic Causes - Ghrelin Protein produced by stomach cells Acts as a hormone to decrease energy expenditure, increase appetite

Disease and Mortality Risk Based on BMI 4.6 Even though the risk for premature illness and death is greater for those who are overweight, the risk also increases for individuals who are underweight

Body Composition Changes for Adults in the U.S 15.8 Because of the typical reduction in physical activity, each year the average person gains 0.68 kg of body fat and loses 0.23 kg of lean tissue

OBESITA’ Dati Istat

CONFRONTO TRA DATI RIFERITI E DATI MISURATI DEL SOVRAPPESO E DELL’OBESITA’ NELLA POPOLAZIONE ≥ 18 ANNI Dati riferiti: ISTAT Indagine multiscopo sulle famiglie “Aspetti della vita quotidiana” – Anno 2003 Dati misurati: Ministero della Salute – ISS: Progetto “CUORE” – anni 1998-2002

Dimensioni dell’Obesità negli adulti in Italia Validità delle informazioni disponibili Dati riferiti: gli intervistati tendono a sottostimare l’eccesso di peso - buona rappresentatività, ma probabile sottostima dell’obesità Dati misurati: aree selezionate in modo opportunistico – buona accuratezza, ma il campione potrebbe rappresentare in modo distorto la realtà nazionale Dati riferiti: ♂ 1 su 2 sovrappeso (BMI ≥ 25) ♀ 1 su 3 sovrappeso (BMI ≥ 25) Dati misurati: ♂ 3 su 4 sovrappeso (BMI ≥ 25) ♀ 1 su 2 sovrappeso (BMI ≥ 25)

Dimensioni dell’Obesità infantile in 6 diverse aree Italiane Fonte: Progetto del Ministero della Salute ”Sorveglianza ed educazione nutrizionale basata su dati locali per la prevenzione di malattie cronico-degenerative” anni 2000-2002.

Confronti internazionali, indagini con misurazioni dirette usando le soglie dell’IOTF, 2008 Difficile fare paragoni validi a causa di gruppi di età diversi e mancanza di studi recenti che utilizzino le soglie IOTF * Bambini 7-9 anni

Ma il cambiamento c’è dagli anni ‘70 Distribuzione IMC anni 70 dati INRAN e 2008 OKkio, pool ASL (Abruzzo meno Sulmona, Salerno, Cosenza) 25% mediana anni 70 = 16,3 20% 15% mediana 2008 = 17,9 (n=1784) 10% 5% 0% 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Anni 70 2008

Distribuzione percentuale dei bambini per consumo di frutta e verdura Distribuzione percentuale dei bambini per consumo di frutta e verdura. Italia, 2008

Distribuzione percentuale dei bambini per consumo di bevande zuccherate e/o gassate. Italia, 2008

Attività fisica il giorno prima dell’indagine ≤ 22% > 22% e ≤ 24% > 24% e ≤ 27% > 27% Il 26% dei bambini non ha svolto attività fisica il giorno precedente l’indagine In questo caso, l’attività fisica viene studiata non come abitudine, ma in termini di prevalenza puntuale

Attività fisica settimanale extrascolastica 21% 60% 20% 30% 56% 14% 0-1 2-3 4-7 numero di giorni con almeno un'ora di attività fisica Il 25% dei bambini svolge attività fisica per non più di un’ora a settimana I maschi tendono a essere più costanti Nei piccoli centri più che nelle grandi città

Modalità utilizzata dai bambini per recarsi a scuola modalità utilizzata per raggiungere la scuola 13% 59% 25% 1% 2% scuolabus macchina a piedi bicicletta altro modo

Numero di ore giornaliere dedicate alla TV e ai videogiochi Solo il 3% dei bambini dedica a TV e videogiochi meno di 1 ora al giorno L’11% dedica a queste attività più di 4 ore al giorno 3 10 31 30 15 11 < 1 1 1 – 2 2 – 3 3 – 4 > 4 numero di ore/die dedicate a comportamenti sedentari

Prevention Eat regular meals and limit snacking Drink water in place of high-kcal beverages Select sensible portion sizes Limit daily energy intake to energy expended Limit sedentary activities; be physically active

Role of Metabolism in Nutrition

Metabolism Metabolism – process by which living systems acquire and use free energy to carry out vital processes Catabolism (degradation) Nutrients and cell constituents are broken down for salvage and/or generation of energy Exergonic oxidation Anabolism (biosynthesis) Endergonic synthesis of biological molecules from simpler precursors Coupled to exergonic processes through “high-energy” compounds

Role of Metabolism in Nutrition Definition: the sum of all biochemical changes that take place in a living organism. Group these reactions into two types: anabolic catabolic Reactions: require energy release energy Produce: more complex more simple compounds compounds Modus Operandi: Occurs in small steps, each of which is controlled by specific enzymes.

Relationship Between Catabolic and Anabolic Pathways Catabolic pathways Complex metabolites are transformed into simpler products Energy released is conserved by the synthesis of ATP or NADPH Anabolic pathways Complex metabolites are made from simple precursors Energy-rich molecules are used to promote these reactions 54

Examples of each type of metabolism: Anabolic Pathways Catabolic Pathways Protein Biosynthesis Glycolysis Glycogenesis TCA (Krebs cycle) Gluconeogenesis ß-oxidation Fatty Acid Synthesis Respiratory Chain Other useful generalizations: Some of the steps in the anabolic path (going “uphill”) may not be identical to the catabolic path--but some are shared. ATP Generated Provides Energy FOR

Il metabolismo dei carboidrati Tortora, Derrickson Conosciamo il corpo umano © Zanichelli editore 2009

Il metabolismo dei carboidrati Tortora, Derrickson Conosciamo il corpo umano © Zanichelli editore 2009

Carbohydrate metabolism Glucose 55% Oxidation 20% Glycolysis 25% Re-uptake 10% Muscle 45% Brain

Il metabolismo dei lipidi Tortora, Derrickson Conosciamo il corpo umano © Zanichelli editore 2009

Fat metabolism Triglycerides-----consists of fatty acids major energy component of fat 2. Essential dietary fatty acids-----linoleic, linolenic, arachidonic precursors for membrane phospholipids 3. Cholesterol precursors for steroid hormones and bile acid

Fat metabolism Lipoprotein Hydrophilic surface Hydrophobic core Phospholipid Cholesterol Protein Hydrophobic core Triglyceride (TG) Lipoprotein Density TG Cholesterol Phospholipid Protein Chylomicrons VLDL IDL LDL HDL High Low

Protein metabolism Glucose Protein (Diet) Protein Pyruvate Amino acids 1. Protein synthesis 2. Oxidation 3. Gluconeogenesis-----Krebs cycle, a reversal of glycolysis 4. Ketogenesis-----ketone body (acetoacetate) 5. Ureagenesis-----urea (into urine) through the Krebs-Henseleit cycle Protein metabolism Amino acids Protein (Diet) Protein E N Glucose Pyruvate

Dei 20 aminoacidi contenuti nelle proteine, 9 sono essenziali. Fabbisogno (mg/kg) Lattante (4-6 mesi) Bambino (10-12 anni) Adulto Istidina (29) - Isoleucina 88 28 10 Laucina 150 44 14 Lisina 99 49 12 Metionina e cistina 72 24 13 Fenilalanina e tirosina 120 Treonina 74 30 7 Triptofano 19 4 3 Valina 93 TOTALE (esclusa istidina) 715 231 86

Protein Metabolism

Alcohol Metabolism Effects

How do we employ energy? • MECHANICAL- muscle contraction • ELECTRICAL- maintaining ionic gradients (e.g., Na-K ATPase; 70% of ATP used by kidney & brain used to maintain gradient) • CHEMICAL- biotransformation of molecules (e.g., synthesis degradation, metabolism)

International Unit of Energy: Joule : energy used when 1 Kg is moved 1 meter by a force of 1 Newton : kJ = 103 J; MJ = 106 J : 1 kcal = 4.184 kJ : Protein: 17 kJ or 4 kcal/g CHO: 17 kJ or 4 kcal/g Fat: 37 kJ or 9 kcal/g

Energy needs Measurement of Energy Intake Metabolic Energy Yields

Conversion Efficiency: Food to Usable Energy 40% used to make high energy phosphate bonds 60% “lost” (?) as heat

Energy Balance Sources of fuel for energy Input from diet: carbs, fat, prot, alcohol Stored energy: glycogen, fat, muscle Energy outgo from: Basal metabolism Physical activity “Dietary thermogenesis”

Energy Out Energy of food = Body Energy = ATP Energy out: Overall efficiency 25%, 75% released heat Energy out: 3 main components: Basal Metabolic Rate Thermic Effect Food Physical activity

BMR > Activity > Dietary Thermogenesis

Basal Metabolic Rate BMR = number of calories would need daily simply to stay alive if were totally inactive, in bed, awake for 16 hours & slept for 8 hours Harris-Benedict Equation: Women: 655+(9.56 x weight in kg)+(1.85 x height in cm)- (4.7 x age)=BMR Men: 67+(13.75 x weight in kg)+(5.0 x height in cm)- (6.9 x age)=BMR

1) Basal Metabolic Rate 50-70% Energy Expenditure Maintain basic metabolic processes Cells Muscles Temperature regulation Growth Osmotic pumps Protein synthesis Heart Respiratory system Digestive tract Individual variation Within individual variation 10%

Factors affecting BMR 1) Body Size & Composition 2) Age: Lean tissue BMR Body weight wt lean tissue (but also fat) 2) Age: age Lean tissue 3) Sex: Men lean 4) Activity: Exercise lean tissue

Factors affecting BMR 5) Growth BMR 6) Fasting/starvation: BMR Children, pregnancy 6) Fasting/starvation: BMR 7) Fever/stress BMR 8) Smoking/caffeine: BMR

2) Energy Out: Dietary Thermogenesis Energy to digest, absorb, metabolize food About 10% of calories eaten

2) Thermic Effect of Food 3-6 hours following ingestion ~10% energy intake 2000 kcal diet = 200 kcal TEF Affected by: Meal size/frequency Composition: Protein > Carbs/fat Genetics

3) Energy Out: Physical Activity Physical Activity affected by: Intensity -- how vigorous Time spent Body weight

3) Physical Activity Variable: 20-40% Working muscles require energy Heart/lung extra energy Amt energy used depends on: Muscle mass Body weight Activity nature & duration

Activity Level and Metabolism Activity can account for 20-30% of metabolism Sedentary = Multiplier 1.15 x BMR Light activity (Normal Every day activities) = Multiplier 1.3 x BMR Moderately Active(exercise 3-4 x’s week) = Multiplier 1.4 x BMR Very Active (exercise more than 4 x’s week) = Multiplier 1.5 x BMR Extremely Active (exercise 6-7 x’s week) = Multiplier 1.6 x BMR

Activity Level and Metabolism If you change Light activity (Normal Every day activities) to Moderately Active (exercise 3-4 x’s week) daily caloric burning goes up 7.7% If you change Light activity (Normal Every day activities) to Very Active (exercise more than 4 x’s week) daily caloric burning goes up 23% If you change Light activity (Normal Every day activities) to Extremely Active (exercise 6-7 x’s week) daily caloric burning goes up 38.5%

Energy Requirements Difficult to estimate Direct measurement Research Estimates from averages Based on age/sex Assume light/moderate activity Estimate TEF