1. Energy Balance, Body Composition and Weight Management

2. 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

3. 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

4. Hunger, Satiation, and Satiety1
Postabsorptive
influences
Physiological influences 5
Hunger
Sensory
influences 2
Satiety
Satiety
Satiety
Postingestive
influences 4 3
Cognitive influences
Satiation

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

6. 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

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

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

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

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

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

12. 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%

13. 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

14. 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

15. 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

16. 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

17. 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 > cm; Men > cm; high risk 12 12 12 12

18. 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

19. 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

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

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

22. 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

23. Anatomical Landmarks for Skinfold Measurements
Chest
Abdomen
Suprailium
Triceps
Thigh

24. 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

25. 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

26. 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.

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

28. 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)

29. 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.

30. 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

31. 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

32. 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

33. 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

34. 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

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

36. 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

37. 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

38. OBESITA’
Dati Istat

39. 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

40. 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)

41. 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

42. 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

43. 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

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

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

46. 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

47. 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

48. 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

49. 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

50. 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

51. Role of Metabolism in Nutrition

52. 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

53. 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.

54. 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

55. 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

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

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

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

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

60. 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

61. 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

62. 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

63. 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

64. Protein Metabolism

65. Alcohol Metabolism Effects

66. 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)

67. 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 = kJ
: Protein: 17 kJ or 4 kcal/g
CHO: 17 kJ or 4 kcal/g
Fat: 37 kJ or 9 kcal/g

69. Energy needs
Measurement of Energy Intake
Metabolic Energy Yields

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

71. 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”

72. 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

73. BMR > Activity > Dietary Thermogenesis

74. 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

75. 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%

76. 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

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

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

79. 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

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

81. 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

82. 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

83. 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%

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