Energy Balance, Body
Composition and Weight
Management
Energy Balance
Definition:
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
5
1
Postabsorptive
influences
Physiological influences
Hunger
2
Sensory
influences
Satiety
Satiety
Satiety
4
Postingestive
influences
3
Satiation
Cognitive influences
Hypothalamus
Glucose
Insulin
Gut hormone
Liver
Gastrointestinal Pancreas
tract
FFA
Leptin
Fat
Modulators of feeding behavior
Name
Site of production
Effect
a-melanocyte stimulating hormone (a-MSH) Hypothalamus
Agouti-related peptide (AGRP)
Hypothalamus
Cocaine-amphetamineregulated transcript (CART) Hypothalamus
Neuropeptide Y (NPY)
Hypothalamus
Inhibition
Stimulation
Peptide YY (PYY)
Ghrelin
G-I tract
G-I tract
Inhibition
Stimulation
Insulin
Pancreas
Inhibition
Leptin
Adipose
Inhibition
Inhibition
Stimulation
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
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%
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
Body Types:
Apple shape:
Pear shape:
•Intra-abdominal
fat.
•Lower-body fat
•Common in men.
•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
Methods Used to Assess Body Fat
Fatfold measures
Hydrodensitometry
Air displacement
plethysmography
Bioelectrical impedance
Dual energy X-ray
absorptiometry (DEXA)
Energy Balance,Body
Composition and Weight
Management
Chapters 8 and 9
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
Chest
Anatomical Landmarks for
Skinfold Measurements
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
Determining
Assess Body Recommended Body
Composition
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
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
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
Environment
Overeating
Present & past eating influences current body wt
Increase availability of convenient food, large portions, energydense 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
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
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
60%
50%
Sovrappeso
Obesi
20%
40%
10 %
30%
27%
13 %
11%
9%
20%
7%
3 1%
10%
23%
28%
26%
24%
Emilia
Puglia
Campania
Calabria
Romagna
(Brindisi)
(Pomigliano
(Lamezia
d'arco)
Terme)
24%
16 %
0%
Lombardia
(Lodi)
Toscana
(Bologna)
Tot ale
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
* Bambini 7-9 anni
e mancanza di studi recenti che utilizzino le soglie IOTF
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
Anni 70
20
21
2008
22
23
24
25
26
27
Distribuzione percentuale dei bambini
per consumo di frutta e verdura. Italia,
2008
37
37
38
38
18
2
3
18
mai
<1 volta a
settimana
qualche
volta a
settimana
2
3
mai
<1 volta a
settimana
2
1 volta al
giorno
da 2 a 4
volte al
giorno
5+ volte al
giorno
2
qualche volta a 1 volta al giorno da 2 a 4 volte al
settimana
giorno
5+ volte al
giorno
Distribuzione percentuale dei bambini per
consumo di bevande zuccherate e/o gassate.
Italia, 2008
36%
24%
18%
17%
6%
mai
<1 volta a
settimana
qualche volta
a settimana
1 volta al
giorno
più volte a
giorno
Consumo di bevande zuccherate e/o gassate
Attività fisica il giorno prima
dell’indagine
≤ 22%

Il 26% dei
bambini non ha
svolto attività
fisica il giorno
precedente
l’indagine
> 22% e ≤ 24%
> 24% e ≤ 27%
> 27%
Attività fisica settimanale
extrascolastica
 Il 25% dei bambini
svolge attività fisica per
non più di un’ora a
settimana
60% 56%
30%
21%
 I maschi tendono a
essere più costanti
 Nei piccoli centri più
che nelle grandi città
0-1
20%
2-3
14%
4-7
numero di giorni con almeno un'ora di attività fisica
Modalità utilizzata dai bambini
per recarsi a scuola
59%
25%
13%
scuolabus macchina
a piedi
1%
2%
bicicletta
altro modo
modalità utilizzata per raggiungere la scuola
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
31
30
10

L’11% dedica a
queste attività più
di 4 ore al giorno
15
11
3–4
>4
3
<1
1
1–2
2–3
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 simple compounds
more complex
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
Examples of each type of metabolism:
Anabolic Pathways
Protein Biosynthesis
Glycogenesis
Gluconeogenesis
Fatty Acid Synthesis
Catabolic Pathways
ATP
Generated
FOR
Provides
Energy
Glycolysis
TCA (Krebs cycle)
ß-oxidation
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.
Il metabolismo dei carboidrati
Tortora, Derrickson Conosciamo il corpo umano © Zanichelli editore 2009
56
Il metabolismo dei carboidrati
Tortora, Derrickson Conosciamo il corpo umano © Zanichelli editore 2009
57
Carbohydrate metabolism
55%
Oxidation
Glucose
20%
Glycolysis
25% Reuptake
45% Brain
10%
Muscle
Il metabolismo dei lipidi
Tortora, Derrickson Conosciamo il corpo umano © Zanichelli editore 2009
59
Fat metabolism
1. 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
Hydrophobic core
Triglyceride
(TG)
Lipoprotein
Density
Chylomicron Low
s
VLDL
IDL
High
LDL
HDL
TG
Hydrophilic surface
Phospholipid
Cholesterol
Protein
Cholesterol Phospholipid Protein
Protein metabolism
Glucose
Protein (Diet)
Protein
Pyruvate
Amino acids
N
E
Amino acids Amino acids
E N
N
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 KrebsHenseleit cycle
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
24
14
Treonina
74
30
7
Triptofano
19
4
3
Valina
93
28
13
TOTALE (esclusa
istidina)
715
231
86
Protein Metabolism
64
Alcohol Metabolism Effects
65
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:
CHO:
Fat:
17 kJ or 4 kcal/g
17 kJ or 4 kcal/g
37 kJ or 9 kcal/g
Energy needs
Measurement of Energy Intake
Metabolic Energy Yields
Fuel
KJ/g
Kcal/g
Fat
38
9
Alcohol
29
7
Carbohydrates 17
4
Protein
4
16
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
 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
Growth







Muscles
Temperature regulation
Osmotic pumps
Protein synthesis
Heart
Respiratory system
Digestive tract
Individual variation
Within individual variation
10%
Factors affecting BMR

1) Body Size & Composition
 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
 Children,
pregnancy
6) Fasting/starvation: BMR
 7) Fever/stress BMR
 8) Smoking/caffeine: BMR

2) Energy Out: Dietary
Thermogenesis
 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
1.
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
2.
3.
4.
5.
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