Livro DRI 2006 (Micronutrientes)

Livro DRI 2006 (Micronutrientes)


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greatly among
individuals and from day to day. In sedentary people, about two-thirds of total
energy expenditure (TEE) goes to sustain basal metabolism over 24 hours (the
BEE), while one-third is used for physical activity. In very active people, 24-
hour TEE can rise to twice as much as BEE, while even higher total expendi-
tures can occur among heavy laborers and some athletes.
In addition to the immediate energy cost of individual activities, exercise
induces a small increase in energy expenditure that persists for some time after
an activity has been completed. The body\u2019s excess post-exercise oxygen con-
sumption (EPOC) depends on exercise intensity and duration and has been
estimated at some 15 percent of the increment in expenditure that occurs dur-
ing the activity.
Physical activity level: The ratio of total to basal daily energy expenditure
(TEE:BEE) is known as the Physical Activity Level (PAL). PAL categories are
defined as sedentary (PAL \u2265 1.0 < 1.4), low active (PAL \u2265 1.4 < 1.6), active
(PAL \u2265 1.6 < 1.9), and very active (PAL \u2265 1.9 < 2.5). In this publication, PAL is
used to describe and account for physical activity habits (see Part II, \u201cPhysical
Activity\u201d).
Total energy expenditure: Total energy expenditure (TEE) is the sum of the
basal energy expenditure, the thermic effect of food, physical activity, thermoregu-
lation, and the energy expended in depositing new tissues and in producing
milk. With the emergence of information on TEE by the doubly labeled water
method, it has become possible to determine the energy expenditure of infants,
children, and adults in free-living conditions. It refers to energy expended dur-
ing the oxidation of energy-yielding nutrients to water and carbon dioxide.
Copyright © National Academy of Sciences. All rights reserved.
Dietary Reference Intakes: The Essential Guide to Nutrient Requirements
http://www.nap.edu/catalog/11537.html
88 DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS
DETERMINING DRIS
Estimated Energy Requirement
The Estimated Energy Requirement (EER) is defined as the average dietary en-
ergy intake that is predicted to maintain energy balance in a healthy adult of a
defined age, gender, weight, height, and a level of physical activity that is con-
sistent with good health. There is no RDA for energy because energy intakes
above the EER would be expected to result in weight gain.
To calculate the EER for adults, prediction equations for normal-weight
individuals (BMI of 18.5\u201325 kg/m2) were developed using data on total daily
energy expenditure as measured by the DLW technique (see Table 1). In chil-
dren and in pregnant or lactating women, the prediction equations for the EER
account for the additional needs associated with the deposition of tissues or the
secretion of milk at rates that are consistent with good health.
Criteria for Determining Energy Requirements,
by Life Stage Group
Life stage group Criterion
0 through 6 mo Energy expenditure plus energy deposition
7 through 12 mo Energy expenditure plus energy deposition
1 through 18 y Energy expenditure plus energy deposition
> 18 y Energy expenditure
Pregnancy
14 through 18 y Adolescent female EER plus change in TEE plus pregnancy
energy deposition
19 through 50 y Adult female EER plus change in TEE plus pregnancy
 energy deposition
Lactation
14 through 18 y Adolescent female EER plus milk energy output minus
 weight loss
19 through 50 y Adult female EER plus milk energy output minus weight
 loss
Factors That Affect Energy Expenditure and
Requirements
Body composition and body size: Although body size and weight exert appar-
ent effects on energy expenditure, it is disputed whether differences in body
composition quantitatively affect energy expenditure. It is unlikely that body
Copyright © National Academy of Sciences. All rights reserved.
Dietary Reference Intakes: The Essential Guide to Nutrient Requirements
http://www.nap.edu/catalog/11537.html
PART II: ENERGY 89
composition markedly affects energy expenditure at rest or the energy costs of
physical activity in adults with BMIs of 18.5\u201325 kg/m2. In adults with higher
percentages of body fat, mechanical hindrances can increase the energy expen-
diture associated with certain activities.
The proportion of fat-free mass (FFM) is the major parameter in determin-
ing the rate of energy expenditure under fasting basal metabolic rate (BMR) and
resting metabolic rate (RMR) conditions. RMR/kg of weight or RMR/kg of FFM
falls as mass increases because the contributions made by the most metaboli-
cally active tissues (the brain, liver, and heart) decline as body size increases.
Findings from different studies suggest that low energy expenditure is a
risk factor for weight gain in a subgroup of people susceptible to excess weight
gain, but not in all susceptible people and not in those with a normal level of
risk. These data are consistent with the general view that obesity is a multi-
factorial problem.
Physical activity: The increased energy expenditure that occurs during physi-
cal activity accounts for the largest part of the effect of activity on overall energy
expenditure. Physical activity also affects energy expenditure in the post-exercise
period, depending on exercise intensity and duration, environmental tempera-
tures, one\u2019s state of hydration, and the degree of trauma to the body. This effect
lasts for as many as 24 hours following exercise.
Spontaneous non-exercise activity reportedly accounts for 100\u2013700 kcal/
day. Sitting without fidgeting or sitting with fidgeting raises energy expenditure
by 4 or 54 percent, respectively, compared with lying down. Standing while
motionless or standing while fidgeting raises energy expenditure by 13 or 94
percent, respectively.
Gender: There are substantial data on the effects of gender on energy expendi-
ture throughout the lifespan. Gender differences in BMR are due to the greater
level of body fat in women and to differences in the relationship between RMR
and FFM.
Growth: Energy requirements in infants and children include the energy asso-
ciated with the deposition of tissues at rates consistent with good health. The
energy cost of growth as a percentage of total energy requirements decreases
from around 35 percent at age 1 month to 3 percent at age 12 months. It re-
mains low until the adolescent growth spurt, when it then increases to about 4
percent. The timing of the adolescent growth spurt, which typically lasts 2 to 3
years, is also very variable, with the onset typically occurring between ages 10
and 13 years in the majority of children.
Copyright © National Academy of Sciences. All rights reserved.
Dietary Reference Intakes: The Essential Guide to Nutrient Requirements
http://www.nap.edu/catalog/11537.html
90 DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS
Older age: All three major components of energy expenditure (RMR, TEF, and
energy expenditure of physical activity [EEPA]), decrease with aging. There is
an average 1\u20132 percent decline per decade in men who maintain constant weight.
The suggested breakpoint for a more rapid decline appears to occur at approxi-
mately age 40 years in men and age 50 years in women. For women, this may
be due to an accelerated loss of FFM during menopause. PAL has been shown
to progressively decrease with age and is lower in elderly adults compared to
young adults.
Genetics: Individual energy requirements substantially vary due to combina-
tions of differences in body size and composition; differences in RMR indepen-
dent of body composition; differences in TEF; and differences in physical activ-
ity and EEPA. All of these determinants of energy requirement are potentially
influenced by genetics, with cultural factors also contributing to variability.
Ethnicity: Data from studies of adults and children indicate that the