Transcript Chapter Eight - Part One Weight Control Food & Nutritional Health NUT SCI –242 Karen Lacey, MS, RD, CD © Spring 2005

Chapter Eight - Part One
Weight
Control
Food & Nutritional Health NUT SCI –242
Karen Lacey, MS, RD, CD © Spring 2005
Terms
Overweight: 10% - 20% above the
desirable weight for height, or a BMI
of 25.0-29.9
 Underweight: 10% or more below the
desirable weight for height, or a BMI
of less than 18.5
 Obesity: 20% or more above the
desirable weight for height, or a BMI
of 30 or greater

Problems Associated with
Underweight
Due to decreased body fat stores, may
be disadvantaged when energy
reserves may be needed, such as
during physiological stress, injury or
famine
 Other problems include:
– Menstrual irregularity
– Infertility
– Osteoporosis

Problems Associated with
Overweight
High blood pressure
 High cholesterol
 Diabetes
 Heart disease
 Gallbladder disease

I. What is a Healthful
Weight?
Body Weight vs. Body Fat


Body weight and body fat
are not the same thing
Body composition is
important
B. Measuring Body Fat


Difficult to measure
Methods include:
1. Underwater weighing: the entire
body is submerged into a tank of
water and water displacement is
measured to determine body
density and body fat percentage
Cont’d
2.
Biochemical Impedence: estimate
body fat content by measuring how
quickly electrical current is
conducted through the body
– Fat increases resistance against
electrical current
Cont’d
3.
Skinfold Test: thicknesses of
folds of skin various places on
the body are measured with an
instrument called a caliper
 Simple & inexpensive
C. Distribution of Fat

Central obesity: excess fat on the
abdomen and
around the trunk

Central obesity represents a
greater risk to health than fat
elsewhere on the body
D. Weighing in for Health


Health risk is dependent upon three
factors:
1. Body weight
2. Amount & location of body fat
3. Current health status
Waist circumference: a measure
used to assess a person’s abdominal
fat
Cont’d
 Body
Mass Index (BMI): an
index of a person’s weight in
relation to height which
correlates with total body fat
content
II. Energy Balance

Fat stores= energy in – energy out
1. Energy in:
– Calorie content of food taken in
– 3,500 calories = 1 pound of body fat
2. Energy out:
– Basal metabolism: the energy
required to fuel the activities of the
cells necessary to sustain life
Cont’d
Fuel for voluntary activities
– Number of calories an activity uses
is determined by:
Muscle mass required
Weight of body part being moved
Duration of activity
–
III. Causes of Obesity

1.
2.
Genetic vs. Environment
Set-pt. Theory: the theory that the body
tends to maintain a certain weight by
adjusting hunger, appetite and food
energy intake compared to metabolism so
that a person’s effort to alter weight may
be unsuccessful
Fat-cell Theory
Cont’d
2.
3.
4.
Heredity may contribute to obesity
Factors in surroundings encourage eating
 Availability, variety, appearance,
lighting, music, location, companions
External cue theory: the theory that some
people eat in response to such external
factors as the presence of food or the time
of day rather than to such internal factors
as hunger
B. Environment & Behavior
1.
2.
Hunger
 A physiological sensation
 A negative experience people eat to
avoid
Appetite
 A physiological experience
 A positive experience- people eat
for enjoyment
Cont’d
3.
4.
5.
Satiety
 The condition of being full or satisfied
 A signal to stop eating
Other regulators:
 Human sensations
 Emotions
 Situations
 Arousal (ie, stress eating)
Underactivity