chapter eight - part one weight control food & nutritional health nut sci –242 karen lacey,...
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Chapter Eight - Part One
Weight Control
Food & Nutritional Health NUT SCI –242Karen 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 pressureHigh cholesterolDiabetesHeart diseaseGallbladder 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 requiredWeight of body part being movedDuration of activity
III. Causes of Obesity
Genetic vs. Environment
1. 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
2. Fat-cell Theory
Cont’d
2. Heredity may contribute to obesity
3. Factors in surroundings encourage eating Availability, variety, appearance,
lighting, music, location, companions
4. 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. Hunger A physiological sensation A negative experience people eat to
avoid2. Appetite
A physiological experience A positive experience- people eat
for enjoyment
Cont’d
3. Satiety The condition of being full or satisfied A signal to stop eating
4. Other regulators: Human sensations Emotions Situations Arousal (ie, stress eating)
5. Underactivity