Energy Balance and Body Weight - Chapter 7 Flashcards
Thrifty metabolism
A genetically determined, energy efficient metabolism, requiring few calories for daily activities.
In an enviornment of scarce food, such as found in prehistoric times, a thrifty metabolism allowed the storage of seasonally abudant food as body fat for use in times of food shortage.
In a modern environment with a large surplus of calories, a thrifty metabolism contributes to the development of obesity.
Anabolic
pertaining to anabolism
Catabolic
pertaining to catabolism
Anabolism
Body processes that create more complex chemical compounds for energy storage or for the synthesis of tissue
seen in weight gain
Catabolism
Body processes that break down complex chemical compounds for energy release or for tissue breakdown
in weight loss we are hoping to stimulate catabolism
Where we see anabolism
In infant growth, pregnancy, weight gain, and muscle building
Protein synthesis, triglyceride synthesis, gluconeogenisis
Insulin = hormone that directs anabolism
Adenosine Triphosphate (ATP)
High energy chemical compound used in the body to transfer energy from nutrients to various life processes
energy currency of the body
3 ways we expend energy:
Basal metabolism
Physical activity
Thermic effect of food (TEF)
Basal metabolism
Body processes involving involuntary activities only.
Such as breathing, heartbeat, and chemical reactions
Basal Metabolic Rate (BMR)
Rate at which basal metabolism occurs
Thermic Effect of food (TEF)
Energy expended in digesting, absorving, transportin ,storing, metabolizing, and otherwise handling food.
Amounts to about 10 percent of ingested calories
Resting Energy Expenditure (REE)
The day’s total energy expenditure through basal metabolism only
Factors that increase BMR
Increased lean body mass
Regular or frequent meals
Exposure to cold temperatures
Fever
Caffeine
Stress
Pregnancy and breastfeeding
Factors that decrease BMR
Loss of lean body mass
Meal skipping, dieting, or food restriction
Starvation or fasting
Exposure to warm temperatures
Aging
Female gender
Sleep
Physical activity
Energy expenditure through voluntary physical effort
Harris-Benedict equation for adult men
REE = 66+ 13.7W + 5.0H -6.8A
W = weight in kg
H = height in cm
A = age in years
Harris-Benedict equation for adult women
REE = 655 + 9.6W + 18H - 4.7A
W = weight in kg
H = height in cm
A = age in years
Total Energy Expenditure (TEE)
The sum of energy expenditure through REE, physical activity, and TEF
As percent total energy expenditure (TEE) from BMR decreases…
Percent of energy expenditure from physical activity (AEE) increases
Which is the most variable component of total energy expenditure?
Activity energy expenditure (AEE)
What does Thermic effect of food (TEF) depend on?
Type of food eaten (pure protein will induce a higher thermic effect than fat)
Quantity ingested
Whether a meal is followed by exercise, which increases the thermic effect of food
*TEF of obese people ie less than TEF of normal-weight people
Body Mass Index (BMI)
A heigh-weight relationship used to assess obesity.
Equal to weight in kilograms over height in meters squared
weight (kg)
height (m) squared
prevalence
The number of cases of a condition in a given population or the proportion of the population suffering from that condition
Relative risk
The increase in risk seen in a high risk group over that seen in the lowest risk group
Total body mass
Sum of lean tissue mass and fat mass
Body Impedance Analysis (BIA)
A method of measuring body composition utilizing the fact that lean tissue, with a high water content, conducts electricity relatively well, while fat tisue, with a low water content, conducts electricity poorly
If a mild electric current is passed through the body, the body’s impedance, or resistance to current flow, indirectly indicates its fat content
Three fat depots
Subcutaneous fat
Visceral fat
Intramuscular fat
Subcutaneous fat
The body fat depot found right under the skin
when you pinch your skin
Visceral or abdominal fat
The body fat depot found inside the abdominal cavity
Intramuscular fat
The body fat depot found interspersed within the muscle fibers
Android obesity
“apple shape”
A pattern of body fat distribution in which most body fat is carried abdominally
more often in men
higher risk of hypertension, type II, and heart disease
greater health problems of the two obesities
Gynecoid obesity
“pear shape”
A pattern of body fat distribution in which most body fat is carried on the hips and thighs
more often in women
Hip to waist ratio
A measure used to define android obesity
A value of greater than 1:1:! is considered to indicate such
Set point theory
The notion that one’s body tends to gravitate to a particular weight
governed by the hormone leptin - diminishes appetite
How is body fat stored?
Adipose tissue
Amenorrhea
A cessation of normal menstruation caused by inadequate estrogen levels resulting from excessively low body fat.
Causes bone mineral loss leading to weakend bones
Female athlete triad
The bombinatino of low bone density, amenorrhea, and eating disorder sometimes seen in female athletes with very little body fat
Adipose’s other important functions
Reproduction
Shock absorption
Thermal insulation
Two ways adipose tissue grows
Increase in number of cells (hyperplasia)
Increase in cell size (hypertrophy)
Hyperplasia
Tissue growth through an increase in cell number
weight gain through hyperplasia is harder to lose
occurs more in growing children
Hypertrophy
Tissue growth through an increase in cell size
adults gain weight through hypertrphy up to a point
Very Low Calorie Diets (VLCD)
diets less than 1200 kcals per day
two variations: extreme restrictions using normal foods, liquid diets
Bariatric
Of or pertaining to body weight
gastric bypass operations, stomach stapling
i.e. bariatric surgery
3 drugs on market for weight loss
sibutrimine - supress appetite and increase metabolism
phentermine
orilstat - blocks fat absorption
Drugs never indicated for weight loss
Diuretics - cause water loss and electrolyte imbalance
Laxatives - rebound constipation on withdrawl
Amphetamines - addictive and dangerous class of illegal drugs
The way to lose weight
Go into negative energy balance
What generates mot of our metabolism?
lean body mass, including muscle
Dieter’s Dilemma
The more weight you lose, the less energy you need, until your requirements get so low.
