Nutrition Ch 8 Energy Balance/ Ch 9 weight management

energy imbalance
causes excessive and deficient body fat
Fat stores of a healthy-weight adult
reserve around 50,000-200,000 kcal’s
body composition
the proportions of muscle, bone, fat and other tissue that makes up a person’s total body weight
body composition differences
Men:
Muscle 45%
Bone 15%
Organs 25%
Fat 15% (13-21% is normal)

Women:
Muscle 35%
Bone 16%
Organs 24%
Fat 25% (23-30% is normal)

lean tissue
muscle, bone, organs
measurements for BMI
kg/m^2
BMI
body mass index- a person’s weight relative to height; determined by dividing the weight (in kg) by the square of the height (in m). Not necessarily a good judge of “overfat” due to athletic body compositions- doesn’t distinguish fat and lean tissue in regard to weight. Shows up differently due to age groups, ethnic and racial groups
BMI measures for obesity
30-34.9 Class I
35-39.9 Class II
>40 Class III
waist circumference
good measure of fat distribution:
upper (android) associated with risks of heart disease, stroke, diabetes, hypertension, camcer
How to measure body composition
skin fold (measures body fat)
bioelectric impedance- low electric current (reduced by fat)
underwater weighing (measures body fat- fat weighs less than water)
Air displacement- bod-pod?
DEXA- fat, fat-free soft tissue, bone mineral density
energy balance
energy in = energy out (Stable body weight)
the energy (kcalories) consumed from foods and beverages compared with the energy expended through metabolic processes and physical activities.
Energy imbalance
positive energy balance: energy intake > energy output — growth, pregnancy, muscle mass build, weight gain
negative energy balance: energy intake < energy output-- dieting, starvation, undernutrition, fasting, diarrhea, excessive exercise, weight loss
Hunger
food-seeking behavior due to lack of food, response to nerve signals and chemical messengers (hypothalamus)
Satiation
the feeling of satisfaction and fullness that occurs during a meal and halts eating. Satiation determines how much food is consumed during a meal
Satiety
the feeling of fullness and satisfaction that occurs after a meal and inhibits eating until the next meal. Satiety determines how much time passes between meals
Satiating
power to suppress hunger and inhibit eating
energy out depends on?
basal metabolism, physical activity, food consumption, adaptation
which all have to do with body temperature, respiration, and heartbeat
Basal metabolism
basic process of life– the energy needed to maintain life when a body is at complete digestive, physical, and emotional rest. About a 2/3 of the energy the average person expends in a day supports the body’s basal metabolism. includes body temp, respiration, heartbeat
physical activity
the most variable expenditure, depends on intensity and duration of the activity and how fit the person is
BMR
Basal metabolic rate: rate of energy use for metabolism under specified conditions: after a 12-hour fast and restful sleep, without any physical activity or emotional excitement, and in a comfortable setting. It is usually expressed as kcalories per kilogram body weight per hour. Higher in those who have considerable lean body mass (fit people and males) and also growing people (children, adolescents, pregnant women), and also with fever or under stress and in people with highly active thyroid glands. Slows down with a loss of lean body mass and during fasting and malnutrition
Thermic effect of food
an estimation of the energy required to process food (digest, absorb, transport, metabolize, and store ingested nutrients); also called the specific dynamic effect (SDE) of food or the specific dynamic activity (SDA) of food. The sum of the TEF and any increase in the metabolic rate due to overeating is known as diet-induced thermogenesis (DIT)
approx 5-10% of energy consumed
Typical person’s energy expenditure
physical activity: 25-35%
thermic effect of food: 5-10%
BMR: 60-65%
obesity
excess fat due to positive energy balance (75% of gain is fat)
bmi 30+
caused by genetics, environment, culture, behavior, socioeconomic status, metabolism
Percentage of obese adults
34% overweight
32% obese (over 60 million people)
66% of US adults
hyperplasia
increase in number of fat cells
hypertrophy
increase in size of fat cells (mostly adults)
lipoprotein lipase
sits on membranes of fat cells and promotes storage of fat
leptin
A protein produced by fat cells under direction of the ob gene that decreases appetite and increases energy expenditure
ghrelin
a protein produced by the stomach cells, works in hypothalamus, that enhances appetite and decreases energy expenditure
levels rise when body is in neg energy balance
Brown adipose tissue
masses of specialized fat cells packed with pigmented mitochondria that produce heat instead of ATP
important in newborns, adults in cold climates, animals in hibernation
successful weight loss
1-2 lbs per rate, 5-10% of initial body weight but as long as vmi is above 19
underweight
Body weight lower than the weight range considered healthy; BMI less than 18.5
overweight
body weight greater than the weight range that is considered healthy; BMI 25 to 29.9