Nutrition Ch. 10- Energy Balance & Weight Control

subcutaneous fat

"under skin" -insulates body against cold temp. and protects muscles and bones from bumps and bruises. -unevenly distributed and can become thicker in certain regions of the body (ex: abdominal region) -contains adipose cells (women usually have more sub-c fat than men)

Brown fat cells

(BAT: brown adipose tissue) -specialized adipose cells that are more richly supplied with blood and contain more mitochondria than white fat cells -uses fat for generating heat -more common/important in infants than in adults

central body fat distribution

(apple shape) more common in men and black women who tend to store extra visceral fat in the central region of their bodies

energy intake

(biological fuels) calories from foods and beverages that contain macronutrients and alcohol

fat-free mass

(lean tissues) comprised of body water; mineral-rich tissues such as bones and teeth; and protein-rich tissues, including muscles and organs

lower body fat distribution

(pear shape) more common in women who tend to store extra subcutaneous fat below the waist in the butt and thighs

bariatric surgical procedures

-Roux-en-Y gastric bypass surgery -gastric banding procedure both operations can be preformed laparoscopically (insert video cameras in abdomen) -sleeve gastrectomy

osteoarthritis

-a painful chronic condition that affects joints and interferes with the person's ability to move. -overweight/obese ppl are more likely to develop

Our environment affects our:

-appetite -whether we choose to be sedentary or physically active ex: elevators/garage door openers

Factors that influence basal metabolism

-body composition -gender -body surface area -age -calorie intake

sleep apnea

-condition that causes breathing to stop periodically during sleep. -obese people are more likely to suffer from this condition.

visceral fat

-contains adipose cells -forms a protective structure that is under the ab muscles and hangs over the stomach and intestines (men usually have more V fat than women)

The body is composed of 2 major compartments:

-fat-free mass -total body fat

factors that increase the metabolic rate

-fever -stimulant drugs (caffeine) -pregnancy -milk production in a woman who has given birth -recovery after exercise

factors that contribute to underweight

-genetics -lifestyle practices -chronic diseases -psychological disturbances

The BMI may overestimate body fat in ppl who have lost muscle tissue as a result of aging or illness. Therefore, who should BMIs NOT be applied to?

-highly muscular people -elderly -chronically ill people

low-carb fad diet approach

-limit carbohydrate intakes, high in protein and saturated fat -usually results in rapid weight loss at first b/c the body loses water -ex: Atkins, south beach, scarsdale diet

typical fad diet

-offers a "quick fix" -limits food selections and groups -requires buying a book, diet supplement pills, etc -unscientific claims -testimonials -does not emphasize the need to change eating habits or physical activity patterns

Roux-en-Y gastric bypass

-reduces patients stomach capacity from 32 oz to 1.5 oz -surgeon cuts the small int. and attaches the lower end to the newly formed stomach pouch so digestion and absorption are reduced

Sleeve gastrectomy

-reduces stomach size -but does not involve an intestinal bypass so nutrient absorption is not reduced -not reversible b/c the unused portion of the stomach (that secretes ghrelin, the hunger hormone) is removed

adjustable gastric banding

-surgeon creates & determines the size of the stomach with an adjustable band instead of surgical staples -reversible -many complications (band slipping, etc.)

dietary supplements for weight loss

-these products generally have not been scientifically tested in humans for safety and effectiveness -not recommended by medical experts -serious side affects/death can result ex: ephedra: natural stimulant found in most dietary supplements, banned by FDA

There is no direct way to measure a living person's percentage of body fat. What are some of the indirect methods scientists can use?

-underwater weighing -dual-energy x-ray absorptiometry (DXA) -air displacement -bioelectrical impedance -skinfold thickness

4 key elements for successful weight loss and long-term weight maintenance

1. motivation 2. calorie reduction 3. regular physical activity 4. behavior modification

healthy body fat percentage for women

23-31%

how many kcal are in a pound?

3,500

for the typical active person, basal metabolism accounts for __?__ percent of body's total energy use

60-75%

people with BMIs greater than 25 have increased risks of:

CVD hypertension type 2 diabetes

leptin

a hormone secreted by fat cells that reduces hunger and inhibits fat storage in the body -a person's blood leptin level is directly proportional to their amount of body fat

adenosine triphosphate (ATP)

biological compound that stores energy

Our bodies use a mixture of ____ and ____ to do its work

biological fuels and oxygen

resting metabolic rate (RMR)

body's rate of energy use a few hours after resting and eating -slightly higher than your BMR

basal metabolism includes energy needs for

breathing and circulating blood

energy equilibrium

calorie intake (from food/drink) equals calorie output (basal metabolism/physical activity/TEF/NEAT)

positive energy balance

calorie intake is greater than calorie output -weight gain as your body stores excess dietary fat in adipose cells -occurs during periods of growth -necessary for pregnant women

negative energy balance

calorie intake is less than calorie output -body metabolizes stored fat for energy -weight loss results as your adipose cells shrink

energy output (energy expenditure)

calories cells use to carry out their activities

energy

capacity to perform work The total amount of energy is constant, the amount remains the same bc energy cannot be created nor destroyed

adipose cells

cells that are store energy in the form of triglycerides (FAT)

obesity

condition characterized by an excessive and unhealthy amount of body fat

central-body obesity

condition characterized by excessive abdominal fat

female athlete triad

condition characterized by low energy intakes, abnormal menstrual cycles, and bone mineral irregularities

appetite

desire to eat appealing food -affected by environment, particularly food advertisement

bulimia nervosa

eating disorder characterized by cyclic episodes of bingeing and calorie-restrictive dieting -purging

thermic effect of food (TEF)

energy used to digest foods and beverages as well as absorb and further process the macronutrients

eating "cues"

environmental factors that stimulate eating behavior. can be thought of as problem behaviors and obese people must correct and modify these behaviors if they wish to loose weight.

total body fat

essential fat and adipose tissue

hyperthyroidism

excess thyroid hormone production symptoms: sweaty, nervous, rapid heart rate, diarrhea, weight loss despite increased appetite

Formula to calculate metabolic energy needs

for men = 1.0kcal/kg/hr for women- .9kcal/kg/hr

overweight

having extra weight from bone, muscle, body fat, and/or body water. Ex: a pro football player can be overweight bc of his muscular body build

Leptin, CCK. and PYY

inhibit hunger sensations

non exercise activity thermogenesis(heat production) "NEAT"

involuntary skeletal muscular activities -fidgeting -do not consciously control

socioeconomic factor that influences eating behavior

level of education/income. ex: most of the percentage of those who are obese have less than a high school education

a quick and easy method to determine your risk of obesity-related disorders is to....

measure your waist circumference. central-body obesity is defined by a waist circumference of men: > 40 inch. women: > 35 inch.

bariatric medicine

medical specialty that focuses on the treatment of obesity

Air displacement

method of estimating body composition by determining body volume. Done with a device called the BOD POD:measures the volume of air in the chamber with the person in it and compares the value w/ the volume of air that was in the unoccupied chamber Advantage: accurate Disadvantage: expensive, not practical

basal metabolism (BMR)

minimal # of kilocalories the body uses to support vital activities after fasting and resting for 12 hours -breathing -circulating blood -maintaining constant liver,brain, kidney functions

psychological factor that influences eating behavior

mood and self-esteem obesity can increase the likelihood of depression, especially in American women

"thrifty" metabolism

more efficient at storing excess energy as fat. -if you gain weight easily you may have inherited a thrifty metabolism

why might muscular people have BMIs in the overweight range yet have healthy percentages of body fat?

muscle is denser than fat

hypothyroidism

not producing enough thyroid hormone and as a result you have a lower-than-normal metabolic rate. symptoms: feeling cold, lack energy, constipation, weight gain

BMI (Body Mass Index)

numerical value of relationship between body weight and risk of chronic health problems associated with excess body fat

weight plateau

occurs when a person reduces their calorie intake and increases physical activity, thus reaching "energy balance"

underweight

person with a BMI under 18.5

ghrelin

protein/hormone secreted by the stomach that stimulates eating behavior

eating disorders

psychological disturbances that lead to certain physiological changes and serious health complications

by maintaining a balanced energy state, your weight will

remain relatively stable over time

set-point theory

scientific notion that body fat content is genetically predetermined

thyroid hormone

secretion of the thyroid gland that regulates metabolism

satiety

sense that enough food or beverages have been consumed to satisfy hunger -size of stomach influences satiety.

anorexia nervosa

severe eating disorder characterized by self-imposed starvation

societal factor that influences eating behavior

societal pressures. ex: the ideal female figure = slim but curvy models, actresses...`

hypothalamus

structure in the brain that controls hunger and satiety

cellulite

subcutaneous fat held in place by irregular bands of connective tissue. -there are no effective ways to smooth the skin's dimpled appearance

liposuction

surgical method of reducing the size of local fat deposits, suctions the excess subcutaneous fat out of body -cosmetic; not intended to treat obesity -many risks -most common type of cosmetic surgery in US

Skinfold Thickness

technique of estimating body comp. in which calipers fare used to measure the width of skin folds at multiple body sites (triceps etc) Advantages: easy, inexpensive Disadvantages: the accuracy depends on the skill of the person taking measurement

Bioelectrical Impedance

technique of estimating body composition in which a device measures the conduction of a weak electrical current through the body Body fat resists the flow of electricity bc fat contains less water and electrolytes than lean tissue. Advantages: quick, painless, accurate Disadvantages: devices available for consumers may be inaccurate

Underwater weighing

technique of estimating body composition that involves comparing weight on land to weight when completely submerged in a tank of water. -A person who has more body fat will weigh less when under water than a person who has more lean tissue b/c lean tissue is denser than water and fat tissue is not as dense as water. Advantages: fairly accurate Disadvantages: not convenient, $$$

Dual-energy X-Ray absorptiometry (DXA)

technique of estimating body composition that involves scanning the body with multiple low-energy x-rays. Gives a detailed pic of internal structures including fat deposits Advantage: highly accurate Disadvantage: equipment=expensive

"white fat"

the majority of adipose cells are creamy white or yellow and are referred to as "white fat" -main job for white fat tissue it to store* fat

high fructose intakes may result in weight gain b/c...?

the sugar decreases satiety (the feeling of being full) and stimulates fat synthesis in the body

children are more likely to become oversight or obese if...

their mothers were overfat prior to becoming pregnant or if they smoked during pregnancy

main hormone that influences BMR

thyroid hormone levels

fad

trendy practice that has widespread appeal for a period, then becomes no longer fashionable. -fad diets rely on gimmicks -adkins, south beach duet, the rice diet, the beverly hills diet etc.

hunger

uncomfortable feeling that drives a person to consume food

very-low-fat fad diet approach

very high carbohydrate intake -usually results in rapid weight loss when followed consistently -not harmful for healthy adults, just not a tasty diet, hard to follow -ex: pritikin diet, dr. dean ornish's "eat more, weight less" diet plan.

fat deposits under abdominal muscles

visceral

physical activity

voluntary skeletal muscle movement. -increases energy expenditure above basal energy needs

BMI formula

weight (lb) ------------------------------------ [height (in)] squared X 703