Chapter 9
body composition
another way to assess body weight ration of body fat to lean tissue excess body fat increases health risk whereas having more lean tissue does not
thyroxine
more=increases BMR lowest when we sleep made by iodine
thermic effect of food
10% of total energy TEF can vary -bigger meal= higher TEF -high fat= lower TEF why? bc fat can be used and stored more efficiently
environmental and life style and obesity
-enticements to eat (readily available food/food advertisements) -sedentary lifestyle will make you obese
ABCs of behavior modification
1. ID antecedents (what caused it) -use a food diary 2. recognize the behavior -id behaviors that cause weight gain 3. see the consequences -physiological/psychological 4. modify behavior -empowerment/plan/gradual 5. enjoy new consequence
what decreases BMR?
1. age: as you get older you lose lean body mass 2. fasting/starvation: body conserves energy and lowers BMR 3. resting position: lowest when lying down 4. under active thyroid gland: secrete less thyroxine so decreases BMR
successful long term weight loss management involves:
1. decreasing energy intakes 2. increasing physical activity 3. modifying behavior
factors that cause satiety
1. distention of the stomach due to food 2. intestinal distension and presence of nutrients in small intestine - hypothalamus is informed that meal was consumed; brain triggers satiety hormones 3. nutrient levels in circulating blood
reasons why we are eating more
1. food is more readily available 2. availability of food stimulates our appetite 3. portion sizes (have increased 2-5 larger--> we will eat this) 4. Social changes (more fast food; busier so less meals are prepared) (more single parent/double working parent households) 5. imbalance of energy (less energy at work, home, and play)
tools to aid us in keeping up with calories consumed
1. food labels (portion/ serving size) 2. nutritional database (USDA Food composition) 3. MyPlate (plans diet/guidance on types and how much food to eat) 4. Nutritional fitness apps
steps for gaining weight
1. medical evaluation for low wt. -rule out medical condition 2. gradually introduce energy dense foods 3. strength and endurance exercises
5 factors that influence hunger/appetite
1. sight, smell, taste, of food 2. contraction of an empty stomach 3. low nutrient levels in small intestine/blood 4. Ghrelin 5.physiological factors (comfort)
factors that increase BMR
1. thyroxine 2. age/growth 3. height 4. body comp 5. exercising 6. gender 7. pregnancy 8. environmental temperature 9. fever
energy required for physical activity
15-30% of total energy expenditure
DGA for americans and physical activity
150 min for moderate intense aerobic activity -some may need more -some may need to do this gradual (ppl who don't often exercise)
healthy body fat level for women
21-32%
how much percent is basal metabolism of total energy expenditure
60-75%
healthy body fat level for men
8-19%
underweight
<18.5
obese
>30 kg/m2
morbid obesity
>40 kg/m2
underwater weighing
A method of estimating total body fat by weighing the individual on a standard scale and then weighing him or her again submerged in water difference between the two weights is used to estimate total body volume.
healthy weight
BMI 18.5-24.9 weight that minimizes health risk
when is waist circumference not useful
BMI greater than 35
exercise increases
BMR
monetary costs of obesity
Higher health care costs and decreased productivity in the work place
health risks of being underweight
If an individual is predisposed to be naturally thin: no risks associated with being underweight. May have a decreased risk for developing certain chronic diseases If being underweight is self-induced or the result of a disease state: immune system will be compromised; increased health risks
psychological costs of obesity
Increased risk of depression, negative self-image, feelings of inadequacy, being discriminated against
BMI
It is a measure of body weight relative to height Correlates significantly with body fatness Helpful tool in determining something else associated with body weight health risks
is BMI on itself a diagnostic tool?
NO physical activity, blood pressure, blood glucose levels, cholesterol levels, smoker?, waist circumference, diet, family history
basal metabolism
NOT digesting food energy expended to maintain an awake, resting body Includes all the essential metabolic reactions and life- sustaining functions to keep you alive (breathing, heartbeat, circulation, nerve impulses, hormone secretions, maintaining an appropriate body temperature, removal of waste, and the making of new tissue)
what can trigger an eating disorder?
Sexual abuse; daily teasing & being bullied; judgmental comments by a friend, family member, or coach; bereavement; and having a disease or chronic condition
dual energy x ray absorptiometry
Uses x-rays to measure bone, fat, and fat-free mass
steps to follow to determine who would benefit from weight loss (step 2) (individual is overweight)
access for obesity related conditions that increase health risks --> if obese go straight to weight loss -high blood pressure, abnormal blood lipids, blood glucose, sleep apnea, inactive, cigarettes, family history
drawbacks of skin fold tests
administered by untrained technician assumption that this area of fat represents total fat
lean body mass decreases and body fat increases with ____
age
energy balance
amount of energy in vs out consume more than expend? gain weight problem in US
appetite vs hunger
appetite (external cues such as sight, smell, and taste of food stimulates endorphins) -other: hormones, food preferences, drugs, eating habits hunger (internal physiological signals) -empty stomach/low nutrients in blood -usually sets in 4-6 hours after eating
estimated energy requirements (EER)
average energy intake values predicted to maintain body weight in a healthy individual as set forth by the DRI committee is called
managing body weight
balance intake/expenditure for some its weight management= avoiding gains in weight others its obtain a weight that minimizes health risk= dietary and lifestyle changes may be necessary
assessing weight in 2-20 YOs
based on age and gender Calculate BMI & use the Body Mass Index-for-Age Gender Specific -this contains series of lines indicating percentiles -ex: 5th percentile means only 5% would have lower BMI
balancing energy intake with energy expenditure
be aware of foods/beverages consumed energy comes from types/amounts of food 4cal/g (protein/CHO) 9cal/g (fat) 7cal/g (alcohol)
overweight
being too heavy for ones height due to excess body fat 25-29.9 kg/m2
occurrences of eating disorders
can occur in all people girls are two and a half times greater typically begins in adolescence when development is occurring rapidly
obesity genes
code for proteins involved in regulation of body fat if abnormal there will be extra fat affect -how much you eat -how much energy you expend -how fat is stored in your body
how does weight gain happen
consume more energy than expend so energy is stored -Small amount of CHO is stored as glycogen in liver and skeletal muscle -Most of the excess energy-yielding nutrients are stored as TGs in fat Enlargement of fat cells and formation of new fat cells weight gain and increased body fat
steps to follow to determine who would benefit from weight loss (step 1)
determine BMI/measure circumference of waist -healthy BMI? weight loss is not necessary (maintain) -unhealthy BMI? weight loss is necessary
diet vs. fad diets
diets that are quick gain weight back right away unless you continue to consume less food
fasting/starvation and weight loss
does not work lowers BMR so fewer calories expended
what can delay satiety
eating too fast takes 20 minutes
basal metabolic rate
energy expended for basal metabolism
genetics may also have a role in keeping your body weight constant for long periods, regardless of
energy intakes and expenditures
modifying behavior (weight loss)
establishing a pattern of food intake & exercise that helps with maintaining a healthy weight identifying behaviors that led to weight gain/replace them with ones that promote weight loss/weight maintenance
genetics and obesity
even greater risk of being obese +influence of lifestyle = huge risk
increasing physical activity (weight loss)
expend 200 calories (5 days a week) + calories = wt loss of 1 lb in about 3 weeks increased energy expenditure, muscle mass, and BMR stress reliever
subcutaneous fat
fat stored directly under the skin (pear)
visceral fat
fat stored within the abdominal cavity in association with the internal abdominal organs (apple) more metabolically active higher risk of heart disease, high blood pressure, stroke, diabetes, and breast cancer
satiety
feeling of fullness and satisfaction caused by food consumption that eliminates desire to eat
EER accounts for
gender age height weight activity level (sedentary, low active, active, and very active) life stage (ex. growth)
what plays a major role in determining body weight
genes
factors that determine where fat is deposited
genes 1. positive association between visceral fat and being a man, menopausal women, Caucasian or asian, tobacco user, drinker, or stressed 2. negative relationship between visceral fat and physical activity
overall trend of obesity
getting increasingly worse now considered an epidemic (occurrence of a health related event in excess of normal expectancy)
hormones that monitor body fatness
ghrelin, peptide YY, and leptin
physiological complications with too much fat
high blood pressure, heart disease, respiratory problems, cancer
Ghrelin
hormone made by stomach that makes you hungry at your meal time regardless of the last time you ate
drawbacks of ignoring fullness
increase body weight
taller person and BMR
increased BMR
waist circumference
indicative of visceral fat BMI+waist circumference estimate health risks with excess body fat
calculation for BMI
kg/m^2
obese individuals have high levels of
leptin bc it prevents weight loss
lean body mass
mass attributed to nonfat body components such as bone, muscle, & internal organs
men or women have higher BMR
men bc more lean mass
waist circumference cutoffs
men: BMI of 25-34.9 & less than 40 in. women: BMI of 25-34.9 and less than 35 in.
how does weight loss happen
moderate reduction in calories reduction of energy caused use of stored energy: (glycogen→ glucose → ATP) (TGs (in fat cells) → fatty acids & glycerol → ATP) (proteins amino acids can make ATP and glucose)
how can you avoid obesity regardless of being predisposed or not?
monitor the diet (MyPlate and DGA) exercise regularly
other health concerns with visceral fat
more can be released into blood stream may attach to LDLs which are associated with arterial plaque/heart disease
muscle and BMR
more muscle = higher BMR
does being overweight technically mean you are unhealthy?
no if someone is overweight but eats health/exercises they are more well off
decreasing energy intakes (weight loss)
nutrient dense foods multivitamin/minerals with intakes under 1200 cal medical supervision with diets under 800 cal
energy expenditure
total amount of energy used by the body each day -3 components: basal metabolism -energy needed for physical activity -energy needed to process the food we eat (thermic effect of food)
eating disorder
physiological illness characterized by specific abnormal eating behaviors, often intended to control weight
which type of obese people are at greater risk
ppl who have been obese longer/have more body fat
medical goal for weight loss
reduce health risks losing 5-15% of body weight within 6 months should be gradual! -1/2 to 2 lbs a week (500 cal reduction a day) calories shouldn't be severely restricted
peptide YY
released in small intestine released in proportion to number of calories consumed reduce appetite
subcutaneous and blood stream
released slower, hence contributing less to blood lipid levels
yoyo diet
repeated cycle of weight loss/gain
3500 calorie reduction?
weight loss of 1 lb of body fat
leptin
secreted by adipocytes in proportion to fatness regulate energy intake and expenditure suppress the appetite and hopefully food intakes gains in body fat stimulate leptin production and decrease food consumption loss of body fat means leptin is suppressed and appetite is increased better at preventing WEIGHT LOSS
level at which body fat or body weight seems to resist change despite changes in energy intake or output is called
set point -determined by genes -regulate short term changes food intake/activity -regulate long term changes in stored body fat
what affects the amount of energy used during physical activity
size of individual strenuous of activity length of activity
anthropometric measurements
skinfold or fatfold tests and waist circumference
body weight
weight of body fat and lean body mass
air displacement
technique to assess body composition by calculating the body volume from the air replaced by an individual sitting inside a small chamber BOD POD
bioelectrical impedance
technique to assess body composition by running a weak electrical current through the body
when waist circumference is less than the cut off points..
they still have some risk associated with being overweight, but the risk is higher when the waist circumference is above the cutoff points
BMI does not equal percent body fat: T or F?
true indicator of healthfulness of body weight does not reveal body fat nor where fat is located cannot classify someone of being obese nor determine health risk
skinfold tests
used to measure thickness of fat under skin at different locations caliper does this
why do some people gain weight more readily than other?
variation of genes and how they interact (metabolism, food intakes, fat storage, activity) inherited thrifty genes (originally survival genes that preserve fat) inherited tendency to expend less energy
more likely to be obese if
your parents are obese environmental or genetic