Ch 7: Energy Balance and Weight Control - unfinished

calculate body mass index

(Metric): BMI = kg/m^2 (English): BMI = (lb/in^2)*703

common methods to assess body composition

-underwater weighing (aka hydrostatic weighing or hydrodensitometry) -air displacement (BodPod) -Skinfold thickness -Bioelectrical impedance (BIA) -Dual energy x-ray absorptiometry (DEXA): most accurate but is expensive and impractical for every day use

kcal deficit that is typically required to lose 1 lb/week

1 lb of weight loss = 3500 kcal in theory reducing kcal intake by ~500 kcal per day below energy needs results in weight loss of ~1 lb/week in reality, weight loss is not linear other factors besides math equation ^ come into play. -as loose weight energy needs decrease slightly -hormonal changes affect metabolic rate and appetite -unconscious adjustments in physical activity -it take ~3 yrs to fully realize the effect of kcal deficit

__ to __ lbs per week is a safe and sustainable rate of weight loss

1 to 2 lbs per week - when weight is lost, it is a combination of lean and fat mass; the goal is to maximise fat loss and minimise the loss of lean tissue - Rapid weight loss (> 2 lbs/week) is likely due to loss of water; not sustainable

3 key elements of a sound weight loss program

1. control calorie intake 2. control problem behaviors 3. preform regular physical activities

Normal (healthy) weight according to BMI

18.5-24.9

Overweight according to BMI

25-29.9

Underweight according to BMI

< 18.5

Obese according to BMI

> 30

How does ratio of fat to lean tissue affect fat storage

A high ratio of fat mass to lean body mass is correlated with weight gain

How does basal metabolism affect fat storage

A low BMR due to factors such as thyroid problems or energy restrictions is linked to weight gain

How does childbearing affect fat storage

A pattern of weight gain during the childbearing years can occur to support fetus. Fat stored during pregnancy to support lactation may not be lost in women who do not breastfeed.

BMI is a convenient screening tool for overweight and obesity but its does not directly assess body composition

BMI is a simple ratio of weight to height Body composition refers to the percent of the body that is lean versus fat

Is body weight determined by nature or nurture?

BOTH nature i.e. genetics nurture i.e. behaviors

How does fat uptake by adipose tissue affect fat storage

Efficiency of fat storage is high in some obese individuals and may even increase with weight loss

How does Dietary consumption affect fat storage

Excess calorie intake from saturated fat, alcohol, and calorie-dense foods and beverages contribute to obesity

How does Gender affect fat storage

Females have more fat mass than males due to less lean body mass and reduced surface area

How does genetic predisiposition affect fat storage

Genetic factors may affect energy expenditure, deposition of adipose tissue or lean tissue, and the relative proportion of fat and carbohydrate used by the body.

How does Menopause affect fat storage

Hormonal changes result in result in increased abdominal fat deposition

How does Ethnicity affect fat storage

In some groups, higher body weight may be more socially acceptable, which may promote overeating

How does certain medications affect fat storage

Increased hunger/appetite can be a side effect of many medications

How does social and behavioral factors affect fat storage

Obesity is associated with socioeconomic status; familial conditions; social networks; lifestyles; binge eating; availability of inexpensive, "supersized" high-fat food; patterns of leisure activities; increased screen time; smoking cessation; excessive alcohol intake and meals eaten away from home.

How does Energy Balance affect fat storage

Over a long period, dietary patterns consistent with positive energy balance promote storage of excess body fat

How does region of residence affect fat storage?

Regional environmental and lifestyle differences, such as high-fat diets and sedentary lifestyles, especially in the South and Midwest, lead to high rates of obesity

How does physical activity affect fat storage

Sedentary behavior leads to positive energy balance and promotes body fat storage

skin disorders associates with excess body fat

accumulation and trapping of moisture and microorganisms in tissue folds

factors that are taken into account when determining EER

age male or female height weight activity level

calorie (w/ lower case c)

amount of heat energy required to raise the temperature of 1 gram of water by 1 degree Celsius

how does EER vary by age, gender, and activity level?

as age increases (during adulthood), EER declines Men tend to have higher EER than women EER increases as physical activity increases

components of energy expenditure

basal metabolism physical activity thermic effect of food adaptive thermogenesis

components of energy intake (from foods and beverages)

carbohydrate fat protein alcohol

direct calorimetry

determine energy expenditure by measuring heat released from the body

indirect calorimety

determine energy expenditure by measuring oxygen uptake and carbon dioxide output

shorter stature associated with excess body fat

earlier onset of puberty

negative energy balance

energy intake (cal in) < energy output (cal out), decrease weight change

positive energy balance

energy intake (cal in) > energy output (cal out), increase weight change

energy balance

energy intake (cal in)= energy output (cal out), no weight change (equilibrium)

thermic effect of food

energy needed to digest, absorb, and metabolize nutrients; accounts for 5% to 10% of total energy expenditure

adaptive thermogenesis

energy spent on nonvoluntary activities that maintain body temperature; accounts for < 5% of total energy expenditure (negligible) e.g., fidgeting and shivering

type 2 diabetes associated with excess body fat

enlarged adipose cells are insulin resistant

EER equations

estimated energy requirement - energy needs are not typically measured but are usually predicted by vast selection of these equations

How does age affect fat storage

excess body fat is more common in adults and middle-age individuals due to loss of lean body mass and reduction in physical activity

liver damage and eventual liver failure complications associated with excess body fat

excess fat accumulation in the liver chokes off blood supply to the liver which can lead to cirrhosis

reduced physical agility complications associated with excess body fat

excess weight impairs mobility

pulmonary disease and sleep disorders associated with excess body fat

excess weight stresses the lungs and pharynx

vision problems complications associated with excess body fat

higher rates of cataracts and other disorders

which part of the body closely regulates and monitors body fat?

hypothalamus

physical activity

includes activities of daily living and planned exercise; accounts for 15% to 30% of total energy expenditure

cardiovascular disease associated with excess body fat

increased LDL and triglycerides and reduced HDL promote atherosclerosis; increase blood clotting; increased inflammation; irregular heart rate

gallstones associated with excess body fat

increased cholesterol content of bile

bone and joint disorders associated with excess body fat

increased mechanical stress on knees, ankles, and hip joints

hypertension associated with excess body fat

increased miles of blood vessels, increased resistance to blood flow, and increased blood volume create extra work for the heart

surgical complications of excess body fat

increased need for anesthesia;l increased risk for infection

some types of cancer associated with excess body fat

increased production of estrogen, other hormones, and inflammatory compounds by adipose cells promotes tumor growth; hyperinsulinemia (secondary to insulin resistance) promotes tumor growth

pregnancy complications associated with excess body fat

increased risk for birth defects; infants may grow larger than average, leading to difficult delivery; increased risks for gestational diabetes and hypertensive disorder of pregnancy

menstrual irregularities and infertility in females complications associated with excess body fat

insulin resistance contributes to reproductive hormone imbalances, which affect ovulation; increased oxidative stress may damage eggs

kilocalorie (or Calorie, with can uppercase C)

is 1000 calories, the amount of heat energy required to raise the temperature of 1000 grams (1 kilogram) of water by 1 degree celsius

basal metabolism

minimal amount of energy required to keep a resting, awake body alive in a warm quiet environment (e.g., energy for heartbeat, breathing, brain function, etc.); accounts for 60% to 80% of total energy expenditure

erectile dysfunction and infertility in males complications associated with excess body fat

poor blood vessel function reduces blood supply to reproductive organs; oxidative stress can damage sperm; increased body temperature may inhibit sperm formation

infections complications associated with excess body fat

reduced immune function

android (upper body) obesity

refers to deposition of fat around the waist -waist circumference > 40'' for men or > 35'' for women -associated with increased risk for chronic diseases -fat is available to the liver; affects lipid and glucose metabolism -testosterone promotes android obesity (most common among men and postmenopausal women)

Gynoid (lower body) obsity

refers to deposition of fat in the buttock and thighs -not closely linked to chronic disease risk -estrogen and progesterone promote lower-body gynoid obesity (most common among premenopausal women)

How does increased hunger sensations affect fat storage

some individuals appear to have blunted satiety, which may be linked to various brain signals involved in food reward pathways

How does thermic effect of food affect fat storage

some obese individuals metabolize nutrients more efficiently, and thus expend fewer calories for digestion and absorption

prevalence of obesity among american adults

~42% of american adults