chapter 7 notes - energy balance and weight management

energy out: REE (resting energy expenditure)

measured and expressed as RNR: Rising Metabolic Rate

why are we eating more

- portion sizes have increased - appetite vs. hunger - portion distortion (effects of portion size on food intake) - concept of "Eating in units": larger portions --> great intake of calories.

energy in: Fuels for metabolism

- the digestive system (the transport systems) send the cells glucose, amino acids, glycerol, and fatty acids

assessing body composition: - underwater weighing

- Involves weighing a person out of water then under water. - Underwater weighing: Water is displaced by body mass. This difference is equivalent to body volume and the weight out of water over the volume is body density. - Use equations to calculate fat-free mass - Air displacement in a BOD POD is now used.

gastric sleeve

- Removal of part of the stomach - Most common type of bariatric surgery performed in LA - Not reversible - Better long term results - Just restricts food intake, removal of part of the stomach (70-80%)

gastric bypass

- Restricts the size of the stomach and bypasses part of the small intestine. Smaller stomach limits food intake, shorter intestine reduces absorption - higher risk of surgical procedure (more invasive)... higher cost - higher risk for post surgery complications (more malabsorption after procedure) - difficult to reverse - Supplements for life. - Significant weight loss is usually achieved 18-24 months after weight loss surgery

set point theory of weight control

- an individual's metabolism will adjust itself to maintain a weight at which it is comfortable - +/- 10% from the midpoint

the nervous system also plays a role in body weight regulation

- command center = hypothalamus - plays a key role in integrating signals related to food intake, satiety, and adiposity.

an ideal weight loss program

- tips for losing weight and fat - watching your serving size - cut down on high kcalories foods

aging men

With aging, lean body mass decreases; between the ages of 20 and 60, body fat typically doubles even if the body weight remains the same. This occurs regardless of energy intake. Some of this loss of lean body mass can be prevented by strength training

gastric banding

- Adjustable band around stomach (Least invasive, Less surgical risk and reversible (but return visits to MD for adjustment), Greater opportunity for weight re-gain (not as effective), some eat lots of small meals and gain the weight back) - Holds about 1 oz. this band can be tightened or loosened over time to change the size of the opening (Just restricts food intake)

what is your BMI?

- BMI = weight in kg/(height in m)2 - Healthy body weight is defined as BMI of 18.5-24.9 kg/m2 - Underweight = less than 18.5 kg/m2 - Overweight = 25-29.9kg/m2 - Obese = 30 kg/m2 or greater

assessing body composition: - Bioelectric impedance analysis (BIA)

- Based on resistance of flow of a low level of electricity, but is affected by the amount of water in the body so can be affected by many factors - food in the GI tract, exercise, age - Estimates body fat by directing a low energy electrical current htrough the body.

assessing body composition: - radiologic methods

- Dual-energy x-ray absorptiometry (DXA): use low energy x-rays to determine bone, muscle, fat tissue. - Computed tomography (CT) scans are used to determine abdominal visceral fat.

how excess body fat affects health

- Having too much body fat increases a persons risk of developing a host of chronic health problms, including heart disease, high blood pressure, stroke, high blood cholesterol, diabetes, gallbladder disease (increase in gallstone formation), arthritis, sleep disorder, respiratory problems, and certain cancers. - Heart disease, stroke, and diabetes.

bariatric surgery

- Individuals who qualify for this type of procedure - Individuals in whom risk of dying from obesity and its complications is great - BMI > 40 - Sometimes recommended with BMIs of 35 - Each case individually evaluated - When people have tried other method and failed - Obesity severely limits quality of life - Success requires lifelong commitment including attention to diet and physical activity

intensity of different activities

- It is assumed that we spend about 2.5 hours per day in these types of activities: gardening (no lifting), watering plants, raking leaves, mowing the law, household tasks, loading/unloading the car, walking the dog - Moderate-intensity activities: Activities that expend about 210-420 kcal/hr. for a 154 lb. individuals: bicycling, dancing, yard work, golf, hiking, swimming, walking, water aerobics, weight lifting. - Vigorous intensity activities: Activities that expend more than 420 kcal/hr. for a 154 lb. person: aerobics, basketball, bicycling, climbing, jogging, jumping rope, swimming, tennis.

Obesity around the world

- Louisiana 20-24% in 2000 and greater than or equal to 30% in 2010. - actual causes of death in the United States, 2000: tobacco, diet/physical health, alcohol, microbial agents, toxicity agents, motor vehicle crashes, firearms, sexual behavior, illicit drugs

conclusion

- Overweight/obesity is a major nutrition-related public health crisis. - Food contains energy and the body uses this fuel to produce ATP which supports body functions. - Various methods are used to determine energy needs and body composition. - Body energy regulation is complicated and body weight set point is difficult to change

assessing body composition: - skinfold thickness

- Skinfold thickness analysis: a skilled person measures the thickness of fat under the skin at several sites around the body. - It is less accurate in obese and elderly subjects

energy in: calorie and kilocalorie

- a calorie is a measure of the amount of energy that is supplied to or expended by the body. - a calorie = the amount of energy (heat) required to raise the temperature of 1 gram of water 1 degree celsius - kilocalorie = 1000 calories

DRI estimated energy requirement

- an EER is the amount of energy predicted to maintain energy balance in a healthy person in various categories. - it is important to know the person;s activity level to determine if its sedentary, low active, active, or very active - one may also keep a journal of activity for a couple of weeks and calculate the kcal consumed food lists

managing America's weight - calories

- balance your intake and output (known your calorie needs and monitor what you eat, weigh yourself once a week, add extra exercise, count the calories in alcoholic beverages) - cut down on calories

how is energy expenditure measured? 2. indirect calorimetry

- because oxygen is used and carbon dioxide is given off as a result of the energy-using metabolic processes energy needs can be "indirectly" estimated by assessing these two gases. - during the test: subjects must breathe into a mouthpiece, mask, or ventilated hood - oxygen use and carbon dioxide production is measured

energy in: energy content of foods

- carbohydrates (4 kcal) - protein (4kcal) - fat (9 kcal) - alcohol (7kcal) - remember: vitamins, minerals, and water do not provide energy for your body.

what is the relationship of body weight and health: health risks associated with excess body weight: - cardiovascular disease - type 2 diabetes - respiratory problems - other: - gallbladder disease - osteoporosis - menstrual irregularities - cancer risk - sedentary lifestyle

- cardiovascular disease more common: increased blood pressure, triglyceride levels, and LDL cholesterol. HDL cholesterol decreases - type 2 diabetes increases: increase in fasting blood sugar. 80% of people with the 2 diabetes are obese. Incidence increases as much as 30 fold with a BMI of >35. - respiratory problems more common. Sleep apnea increases. asthma worsens because the workload of muscles used for breathing increases. - gallbladder disease is more common - osteoarthritis and degenerative joint disease increases - menstrual irregularities are increased in overweight women. - cancer risk is higher in overweight people: women (endometrium, breast, cervix, and ovaries). men (colorectal and prostate) - a sedentary lifestyle further increases risk: obese individuals whoa re inactive have higher risks of illness and death. Inactivity increases the likelihood of developing diabetes and heart disease

definition of obesity

- condition of excessive fat, either generalized or local - it is possible to be overweight but not over-eat, and over-eat but not overweight.

overweight and obesity statistics

- data from 1999 --> 2010 reflect 68% of US. adults are overweight or obese. - a dramatic increase - same trend seen in the U.S. is seen worldwide - higher average incidence in African American and Hispanic American populations - concern with increased risk of chronic disease such as diabetes, heart disease, and cancer. - medical care costs of obesity in U.S. estimate ~ 147 billion

managing America's weight - physical activites

- don't get too hungry (eat breakfast, fill up on high-fiber foods, increase your serving of low-calorie vegetables, choose nutrient dense snacks) - increase activity (bike ride, bowling, take a walk, play tennis, increase the distance you walk) - behavior modification 1. Identify the antecedent: watching TV 2. Behavior: Recognize the behavior: overeating high-calorie snacks in front of the TV 3. Consequences: see them: guilt about overeating and weight gain 4. Modified behavior: take a small portion of a healthy snack with you to watch TV 5. Enjoy the new consequences: improved self-esteem and successful weight management. - losing weight and fat (lifestyle change hasn't worked too well for the majority of people. if one is dedicated to doing it right, lifestyle changes do work - reducing energy intake and increasing energy expenditure also lose the weight slowly)

ENERGY IN (calories consumed in food) - weight management terms

- energy balance occurs when energy consumed = energy expenditure - the chemical energy found in food, which the body uses to do its work, is measured in kilocalories (kcal) in U.S. - energy is not synonymous with how you feel. - energy = the capacity to do work - overweight - too heavy for one's height or having a BMI of 25-29 - obesity is characterized by excess body fat or a BMI is greater than or equal to 30.

energy in vs. energy out

- energy expenditure: activity reduces the risk of obesity - people are eating more and exercising less - relationship between obesity and screen time.

who should lose weight

- first measure BMI and waist circumference - overweight: is there at least two obesity-related risk factors present? if not, weight loss isn't necessary. if yes, weight loss is recommended. - obese: BMI is greater than or equal to 30 - weight loss recommended. - guidelines for children and adolescents - pregnancy and lactation - older adults: reserve vs. effect of excess weight on ADLs/

methods to reduce energy intake

- food exchanges, prepared meals and drinks, very low calorie diets, low fat diets, low carb diets

body energy stores

- for normal function, the body's cells need a steady supply of energy. - right after a meal and for a couple of hours following: most tissues use glucose from the diet for energy (if rating typical carbohydrate-containing meals) - in between meals: - glycogen is broken down to provide blood glucose and to replenish citric acid cycle compounds - stored fat is broken down to provide energy for most tissue and some protein is used to make glucose.

how location of body fat affects health risks: body composition

- genetics can affect the amount of visceral fat. (african American men store less abdominal fat than what men of the same age). - after menopause, women become more like men - demonstrating effects of hormones - stress, tobacco use, alcohol consumption increase abdominal visceral fat but physical activity decreases visceral abdominal fat.

peptide hormones for short term

- ghrelin (hunger hormone): produced by the cells in the stomach, increases appetite and food intake - cholecystokinin (CCK): produced by upper gut. suppresses food intake - peptide YY (PYY): produced by lower gut. suppresses food intake - glucagon-like peptide 1 (GLP-1): produced by cells in the lower gut. May decrease food intake, may increase metabolic rate.

hormones play a role

- ghrelin is a hunger hormone and is released primarily by the stomach - leptin is produced by white adipose tissue and signals to the brain how much body fat is present. - glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) are released by the terminal ileum, and large intestine and are satiety hormones

storing excess kcal as triglycerides

- glucose and ketogenic amino acids are converted to body fat when the diet is high in carbohydrate or protein and is in positive energy balance. - most energy efficient way to store body fat - dietary fat to body fat.

stored energy in the body

- glycogen: primarily stored in the liver and muscle - 1400 kcal - glucose or lipid: primarily stored in the body fluids - 100 kcal - triglyceride: primarily stored in adipose tissue - 115,000 kcal - protein: primarily stored in muscle - 25,000 kcal - fat cells = adipocytes - adipocytes also increase in size to store more fat if necessary

weight loss goals and guidelines

- goal: to reduce the health risks associated with overweight and obesity. - weight cycling - one pound = 3500 kcal - program to include: reduction of energy intake (role of nutrient density and changing eating patterns), increased physical activity (benefits/recommendations), behavior change

how is energy expenditure measured? 1. direct calorimetry

- heat is directly related to energy expenditure because all metabolism in body results in some heat production - direct calorimetry measures the amount of heat given off by a person;s body when he/she is in an insulated chamber

hunger, appetite, satiation, and satiety

- hunger is the true physiological need to eat. internal cues that prompt us to eat. - appetite is desire to consume a specific food independent of hunger - satiation: refers to reduced hunger and faster termination of eating (foods that are readily overeaten are usually highly palatable and have high energy density - satiety: refers to a longer term feeling of fullness and satisfaction following the termination of a meal. it is used to measure motivational rating with participants indicating their levels or fullness or desire to eat at a given point in time.

energy out: NEAT (non-exercise activity thermogenesis)

- includes energy expended for unintentional exercise - fidgeting also fits into this category

energy out: TEF (thermic effect of food) or diet induced thermogenesis

- includes the energy needed to digest food and to absorb, metabolize, store nutrients - larger meals result in a higher TEF - macronutrients don't similarly impact TEF - a general mixed meal = TEF ~10% of energy consumed: --- TEF for FAT = 2-3% of energy consumed --- TEF for CHO = 6-8% --- TEF for PRO = 15-30%

weight loss drugs and supplements

- indications for use: BMI > 30 or BMI greater than or = to 27 + obesity related risk factors or disease. - 2 basic types of weight loss medications: -- promote a decrease in food intake: (phentermine (Adipex = brand name) and amphetamine and phentermine (Onexa = brand name)) -- promote reduction of energy intake by reducing fat absorption (Orlistat (Xenical = brand name) and Alli (OTC version)) - it is easier to eat less when someone else decides what you're having and puts appropriate portions of that food in front of you. (expensive, no long term practicality, no teaching food-selection skills for long-term change)

why some people gain weight easily

- inheriting a thrifty metabolism (survive well when food is scarce, but develop obesity when food is plentiful) - lack of adaptive thermogenesis, producing heat when overeat (changes in energy expenditure induced by factors such as food intake - i.e. starvation) - lack of futile cycling (metabolic process that wastes ATP - have less brown adipose tissue - a type of adipose tissue that keeps us warm when cold by generating heat - wasting energy. -- tissue contains more mitochondria than white adipose tissue -- mitochondria uncoupled form electron transport chain - energy lost as heat instead of used as ATP -- found in infants -- new evidence may also be present in adults in varying levels -- it may come down to lack of NEAT - lean people seem to fidget more and be more restless than overweight and obese people

what determines body size and shape? - genes vs. environment

- is there only one gene associated with body weight regulation? - family history and obesity - individuals with family history of obesity are 2-3 times more likely to become obese - many studies regarding gene vs. environment involved twins - based on study results (reference in text) - evidence that (75% of the variation in BMI is due to genes) (25% of the variation is due to environment) - if people who inherit genes that predispose them to being overweight carefully plan their food intake and exercise regularly, they can maintain a healthy weight. - is it possible for someone with no genetic tendency toward obesity to become overweight or obese? (yes, if they consume a high-calorie diet and get little exercise

suggestions for weight gain: evaluating weight loss programs - a fad diet

- limits food selections, rapid weight loss, weight loss without the need to exercise - may require a rigid menu, purchase of special food, weight loss patches, expensive supplements - not recommended changes in activity and eating habits. provides no support - makes outlandish and unscientific claims, relies on testimonials

bariatric surgery

- many scientists have given up on lifestyle changes as solutions to the obesity crisis and have turned to pharmaceutical drugs and surgery. - however, there have not been any really effective and safe drug treatments - so scientist have been praising the effects of gastric bypass surgery

Energy out: RMR (resting metabolic rate)

- measured when there have been 5-6 hours without food and exercise and tends to be 10-20% higher than BMR

What is the relationship of body weight and health: health consequences of obesity

- mortality risk begins to increase with BMIs > 25. - this increase is modest until a BMI > 30. - for persons with a BMI >30 all causes of mortality are generally increased by 50-100% above persons with a BMI of 20-25.

energy homeostasis (zero energy balance)

- most adults maintain a fairly constant body weight and this is in energy homeostasis or zero energy balance. - the energy stored with consumption of food is used in between meals and then is replenished with the next meal and on and on.

how location of body fat affects health risks

- people with too little fat don't have the energy reserves for illness - being too lean can lead to greater mortality than being normal weight - often times underweight is due to self-starvation as a result of having an eating disorder. - lean tissue or lean body mass or fat free mass: includes bones, muscle, liver, nerve: anything besides fat. - fat or adipose tissue: includes fat under the skin (subcutaneous fat) and around the internal organs (visceral fat). Visceral fat is found primarily in the abdominal area. - a healthy level of body fat to body weight for a young adult women is 21-32%. for a young adult male, it is 8-19%. - body fat increases with pregnancy. - as we age beyond ~40 years of age, we lose lean mass and gain body fat. - this may be prevented to some extent with strength training.

excess body fat and disease risk

- psychiatric and psychosocial problems such as depression and low self-esteem. - respiratory problems such as sleep apnea and asthma - increased risk for cancers of the breast, colon, uterus, esophagus, pancreas, kidney, thyroid, and gallbladder. - cardiovascular disease and risks including blood triglycerides and LDL cholesterol, low HDL cholesterol, atherosclerosis, hypertension, and stroke - gastrointestinal reflux - fatty liver - gallbladder disease and gallstones - elevated fasting blood glucose and type 2 diabetes - arthritis and gout - genealogical problems, including an abnormal menstrual cycle and infertility.

how food intake and body weight are regulated? - short term

- regulating food intake from meal to meal. Influence how often and how much we eat in a given day. - The simplest type of signal about how much food has been eaten comes from local nerves in the walls of the stomach and small intestine that sense the volume or pressure of food and send a message to the brain to either start or stop eating. Once food is consumed, the presence of nutrients in the GI tract triggers the release of gastrointestinal peptide hormones that interact with the nervous system to affect hunger or satiety. - Once nutrients have been absorbed, circulating levels of nutrients (glucose, amino acids, ketones, and fatty acids) are monitored by the brain and may trigger signals to eat or not. - there are many types of peptide hormones that regulate food intake: ghrelin, cholecystokinin, peptide YY, glucagon-like peptide 1

what food intake and body weight are regulated? - long term

- regulating the amount of body fat. influence the weight management over months and years - short term regulators of energy balance affect the size and timing of individual meals, but if a change in food intake is sustained over a long period, it can affect long term energy balance, and hence, body weight and fatness. - regulating amounts of body fat - secrete by fat cells (leptin, adipopectin, leptin regulation, insulin)

physical activity

- represents the metabolic cost of external work or muscular activity - includes energy needed for planned exercise as well as for activities of daily life. - includes energy for unintentional exercise (non-exercise activity thermogenesis or NEAT)

energy expenditure - sedentary person - physically active person - very active person

- sedentary: (2500 calories/day) ex:(a student who spends most of his day studying and sitting in class, expends only about 15% of his total energy expenditure for physical activity - physically active: (3000 calories/day) ex:(a person who works in an active job, or includes at least an hour of exercise per day, will expend 30% or more of his total energy). - very active person: (3500 kcal/day) ex: (such as a college athlete who trains 5-6 hours a day, may expend more energy in activity than for basal metabolism).

why are we getting fatter? American are eating more

- supermarket, fast-food restaurants,and convenience marts make affordable for really available to the population 24 hours a day. - we are constantly bombarded with cues to eat: advertisement, food courts with sights and smells of fatty, high calorie foods and vending machines. - portion sizes have increased - Americans are also moving less. - facts: eating is voluntary/food is accessible; eating is necessary/cannot "quit." - problem/etiology/ solution: all are complicated

ENERGY OUT: calories used by the body - TEE (total energy expenditure)

- the sum of the energy used for: - basal energy (~60-75% of TEE) - physical activity (~15-30% of TEE) - processing food (~10% of TEE) - depositing new tissue (growth and pregnancy) - producing milk (breast feeding) - heat production in cold environments

suggestions for weight gain: evaluating weight loss programs - a healthy diet

- variety of foods - reasonable weight loss of 0.5-2 pounds per week: 1200 kcal/day - physical activity, flexible, not costly supplements - promotes change in behavior. teaches new eating habits. provides social support

fasting vs. feasting

- weight gain: energy in > energy out - weight loss: energy in < energy out

energy in: determining the amount of energy in food

- when dried food is combusted inside the chamber of a bomb calorimeter, the rise in temperature of the surrounding water can be used to determine the energy content of the food.

body hierarchy

- when weight loss occurs, body energy stores are used. - when weight gain occurs, body energy stores are built.

how to calculate EER

1. Find your weight in kilograms and your height in meters - weight in kg = weight in pounds/2.2 lbs/kg - height in meters = height in inches/ 0.0254in/m 2. Estimate the amount of physical activity you get per day. Find the PA value for someone your age, gender, and activity level 3. Choose the appropriate EER prediction equation below and calculate your EER

energy in: coverting food energy into ATP

1. Glycolysis breaks glucose in half to yield two pyruvate molecules that are converted to acetyl CoA. 2. Beta oxidation breaks fatty acids into two-carbon units that form acetyl CoA 3. After deamination, amino acids can break down to form acetyl-CoA, pyruvate, and other intermediate 4. The acetyl-CoA from glucose, fatty acid, and amino acid breakdown can enter the citric acid cycle 5. The electrons released are passed to the electron transport chain, and their energy is used to convert ADP to ATP

Energy out: basal metabolism: 1. Basal energy expenditure (BEE) 2. basal metabolic rate (BMR)

1. basal energy expenditure: - energy expended to maintain an awake, resting body that is not digesting food - BEE fuels: breathing, circulating blood, regulating body temperature, synthesizing tissues, removing waste products, sending nerve signals. 2. basal metabolic rate (BMR): - rate at which energy is expended to meet these basic functions often expressed in kilocalories per hour - affected by: body weight and height (lean body mass - nonfat body component), gender (higher for men than women), growth rate (higher during rapid growth), age (lower in older reflecting drop in lean body mass), fever and stress, fasting and constant malnutrition. - measuring basal metabolism: when measuring basal metabolism residual energy use from activity and digestion and absorption of nutrients is minimized (morning in warm room before subject rises and minimum of 12 hours without activity or food intake) - because of the restrictions in measuring BMR.

energy in: estimating the energy content of the food

1. determine the number of grams of carbohydrate, protein, fat, and alcohol in a food or meal 2. calculate the energy provided by each (grams of carbs, pro, fat, alcohol x 4,4,9,7kcal/g = calories from ___). 3. calculate the total energy = kcal from carbohydrate + kcal from protein + kcal from fat + kcal from alcohol Energy descriptors on food labels: • Note that there are 2.5 servings in the bottle • So 2.5 x 100 = 250 kilocalories • Or 25 g of sugar x 2.5 = 62.5 g sugar in the bottle x 4 kilocalories/g = 250 kcalories

types of fat cells: 1. leptin 2. adipopectin 3. leptin regulation 4. insulin

1. leptin: increased when fat stores are increased, acts on the hypothalamus (interacts with many other peptides in the brain), production may be related to levels of circulating insulin, decreases food intake, increases energy expenditure 2. adipopection: increased when fat stores are decreased, stimulates food intake, increases insulin sensitivity, decreases sensitivity 3. leptin-regulation: better at preventing weight loss than preventing excessive weight gain. hormones produced by fat cells that is able to tell the brain the amount of fat stored. Some people don't make leptin or a functional receptor for leptin in the brain and both are obese. these inidivudals become normal weight with leptin treatment - however, most overweight and obese have plenty of leptin and are resistant to leptin. Leptin was once thought to be the magic bullet for obesity treatment 4. insulin: stimulates glucose uptake by cells. secreted by beta cells of the pancreas - resistance = type 2 diabetes - deficiency = type 1 diabetes

assessing body composition: - dilution methods

A water-soluble isotope can be ingested or injected into the bloodstream nd allowed to mix with the water through the body. The diluted can be used to calculate the amount of lean tissue in the body, and body fat then can be calculated.

Body Mass Index: calculating BMI

Calculating BMI: 1. Convert weight in lbs. to kg: Weight in lbs. divided by 2.2 = weight in kg. 2. Convert height in inches to cm: Height in inches x 2.54 = height in cm. 3. Convert height in cm to height in m: Height in cm / 100 = height in m. 4. Find height in meters squared 5. Divide weight in kg by height in meters squared = BMI

why are we getting fatter? why are more people overweight and obese?

Positive energy balance is due to: 1. increased calorie intake - (larger portion sizes, highly palatable, energy-dense foods, increased kilocalories due to more fat and sugar, people tend to eat in "units" - regardless of size) 2. reduced physical activity - (more mechanized lifestyle, more sedentary jobs)

Obese and muscular men

both of these men have a BMI of 33, but only the obese man has excess body fat. The high body weight of the muscular man is due to his large muscle mass. The amount of body fat he has, and hence his disease risk, are low .

national institute of health guidelines

classify individuals with BMI of 25-29 as overweight and with BMI of 30 or greater as obese

energy use

there a hierarchy of nutrient use for energy based on the ability to store the energy macronutrient: - alcohol (no storage) - protein (amino acids) (no storage) - synthesize proteins and then used for energy. any excess is then broken down to provide energy because there is no mechanism for storing them as amino acids or proteins - carbohydrate (limited ability to store as glycogen) - used for energy, maintaining blood glucose, and glycogen stores. Once glycogen stores are full, the remaining carbohydrate is oxidized for energy. - fat (within reason - unlimited, as triglycerides) - used for energy in between meals.

how food intake and body weight are regulated?

what we eat and how much we exercise vary from day to day but body weight tends to remain relatively constant for long periods. - set point: resists weight change - satiety: the feeling of fullness and satisfaction

how is energy expenditure measured? 3. doubly-labeled water

with this test: - an individual is given heavier isotopes of oxygen and hydrogen - the individual is not confined and carries no equipment - through calculations, the CO2 is produced and total energy expenditure can be estimated. - the particular component of energy expenditure (basal kcal needs, physical activity or thermic effect of food), cannot be determined but will be able to estimate total energy expenditure