Nutrition & Diet Chapter 7 - Energy Balance And Weight Control

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65% of North American adults

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overweight

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most reliable therapy for the problem of being overweight

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-decreased caloric intake
-increased physical activity
-diet modifications

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Definition of Energy Balance

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energy input matches energy output

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energy input represents

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calories from food intake

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energy output represents

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-metabolism
-the digestion, absorption and transport of nutrients
-physical activity

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Positive Energy Balance

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energy intake is greater than energy expended
-storage of excess energy in adipose tissue
-generally results in weight gain in adults

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positive energy balance is normal and healthy

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-required in pregnancy where surplus energy supports growth of the developing fetus
-infants and children require a positive energy balance for growth and development

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Negative Energy Balance

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-energy intake is less than energy expended
-generally results in weight loss
-in adults, weight loss is a combination of lean and adipose tissue

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Maintenance of Energy Balance

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-maintenance of energy balance contributes to health and well-being in adults
-minimizes the risk of developing many common health problems
-creeping weight gain in adulthood can lead to obesity if unchecked

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-problems of energy balance can stem from lifestyle contributions

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-excess food intake
-reduced physical activity
-slower rate of metabolism

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“food hunts man” rather than man hunting for food

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-vending machines
-social gatherings
-convenient fast-serve restaurants and drive-up windows
-“super-sized” portions

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“defensive eating” is a good response

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careful and conscious food choices especially related to portion size

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determining the caloric (energy) content of foods

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bomb calorimeter

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bomb calorimeter

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-food is burned in a calorimeter chamber that is surrounded by water
-as food burns, heat is released which raises the temperature of the water
-an increase in water temperature is a reflection of energy in a food
-increase in water temperature indicates the number of kcals contained
in the food
-one kcal is the amount of heat (energy) required to increase the temperature of
one kilogram of water one degree Celsius

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carbohydrates and proteins represent

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4 kcals/gram

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lipids represent

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9 kcals/gram

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alcohol represents

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7 kcals/gram

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Basal Metabolism (Basal Metabolic Rate (BMR))

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-minimal amount of calories expended during a fasting state to keep a resting,
awake body alive in a warm, quiet environment
-maintains heartbeat, respiration by the lungs and the activity of other body organs (liver,
brain and kidney)
-accounts for 60% to 70% of the total energy use by the body (for a sedentary person)

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resting metabolism (resting metabolic rate (RMR))

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-a person not fasting or completely rested
-typically the RMR is 6% higher than the BMR

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-determination of energy needs related to basal metabolism

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-individual’s weight is converted into kilograms
-a rough estimate of BMR is 0.9 kcals/kg/hour for females and 1.0 kcals/kg/hour
for males
-take the hourly BMR times 24 hours to yield the entire BMR for one day

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some factors that increase basal metabolism

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greater lean body mass
larger body surface area per body volume (a greater surface area results in increased
heat loss)
gender (males average higher energy use; have a greater lean body mass, -body temperature (fever increases metabolic rate)
-thyroid hormones (increase metabolic rate)
-pregnancy (increases metabolic rate)
-caffeine and tobacco use (increase metabolic rate)

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lean body mass

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body weight minus fat storage weight
includes organs with high energy needs and show high
metabolic activity at rest
-skeletal muscle, kidney, brain and liver

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tobacco use

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the practice of smoking to control body weight is not recommended

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factors that decrease basal metabolism

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low calorie intake
-age (decreases metabolic rate)

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age (decreases metabolic rate)

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-as aging occurs, basal metabolism declines 1% to 2% each decade past the
age of 30

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low calorie intake

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-extreme diet regimes can lower basal metabolism 10% to 20% per day

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physical activity aids in maintaining lean body mass

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-lean body mass helps maintain high basal metabolism and aids in weight control

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Energy for Physical Activity

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-increases energy expenditure 25% to 40% beyond basal energy needs
-choosing to be active or inactive determines total calorie expenditure
-varies widely from person to person as compared to basal metabolism
-general inactivity is linked to an increased risk of obesity

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Thermic Effect of Food (TEF)

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-energy required to digest, absorb and process food nutrients
-5% to 10% of total kcals
-analagous to “sales tax”
-food composition influences TEF

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-food composition influences TEF

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-TEF value of a protein-rich meal is higher than that of a carbohydrate-rich or fat-rich
meal
-more energy is required to metabolize amino acids into fat than to convert glucose to
glycogen or transfer absorbed fat to adipose tissue
-large meals result in higher TEF values than the same amount of food eaten over many
hours

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Thermogenesis

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-increase in non-voluntary physical activity triggered by cold conditions or overeating

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-types of non-voluntary activities

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-fidgeting
-shivering when cold
-maintenance of muscle tone
-maintenance of body posture

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contribution of thermogenesis to overall calorie output

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is small

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brown adipose tissue

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specialized form of adipose tissue that participates in thermogenesis

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brown adipose tissue

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-found in small amount in infants
-brown appearance is a reflection of a rich blood flow
-contributes to thermogenesis by releasing energy into the environment as heat
-hibernating animals contain large amounts of brown adipose tissue

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-hibernating animals contain large amounts of brown adipose tissue

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allows them to generate heat needed to survive a long winter

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Direct Calorimetry

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-measures body heat released by a person
-method resembles the bomb calorimeter method for measuring the energy content of a food
-advantage
-almost all energy used by the body eventually leaves as heat
-disadvantages include expense and complexity

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Indirect Calorimetry

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-measures the amount of oygen a person uses
-the human body needs one liter of oxygen to burn 4.85 kcals of energy
-newly developed handheld instruments (Body Gem) can measure oxygen consumption

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Estimation of Energy Needs

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-based on weight, height, gender, degree of physical activity and age
-the Food and Nutrition Board has published formulas to estimate energy needs called EER
(Estimated energy Requirements)
-MyPyramid calorie guidelines

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“personal” healthy weight based on

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-weight history
-fat distribution patterns
-family history of weight-related disease
-current health status

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weight-related conditions in determining health weight

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-high blood pressure (hypertension)
-elevated LDL cholesterol
-family history of obesity, cardiovascular disease or certain forms of cancer
-body fat distribution patterns
-elevated blood glucose
-lowest weight held as an adult for one year
-clothing size
-weight maintained while dieting without being constantly hungry

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Body Mass Index (BMI)

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-current method used for calculating healthy body weight
-preferred weight-for-height standard because it is the clinical measurement most closely related to body
fat content
-calculation
-body weight (kilograms)/height2 (meters)
-convenient to use because the values apply to men and women (gender-neutral)
-healthy weight for height is a BMI between 18.5 to 24.9

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BMI > 25

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-can start leading to increased health risks
-cut-off value for overweight

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-BMI > 30

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-leads to increased health risks
-cut-off value for obesity

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-BMI > 40

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indicates severe obesity and could involve major health risks

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BMI should not be applied to the following groups

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-children and growing adolescents
-highly muscular individuals
-frail, elderly adults
-lactating and pregnant women

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BMI values for active men

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may be greater than 25 due to extra muscle mass

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BMI should only be used as a

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screening test for overweight or obesity

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major considerations when maintaining an appropriate height/weight value

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-listening to the body for hunger cues
-regularly eating a healthy diet
-remaining physically active

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-individual’s diagnosis for obesity

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-total amount of fat in the body
-the location of the body fat
-the presence of absence of weight-related medical problems

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Health Problems Associated With Excess Body Fat

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-surgical risks
-pulmonary disease and sleep disorders
-type 2 diabetes
-hypertension
-cardiovascular disease
-bone and joint disorders
-gallstones
-cancers
-skin disorders
-pregnancy risks
-reduced agility and physical ability
-infections and liver damage
-menstrual irregularities and infertility
-premature death

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desirable amounts of body fat

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-8% to 24% for men
-21% to 35% for women

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women need more body fat because

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some fat is associated with reproductive functions
(including estrogen production)

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percent body fat associated with obesity

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greater than 24% body fat for men
greater than 35% body fat for women

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-both body weight and body volume have to be known

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known to determine body fat content

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underwater weighing

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-most accurate of typical methods used to estimate body volume
-fat tissue is less dense than lean tissue (fat floats)
-the more fat tissue present, the less a person will weigh submerged

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air displacement

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-body volume is quantified by measuring space a person takes up inside a measurement
chamber (BodPod)

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water displacement

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-submerge individual in a tank of water and determine the amount of water displaced
-water displacement is least accurate

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body density =

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body weight/body volume

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% body fat =

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(495/body density) – 450

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skinfold thickness

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-common anthropometric method used to estimate total body fat
-clinicians use calipers to measure the fat layer directly under the skin
-accuracy limitations

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bioelectrical impedance

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-uses a painless low-energy electrical current
-adipose tissue resists electrical flow since it is low in electrolytes and water (as
compared to lean tissue)
-more fat means greater electrical resistance
-body fat calculators that use bioelectrical impedance are available for home use
-can provide information whether weight gain is coming from fat or muscle

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-Dual Energy X-Ray Absorptiometry (DEXA scan)

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-most accurate method for determining body fat content
-equipment is expensive and not widely available for body fat determination
-uses multiple low energy X-rays to measure body composition and bone mass/density
-assesses bone mineral density and determines the risk for osteoporosis
-allows a clinician to separate body weight into three separate components
-fat
-fat-free soft tissue
-bone minerals
-infrared light

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infrared light

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-procedure is called Near-Infrared Reactance
-assesses interactions of the infrared light beam with fat and lean tissue in the
bicep muscle of the arm
-although convenient and inexpensive, this method is not very accurate

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the location of body fat is an important predictor of

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health risks

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-upper body (android) obesity

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-fat stored primarily in the abdominal area
-associated with cardiovascular disease, hypertension and type 2 diabetes
-fat released from abdominal adipose cells goes straight to the liver
-interferes with the liver’s ability to use insulin
-negatively affects lipoprotein metabolism by the liver
-these abdominal adipose cells also make substances that increase insulin resistance,
blood clotting, blood vessel constriction and inflammation
-encouraged by alcohol intake, smoking, high glycemic load and high blood testosterone levels
-“apple on a stick” shape
-characteristic male pattern
-pot belly (large abdomen); small buttocks and thighs
-waist circumference
-greater than 40 inches in males and 35 inches in females
-if BMI > 25, health risks significantly increase

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-lower body (gynoid) obesity

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-fat storage primarily located in the buttocks and thigh area
-encouraged by the hormones estrogen and progesterone
-typical female pattern
-“pear-like” shape
-small abdomen; large buttocks and thighs
-after menopause
-blood estrogen levels decrease
-this encourages upper body fat deposition

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genes account for up to 70% of

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weight differences between people

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genes help determine

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metabolic rate, fuel use and differences in brain chemistry

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nurture (eating habits, nutrition, environment) has less to do with obesity than

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nature

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inherited specific body types

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-endomorph
-stocky build, short trunk; wide chest and hips
-short stubby bones
-round head
-ectomorph
-tall and slender; narrow chest and hips
-long, thin bones
-thin/narrow head
-mesomorph individuals will have a medium, muscular build

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-tall, thin people use more calories than shorter individuals (even while resting)

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-increased surface area results in increased basal metabolism
-tall, thin people have an easier time maintaining a healthy body weight

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-thrifty metabolism

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-enables an individual to store fat more readily
-require fewer calories to get through the day
-allows the body to use energy frugally
-tends to promote weight gain
-in past human history, when food supplies were scarce, thrifty metabolism helped protect
against starvation
-there is a general abundance of food in today’s society
-this requires high energy output and wise food choices to prevent obesity

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-set point theory

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-proposes that humans have a genetically predetermined body weight or body fat content

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some research suggests that the hypothalamus monitors

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the amount of body fat in humans

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physiological evidences supporting the set point theory

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-when calorie intake is reduced, blood concentrations of thyroid hormones decrease
(slows basal metabolism)
-as weight is lost, the calorie cost of weight bearing activity decreases
-with weight loss, the body becomes more efficient in storing fat
-increased activity of lipoprotein lipase (takes fat into cells)

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-when a person gains weight and stays at that weight for a period of time, the body tends to

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set a new set point

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-opponents of the set point theory

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-weight does not tend to stay constant through adulthood
-average person tends to gain weight slowly through adulthood
-weight can be altered if an individual is placed in a different social, emotional or
physical environment
-arguments suggest that humans settle into a particular stable weight based on their circumstances
-referred to as “a settling point”

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“Health at Every Size”

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-indirectly refers to a set point for weight by defining healthy weight as the natural weight the body adopts
-includes a healthy diet and meaningful levels of physical activity
-overall the set point is weaker in preventing weight gain than preventing weight loss

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nurture

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a reflection of eating habits, nutrition and environmental factors

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eating habits, nutrition and environmental factors of nurture

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-large portion sizes
-availability of food
-high-fat diet
-inactivity

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-husbands and wives playing a role in nurture

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-no genetic link
-may develop similar behaviors toward food
-may influence each other’s eating habits

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-adult obesity in women

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-often linked to childhood obesity
-contributing factors to female obesity
-relative inactivity
-periods of stress and boredom
-excess weight gain during pregnancy

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-adult obesity in males

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-not strongly linked to childhood
-tends to appear after the age of 30
-this pattern suggests a primary role of nurture in obesity, with less genetic influence

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-Americans of lower socioeconomic status (especially females) are more likely to be

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obese than those in upper socioeconomic groups

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factors that promote fat storage

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-lower socioeconomic status
-overweight friends and family
-a cultural/ethnic group that prefers higher body weight
-lifestyle that discourages healthy meals and adequate exercise
-excessive television viewing
-easy availability of inexpensive high-calorie food

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factors That Encourage Excess Body Fat Storage and Obesity

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-age, race and gender
-menopause
-physical activity
-positive energy balance
-diet composition
-fat metabolism and uptake
-social and behavioral factorsv

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obesity

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chronic disease

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Characteristics of a Sound Weight-Loss Plan

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control calorie intake, increase physical activity

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-control calorie intake

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-decrease calorie intake by 100 kcals/day (and increase physical activity by 100 kcals/day)
-allows a slow and steady weight loss

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-increase physical activity

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-maintenance of a healthy weight requires lifelong changes in habits
-control problem behaviors

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-appropriate weight-loss programs have the following common characteristics

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-meet nutritional needs
-can adjust to accommodate habits and tastes
-emphasize readily obtainable foods
-promote changing habits that discourage overeating
-encourage regular physical activity
-help change obesity-promoting beliefs and rally healthy social support

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-the majority of rapid weight-loss programs do not

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promote fat loss

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to lose 1 pound of fat stores per week, calorie intake must be

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decreased ~ 500 kcals/day or
physical activity must be increased by ~ 500 kcals/day

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iets that promise 10 to 15 pounds of weight loss per week do not efficiently attack fat stores

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-these types of diets reflect lean tissue and fluid (water) loss

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to lose one to two pounds of fat stores per week often requires limiting kcal intake

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-1200 kcal per day for women
-1500 kcal per day for men
-calorie allowance could be higher for very active individuals

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-at this time the low-fat

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high-fiber approaches have been the most successful

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monitoring total calorie intake

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-read labels to monitor calorie intake
-many foods are more energy-dense
-record food intake for 24 hours and calculate calorie intake
-consider eating healthy a lifestyle change, rather than a weight loss plan
-liquid calories do not stimulate satiety mechanisms to the same extent as solid food
-try to use beverages that have few or no calories (limit sugar-sweetened beverages)

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2005 Dietary Guidelines advice related to physical activity for adults

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-60 minutes of physical activity per day to maintain body weight and prevent weight gain
-60 to 90 minutes per day for maintaining weight loss

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pedometers

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monitor activity as steps
-recommended goal is 10,000 steps/day

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calorie counters (Bodybugg)

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track calorie expenditures
-calculate calories by measuring heart rate, sweat rate or heat loss and production

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Behavior Modifications for weight loss

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chain breaking, stimulus control, cognitive restructuring, contingency management, self-monitoring, relapse prevention

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chain breaking

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-separates behaviors that tend to occur together
-snacking on chips while watching television

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-stimulus control

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-altering the environment to minimize the stimuli for eating
-remove foods from sight; store foods in kitchen cabinets
-push tempting foods to the back of the refrigerator
-avoid the path by the vending machine
-shop from a list; avoid shopping when hungry
-provide a positive stimulus by keeping low-fat snacks available to satisfy hunger/appetite

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-cognitive restructuring

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-changes one’s frame of mind concerning eating
-substitute other pleasures for rewards
-after a hard day, avoid using alcohol or comfort foods as a quick relief for stress
-take a relaxing walk or have a conversation with a friend

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contingency management

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-form a plan of action to respond to situations where overeating is likely or physical activity is
hindered
-at parties or buffets try to set limits
-if raining, have other options for physical activity

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-self-monitoring

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-tracking foods eaten and conditions affecting eating
-helps people understand their eating habits
-record can encourage new habits that will counteract unwanted behaviors
-experts note that this is a key behavioral tool to use in a weight-loss program

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-relapse prevention

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-series of strategies used to help prevent and cope with weight control lapses
-recognize high risk situations and decide beforehand appropriate responses
-maintenance of weight loss is fostered by the “3 Ms”
-motivation, movement and monitoring

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Professional Help

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-primary care (family) physician
-assess overall health and appropriateness for weight loss
-registered dietitian
-help design a specific weight loss plan
-exercise physiologist
-provide advice concerning programs to increase physical activity

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Weight Loss Organizations

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-TOPS (Take Off Pounds Sensibly)
-Weight Watchers
-Jenny Craig and Physicians Weight Loss Center are less desirable due to expense (intense counseling
and mandatory diet foods/supplements)

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drug therapy alone has

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not been found to be successful

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three main classes of medications

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-amphetamine-like medications
-sibutramine (Meridia)
-orlistat (Xenical)

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-amphetamine-like medications

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-Fastin or Ionamin
-prolongs the action of epinephrine and norepinephrine in the brain
-contraindicated for pregnant/nursing women or individuals under the age of 18

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-sibutramine (Meridia)

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-approved by the FDA for weight loss
-reduces the reuptake of neurotransmitter and norepinephrine in the brain
-these neurotransmitters remain active in the brain for a longer time period
-prolong a sense of reduced hunger
-used with caution in individuals with hypertension and cardiovascular disease

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-orlistat (Xenical)

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-approved by the FDA for weight loss
-inhibits lipase enzyme activity in the small intestine
-reduces fat digestion and absorption
-increased fat in feces may lead to gas, bloating and an oily discharge
-reduced absorption of fat-soluble vitamins may require a supplement
-a low dose form of orlistat (AlliTM) is available over-the-counter without a prescription

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severe, morbid obesity

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(weighing at least 100 pounds over healthy body weight or twice one’s healthy
body weight; BMI > 40) requires professional treatment

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very-low-calorie diets (VLCD)

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-also known as protein-Sparing Modified Fast (PSMF)
-the main reasons for weight loss are minimal energy consumption and the absence of food
choices
-physical activity and resistance training can lead to a greater loss of adipose tissue
-about 3 to 4 pounds can be lost per week
-physician monitoring is crucial
-major health risks include heart problems and gallstones

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very-low-calorie diets (VLCD)

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Optifast program
-allows a person 400 to 800 kcals/day, often in liquid form
-120 to 480 kcals are carbohydrates
-280 to 400 kcals are high quality protein

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low carbohydrate intake often causes

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ketosis, which may decrease hunger

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bariatric surgery

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bariatrics focuses on the treatment of obesity

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two types of bariatric operations

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adjustable gastric banding (lap-band procedure)
gastroplasty (gastric bypass surgery)

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gastroplasty (gastric bypass surgery)

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-stomach stapling
-the most common and effective approach is the Roux-en-Y gastric bypass procedure
-reduces the capacity of the capacity and bypasses a short segment of the
upper small intestine
-overeating solid foods results in discomfort or vomiting
-promotes a more rapid satiety

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adjustable gastric banding (lap-band procedure)

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-the opening from the esophagus to the stomach is reduced by a hollow gastric band
-creates a small pouch and a narrow passage into the rest of the stomach
-this decreases the amount of food that can be eaten comfortably
-the band can be inflated/deflated via an access port just under the skin

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-bariatric surgery advantages

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-when enforced with food reduction, individuals can lose excess body weight
-can lead to dramatic health improvements
-reduced blood pressure
-elimination of type 2 diabetes

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-bariatric surgery disadvantages

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-cost; may not be covered by medical insurance
-follow-up surgery to correct stretched skin
-surgery promotes lifestyle changes which could require difficult behavior
adjustments
-diet and physical activity cannot reduce fat deposits in certain body locations
-suction lipectomy
-surgical removal of fat
-“problem” local fat deposits can be reduced in size
-risks include infections, lasting depressions of the skin and blood clots (can lead to
kidney failure or death)
-procedure’s expensive cost is an issue

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Underweight

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BMI less than 18.5

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Causes of underweight

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-eating disorders (anorexia nervosa)
-cancer
-infectious disease
-digestive tract disorders
-excessive physical activity
-genetics
-smoking

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Health Problems of underweight

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-loss of menstrual function
-low bone mass
-slow recovery from illness
-complications with pregnancy and surgery

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Interventions of underweight

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-medical intervention through a physician
-increase portion sizes
-in growing children, the high demand for calories to support physical activity and growth can
cause underweight
-gradually increase the consumption of calorie-dense foods (especially those high in vegetable fat)
-Italian cheeses, nuts and granola are good energy sources and are low in saturated fats
-dried fruits and bananas are good fruit sources
-fruit juices and smoothies are good energy sources (to replace diet soft drinks)
-regular meal and snack schedule can aid in weight gain and maintenance
-some may be too busy to eat
-reduce physical activity if excessively active

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How to Recognize an Unreliable Diet

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-promote quick weight loss
-initial weight loss results from the loss of water and lean muscle mass
-limit food selections and dictate specific rituals
-use testimonials from famous people and tie the diet to well-known locations
-cure-alls; claim to work for everyone
-often recommend expensive supplements
-no attempts are made to permanently change eating habits
-critical and skeptical of the scientific community
-claim that there is no need to exercise

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Types of Popular Diets

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-Low- or Restricted-Carbohydrate Approaches
-Carbohydrate-Focused Diets
-Low-Fat Approaches
-Novelty Diets
-Meal Replacements

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Quackery

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(people taking advantage of others) is Characteristic of Many Popular Diets

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Vitamins

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-essential organic substances needed in small amounts
-required for normal function, growth and maintenance of the body

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Characteristics of vitamins (1-4)

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1. Yield no energy (0 kcals/gram)
2. Some are fat-soluble (A, D, E and K)
3. Some are water-soluble (B and C)
4. Many function as coenzymes
-coenzymes help enzymes function properly
-B vitamins and vitamin K function as coenzymes

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Characteristics of vitamins (5-6)

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5. Vitamins are essential in human diets
-most cannot be synthesized in the human body
-exceptions
-vitamin A can be synthesized from certain plant pigments
-bacteria in the large intestine synthesize vitamin K and biotin
-vitamin D can be synthesized by the body if the skin is exposed to sunlight
-niacin can be synthesized from the amino acid tryptophan
6. Two criteria for vitamin classification
-the body is unable to synthesize enough of the compound to maintain health
-absence of the compound from the diet for a defined period produces deficiency
symptoms which (if caught in time) are quickly cured when the substance is resupplied

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Characteristics of vitamins (7-9)

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7. Vitamin deficiencies can lead to disease
8. A few vitamins have proved useful in treating several non-deficiency diseases (require the
administration of megadoses)
-megadoses of niacin may be utilized as a blood cholesterol-lowering reducing treatment
9. Both plant and animal foods supply vitamins in the human diet

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fat-soluble vitamins are

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not readily excreted from the body (except vitamin K)

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water-soluble vitamins are

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excreted rapidly by the kidneys
-vitamin B-6 and B-12 are exceptions and are stored more readily

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Fat-soluble vitamins (including vitamins A and D) that are not readily excreted may

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accumulate in the body and cause toxic effects
-vitamin A poses the greatest risk of toxicity

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-some vitamins (including vitamin E, niacin, vitamin B-6 and vitamin C)

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can produce toxic effects
if consumed in large quantities

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Fat-Soluble Vitamins

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A, D, E and K)
-absorbed with dietary fat
-stored mostly in the liver and fatty tissues

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-problems associated with the normal digestion and absorption of fat also interferes with

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the proper absorption of fat soluble vitamins
-diseases like cystic fibrosis in which fat absorption is hampered