Energy Balance and Weight Control

Energy balance

the relationship between energy intake and energy expenditure

Energy equilibrium

when calories consumed matches the amount of energy expended

calories in = calories out

Energy balance

the relationship between energy intake and energy expenditure

Energy equilibrium

when calories consumed matches the amount of energy expended

calories in = calories out

Positive energy balance

energy intake exceeds energy expenditure and results in weight gain

calories in > calories out

Negative energy balance

energy intake is less than energy expenditure and weight loss occurs

calories in < calories out

Positive energy balance is desired during

growth stages

Ex: pregnancy, infancy, childhood, adolescence, and periods of recovery from illness.

Aging does not cause

weight gain

Negative energy balance is desired in adults

when body fatness exceeds healthy levels

not during growth stages (impairs normal growth pattern)

Calorie values are derived directly by

using a bomb calorimeter

(or determining the grams of the energy-providing macronutrients and alcohol)

3 main purposes of energy

basal metabolism

physical activity

digestion, absorption, and processing of ingested nutrients

Minor form of energy output is

thermogenesis: energy expended during fidgeting or shivering

Basal Metabolism (BMR)

minimum amount of energy expended in fasting to keep a resting, awake body alive in a warm, quiet environment

Accounts for about 60-70% of total expenditure

Processes involved include beating of heart, respiration of lungs, and activity of other organs

Factors that increase basal metabolism

Greater muscle mass

Larger body surface (height)

Being male

Increase body temperature

Higher than normal secretions of thyroid hormones

Nervous system activity

Growth stages

Caffeine and tobacco use

Recent exercise

Factors that decrease basal metabolism

Lower than normal secretions of thyroid hormones

Restricted calorie intake

Less body surface area and muscle mass

Aging after age 30 years

Physical activity increases

energy expenditure

Small lifestyle changes that influence more energy expenditure

going up the stairs

walk rather than drive

stand in the bus rather than sit

Thermic effect of food (TEF)

energy used to digest, absorb, transport, store, and metabolize

accounts for about 10% of energy consumedfood; it varies with the composition of the meal.

Thermogenesis

process of heat production

small contribution to total energy expenditure

produced when body expends energy for non-voluntary physical activity (triggered by extreme cold, overfeeding, trauma, starvation)

(fidgeting, shivering, maintaining muscle tone, holding body upright)

Total energy expenditure (TEE)

basal metabolism, thermic effect of food (TEF), activity energy expenditure (AEE)

Energy used by the body can be measured by

direct calorimetry and indirect calorimetry

Energy used can be estimated based on

height, weight, physical activity, age

Direct calorimetry

Estimates energy expenditure by measuring the amount of heat released by the body

About 60% of the energy the body uses leaves as heat

Heat release is measured by placing a person in an insulated chamber surrounded by a layer of water.

Change in temperature determines the amount of energy a person expends

Indirect calorimetry

Involves collecting expired air

Data tables can show the energy costs of different exercises

Estimated Energy Requirements (EERs)

Estimate energy needs based on weight, height, gender, age, and physical activity level

Energy expenditure peaks in which age group

19-30 years of age

Energy expenditure is lowest in which age groups

children and elderly

Hunger

physiological drive to find and eat food. controlled by internal mechanisms such as organs, hormones, hormonelike factors, nervous system

Appetite

psychological drive to eat. affected by external factors such as social custom, time of day, mood, memories, sight

Factors that impact hunger

Peripheral body systems, central nervous system, metabolic influences, disease states

Factors that impact appetite

disease influences, learned preferences and aversions, social influences, specific appetites, emotional influences, environmental factors, medication influences

The internal and external signals operating simultaneously to lead us to decide wheter to reject or eat food can be

overridden

Ex: eating dessert on a full stomach, ignoring hunger because we have no appetite for food being served

Satiety

the feeling of fullness and satisfaction that signals the end of eating.

Hypothalamus is the site of regulation for this

Hypothalamus

communicates with endocrine and nervous system

integrates internal cues of blood glucose levels, hormone secretions, and sympathetic nervous system

if internal signals stimulate the satiety center

we stop eating

if the internal signals stimulate feeding centers

we eat more

Satiety is elicited by

sensory aspects of food, knowledge that food has been eaten, chewing, expansion of stomach and intestines, effects of digestion, absorption, and metabolism

Low-energy dense foods

promote satiety

Hormone during digestion that shuts off hunger

cholecystokinin

Decrease of hormone ghrelin promotes

short-term satiety

Long-term satiety is promoted by

body composition and the amount of body fat

Adipose tissue secretes

leptin

Leptin function

reduces food intake, which decreases body fat

Process of satiety

1. flavor of food

2. knowing a meal was just eaten

3. Influence of stomach and intestinal expansion and activity

4. Influence of nutrient use in the liver and related communication with the hypothalamus and other regions of the brain

5. Conscious thinking takes place in the brain’s cortex and can overcome hunger or satiety signals

when concentrations of macronutrients fall in the body and the body uses energy from stores…

causes feelings of satiety to diminish

Endorphins and hormones that stimulate appetite and increase food intake

cortisol and ghrelin

Ghrelin

produced in the stomach

stimulates hunger

Leptin

produced by adipose tissue

suppresses hunger

(Eat less, increase energy expenditure)

Old ways of measuring body composition

weight-for-height tables

Modern ways of measuring body composition

total body fat

location of body fat

weight-related medical problems

BMI (weight-for-height) standard

applies to both men and women

measure of weight for height to estimate body fat

body weight (kg)/height² (meters)

body weight *703 (in lb)/height² (in inches)

BMI underweight

<18.5 kg/m²

BMI normal weight

18.5-24.9 kg/m²

BMI overweight

25-29.9 kg/m²

BMI obese

>30 kg/m²

BMI limitations

cannot distinguish between excess fat and muscle and bone mass

BMI does not account for

differences in body compositions. in very muscular athletes, it will overestimate boy fat content because muscle mass contributes an unusually high percent to total body mass

BMI may underestimate

body fat content in the elderly, many of whom have lost considerable amounts of muscle. body fat will constitute a higher percent of their total body mass than would be predicted by BMI

Desirable amounts of body fat in men

8% - 24%

over 24% is obese

Desirable amounts of body fat in women

21% - 35%

over 35% is obese (need more because of reproduction)

To measure body fat content

body weight and body volume must be measured

methods to measure body volume

underwater weighing

air displacement

Skinfold thickness

Bioelectrical impedance

Dual energy x-ray absorptiometry (DXA)

Underwater weighing

body weight is measured under water and in air

Air displacement

bodpod

the space a person takes up in a chamber is measured

Skinfold thickness

calipers used to measure fat layer under skin

Bioelectrical impedence

painless, low-energy electrical current sent through body

based on principle that body fat resists the flow of electricity because it is low in water and electrolytes

Dual energy X-ray absorptiometry (DXA)

The most accurate method

Measures body fat by releasing small doses of radiation through the body to assess body fat and bone density

whole body scan

Whole body scan estimates

body fat

fat free soft tissue

bone minerals

Apple shape

most common obesity shape in men and have a higher risk of chronic disease

Pear-shaped body

most common obesity shape in women and has a lower chronic disease risk than the apple shape

waist size greater than 35 inches for women

increased risk of obesity-related diseases in women.

waist size greater than 40 inches for men

increased risk of obesity-related diseases in men.

Visceral fat is

an independent health risk

cardiovascular disease, type 2 diabetes, insulin resistance, premature all-cause mortality

Factors that play a role in development of obesity

food environment, portions, more meals away from home, screen time, sleep deprivation, boredom and stress, stopping smoking, genetics

Children with no obese parents have

10% chance of becoming obese

Children with 1 obese parent

have a 40% chance of becoming obese

if both parents are obese, the child

has an 80% chance of becoming obese.

Identical twins raised apart show similar

weight gain patterns

Genes account for

40-70% of weight differences

body type, metabolic rate, factors that affect hunger and satiety

Set point theory

genetically predetermined body weight or fat content that is closely regulated

When energy intake is reduced, thyroid hormone secretions fall, slowing metabolism

When weight is lost, the body becomes more efficient at storing fat

It may also help prevent weight gain

Environment role on obesity

body weight similarities among family members may be more from learned behaviors

(couples and friends may behave similarly toward food)

when eating is appropriate

what is preferable to eat

how much is eaten

Nature and nurture are involved in

body weight and composition

Even with the genetic predisposition for leanness

it is possible to gain excess fat

even with genetic predisposition to obesity

it can be avoided with a healthy diet and regular physical activity

Treatment of overweight and obesity

long-term lifestyle changes. healthy, active lifestyles with lifelong dietary modifications should be emphasized

Sound weight-loss programs should include

control of energy intake, regular physical activity, control of problem behaviors

Weight loss program is considered successful when

those involved remain at or close to lower weights

Only __ of people following commercial diet programs succeed

5%

1/3 of weight lost is regained within

3 to 5 years

Currently, the only obesity treatment that shows success is

the surgical approach

Negative consequences of weight cycling

increased upper body fat

diminished self-esteem

decline in HDL cholesterol

Decline in immune system function

Adipose tissue contains

3500 kcal/lb

To lose 1 pound per week, energy intake must decreased by

500 kcal/day of physical activity increased by 500 kcal/day (or a combo!)

Women may need to limit kcal intake to

1200 kcal/day

Men may limit kcal intake to

1500 kcal/day

Expending 100 to 300 extra kcal/day above normal activity can lead to

a steady weight loss

NEAT

non-exercise activity thermogenesis

Chain breaking

separating behaviors that occur together

Stimulus control

alter the environment to minimize stimuli for eating

Cognitive restructuring

change frame of mind regarding eating

Contingency management

prepare for situations that may trigger overeating

Self-monitoring

track food eaten, when, why, how you feel, physical activities, body weight