Nutrition - Energy Balance

energy balance

the relationship between energy intake and energy expenditure

energy equilibrium

when cals consumed match the amount of energy used

positive energy balance

energy exceeds use and results in weight gain

negative energy balance

energy intake is less than use and results in weight loss

when is positive energy balance desired?

growth stages (pregnancy, infancy, childhood, adolescence)

Does aging cause weight gain?

No, excess food intake, limited physical activity, and slower metabolism does

when is negative energy balance desired?

In adults when body fat exceeds healthy levels (can impair growth in growth stages)

How is energy in food measured?

nutrient databases, bomb calorimeter, calclations

what does the body use energy for?

basal metabolism, physical activity, and digestion, absorption, and processing of ingested nutrients

thermogenisis

minor amount of energy used during fidgeting or shivering

basal metabolism

1. minimum amount of energy used when not eating and at rest

2. 60-70% of energy use

3. involves beating of heart, respiration of lungs, and other organ activity

(if a person is eating or not resting, resting metabolism is used)

. How is BMR expressed?

number of cals burned per unit of time (women .9 cal/kg per hour and men 1 cal/kg per hour)

What increases BMR?

Greater muscle mass, larger body surface, male gender, body temp, high secretions of thyroid hormones, nervous system activity, growth stages, caffeine and tobacco use, recent exercise

What decreases BMR?

low secretions of thyroid hormones, restricted calorie intake, less body surface and muscle mass, after age 30

How does physical activity increase BMR?

increases energy use above basal needs by 25-40%

Thermic effect of food (TEF)

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

2. 5-10% energy use

3. influenced by food composition and size (larger and protein rich foods use more energy)

Direct calorimetry

1. estimates energy use by measuring amount of heat produced by body (60% of energy leaves by heat)

2. measured by placing person in insulated chamber surrounded by water, change in temp

Indirect calorimetry

1. collects expired air

Estimated Energy Requirements

Calculation of energy needed based on weight, height, gender, age and physical activity level

Hunger

1. Physiological drive to find and eat food

2. controlled by internal mechanisms

Appetite

1. Psychological drive to eat

2. effected by external factors

Satiety

fulfilling hunger and appetite drives where we no longer have the drive to eat, controlled by hypothalamus

Hypothalamus role in eating

1. communicates with endocrine and nervous system

2. integrates internal clues of blood glucose levels, hormone secretions, and sympathetic nervous system

3. if they stimulate satiety center, we stop eating; stimulate feeding center, we eat more

Signals to eat include...

1. body starts to use energy from stores and causes feeling of satiety to diminish

2. endorphins and hormones stimulate appetite (cortisol and ghrelin)

What is recommended to include when measuring body composition:

1. total body fat

2. location of body fat

3. weight-related medical problems

Body Mass Index

1. weight for height standard

Underweight (BMI < 18.5)

Healthy Weight (BMI 18.5 to <25)

Overweight (BMI 25 to <30)

Obese (BMI >30)

(Not appropriate for everyone)

What are the desirable amounts of body fat?

Men 8-24%

Women 21-35% (need more fat for reproduction)

Underwater weighing

1. weight is measured under water and in air

2. formula for differences in densities of fat and lean tissue

3. accurate

Air displacement

The space a person takes up in a chamber is measured

Skinfold thickness

calipers used to measure fat layers under skin

bioelectrical impedance

painless low-energy electrical current sent through body, greater resistance, more adipose tissue

dual energy x ray absorptiometry (DEXA)

most accurate, whole body scan

android obesity

1. upper body obesity

2. related to heart disease, hypertension, and type 2 diabetes

3. seen in males, diets with high glycemic load, alcoholics, and smokers

gynoid obesity

1. lower body obesity

2. smaller abdomen and larger buttocks and thighs

3. seen in women

4. after menopause estrogen falls and women gain more abdominal fat

Set-Point Theory

genetically predetermined body weight or fat content that is closely regulated

What two things are involved in body weight and composition

nature and nurture

what is the treatment of overweight and obesity?

LONG TERM lifestyle changes

what do sound weigh loss programs include?

control of energy intake

regular physical activity

control of problem behavior

what is the only routinely successful way to treat obesity?

surgery

weight cycling

regaining weight after losing it

what do weight loss drugs do?

enhance norepinephrine and serotonin activity in brain

gastroplasty

reduces stomach capacity to 30 ml or bypasses a short segment of the small intestine

disordered eating

mild, short-term changes in eating patterns

eating disorder

1. more severe distortions of eating process that can become life threatening

2. obesity, anorexia, bulimia, binge-eating, EDNOS

what are disorders linked to?

1. being female

2. psychological reasons

anorexia nervosa

1. extreme weight loss, distorted body image, morbid fear of obesity

2. 1 in 200 adolescent females

3. most common in white females, competitive, family conflict

physical effects of anorexia

1. losing 15% of normal body weight

2. low body temp and metabolic rate

3. loss of hair, dry skin (lanugo)

4. slow heart rate and easily tired

5. loss of period bc not enough fat for estrogen

6. may not be able to have kids

treatment of anorexia

multidisciplinary teams (physicians, dietitians, psychologists, etc)

bulimia nervosa

binge eating followed by attempts to purge, 50% have depression

physical effects of bulimia

1. bad teeth

2. chipmunk look

3. stomach ulcers

4. constipation

treatment of bulimia

1. nutrition therapy (develop regular eating habits)

2. psychological therapy

binge eating disorder

1. eating large amounts of food, often overweight`

treatment of binge eating

1. nutrition therapy

2. psychological therapy

how to prevent eating disorders?

1.promote good self esteem

2. size acceptance