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ENERGY IN VERSUS ENERGY OUT

ESTIMATING ENERGY REQIREMENTS

BODY WEIGHT, BODY COMPOSITION, AND

HEALTH

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Nutrient Density

A measure of the nutrients a food provides relative to the energy it provides.

The more nutrients and fewer the kcalories, the higher the nutrient density.

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Calories and KcaloriesA calorie is a unit by which energy is measured.

Food energy is measured in kilocalories.

1000 calories equal 1 kilocalorie, abbreviated kcal.

One kcal is the amount of heat necessary to raise the temperature of one kilogram of water 1° C.

Empty Calorie-food that contributes energy, but lack protein, vitamins and minerals

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Energy

The capacity to do work

The energy in food is chemical energy.

The body converts this chemical energy to mechanical, electrical, or heat energy.

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Energy From Food

The amount of energy a food provides depends on the amount of carbohydrate, protein, and fat it contains.

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Energy From Food {continued}

1 gram of carbohydrate yields 4 kcals of energy.

1 gram of protein yields 4 kcals of energy.

1 gram of fat yields 9 kcals of energy.

Alcohol is not a nutrient because it interferes with growth, maintenance, and repair of the body, but it does yield energy when metabolized in the body. 1 gram of alcohol yields 7 kcals of energy.

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Energy Balance is Best

• Want energy balance

• For each 3500 kcals consumed and not burn = 1 pound

• Amount of energy in should = energy out– If not either gain wt or lose wt

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Food CompositionBomb calorimeter- an instrument that measures

the heat energy released when foods are burned. This is a measure of direct calorimetry.

Direct calorimetry measures the amount of heat released.

Indirect calorimetry measures the amount of oxygen consumed.

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Food Intake

Hunger- the physiological drive for food that initiates food-seeking behavior.

Satiation- the feeling of satisfaction that occurs during a meal and halts eating. This determines how much food is consumed during a meal.

Satiety- the feeling of satisfaction that occurs after a meal and inhibits eating until the next meal. This determines how much time passes in between meals.

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Physiological Influences•Empty stomach•Gastric contractions•Absence of nutrients in small intestines•GI hormones•Brain peptides

Sensory Influences•Thought, smell, sight, taste of food

Cognitive Influences•Presence of others, special occasions•Perception of hunger•Favorite, ethnic, or religious foods•Time of day•Abundance of food

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Post-ingestive Influences•Food in stomach triggers stretch receptors•Nutrients in small intestines elicit hormones

Post absorptive Influences•Nutrients in the blood signal the brain about their availability, use, and storage.•As nutrients dwindle, satiety diminishes.•As satiety diminishes, hunger develops and the cycle begins again.

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Energy ExpenditureBasal metabolism- energy needed to maintain

life when a body is at complete rest after a 12 hour fast.

Physical activity- voluntary movement of skeletal muscles and support systems. This is the most variable component of energy expenditure.

Thermic effect of food- estimation of the energy required to process food (digest, absorb, transport, metabolize, and store nutrients).

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Basal Metabolism~ 2/3 of energy the average person spends in a

day supports the body’s metabolic activities.

Basal metabolic rate (BMR)- the rate of energy use for metabolism under basal conditions, usually expressed as kcal per kg body weight per hour.

Resting energy expenditure (REE)- similar measure of energy output, usually less precise than BMR due to less strict criteria regarding rest and fasting.

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Factors Affecting the BMR

Factor Age

Height

Growth

Body composition

Fasting Smoking

Effect on BMR BMR decreases with

increasing age In tall, thin people, BMR is

higher In children and pregnant

women BMR is higher The more lean mass, the

higher the BMR, the more fat, the lower the BMR

Fasting/starvation lowers BMR Nicotine increases BMR

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Harrison-Benedict Equation For Estimating BMR

Men: 66 + (13.7 x wt in kg) + (5 x ht in cm) – (6.8 x age in years).

Women: 655 + (9.6 x wt in kg) + (1.8 x ht in cm) – (4.7 x age in years).

*Weight in pounds divided by 2.2 equals kilograms.

*Height in inches times 2.54 equals centimeters.

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Activity Factors

1.3 ------------------------------------------------>2.4

Sedentary Professional Athlete

Type of Activity Activity Factor

Walking (2.5-3mph) 1.5

Cycling, tennis, walking (3.5-4mph) 1.6

Basketball, football, soccer 1.9

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Quick Method for Estimating Energy Needs

25-35 kcals per kilogram.

Depends on % ideal body weight (IBW).

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Body Weight and Its Standards

Body Mass Index (BMI)

An index of a person’s weight in relation to height, determined by dividing the weight (kg) by the square of the height (m) (or wt lb divided by ht in squared x 703)

<18.5 = underweight 18.5-24.9 = normal 25-29.9 = overweight > 30 = obese

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Body Weight and Its Standards {continued}

Hamwii Rule of Thumb.

Men- 106 # for the first 5 feet and 6 pounds for every inch thereafter.

Women- 100# for the first 5 feet and 5 pounds for every inch thereafter.

* +/- 10% for small or large frames.

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Body Weight and Its Standards

{continued}

Various tables and charts are also available listing standards of body weight

Dietary Guidelines for Americans

Standards for Older Americans

Met Life Standards

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Body Fat Distribution

Intra-abdominal fat- fat stored within the abdominal cavity in association with internal abdominal organs. This type of distribution represents a greater health risk.

Central obesity- excess fat around the

trunk. Common in post-menopausal women

and associated with an increased risk for cardiovascular disease. This type of fat is referred to as “apple” shaped.

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Body Fat Distribution{continued}

Lower body fat- fat centered around the hips and thighs. This has proved to be relatively harmless and is referred to as “pear” shaped.

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Methods Of Measuring Body Fat

Fatfold Measure- a clinical estimate of total body fat in which the thickness of a fold of skin in various places of the body is measured with calipers.

Waist to hip ratio- taking the measurement of the waist divided by the measurement of the hips in inches. A ratio > than 0.80 in women or 0.90 in men may indicate a high risk for health problems.

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Methods Of Measuring Body Fat {continued}

Hydrodensitometry- a method of measuring body density in which the person is weighed and then weighed again while submerged in water.

Dual energy X-ray absorptiometry- low dose x-rays that differentiate among fat free tissue (LBM) fat tissue and bone, providing a measurement of total fat and distribution

Bioelectrical Impedance- a method for estimating body fat using low intensity electrical current.

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Health Risks Associated With Excess Body Weight

and Body FatDiabetesHypertensionCardiovascular DiseaseSleep ApneaOsteoarthritisAbdominal HerniasCertain forms of CancerRespiratory Problems

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Health Risks Associated With Low Body Weight and

Body Fat

The main risk associated with being underweight is the body’s difficulty battling medical stresses if need be.

Underweight may cause infertility.