Unit 8 Calories and Energy 1

Energy

Energy

= kilocalories

= kcal

= Calories

Unit of measure used to

express the amount of

energy produced by foods

in the form of heat

Carbohydrates – 4 kcal/g

Protein – 4 kcal/g

Alcohol - 7 kcal/g

Fat – 9 kcal/g

2

Energy Metabolism 3

What do we need energy for?

Energy in food fuels body processes

- Muscular activity

- Growth

- Tissue repair and

maintenance

- Chemical processes

- Body temperature

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Total Energy Needs 5

Thermic Effect of

Food

Physical Activity

Basal Metabolism 60-75%

Approx. 30%

Approx. 10%

Basal Metabolism

Basal Metabolic Rate (BMR)

- the minimum Caloric requirement to sustain life in a

resting individual

- Breathing

- Heartbeat

- Body Temperature

- Growth

- Organ Functions

6

Estimate Energy Used for Basal

Metabolism

Men:

- BMR Calories = body weight (lbs) x 11

Women:

- BMR Calories = body weight (lbs) x 10

Varies ± 20%

- Depending on physical activity, muscle mass,

height, health status, genetic traits

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Factors that Effect BMR

Body composition - lean vs. fat tissue

Growth

Hormones

Fever

Height

Environmental temperature

Starvation, fasting, and malnutrition

Weight loss from dieting

Stress

Certain drugs

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Thermic Effect of Food

(Dietary Thermogenesis)

Amount of energy required to

digest, absorb, and metabolize

food

Resting Energy Expenditure

(REE)

= BMR + Thermic Effect of

Food

9

Physical Activity – Voluntary

Muscle Movements

Inactive

- sitting most of the day

- less than 2 hours of moving about slowly or

standing

Average

- sitting most of the day

- walking or standing 2-4 hours, no strenuous activity

Active

- physically active 4 or more hours each day

- little standing, some strenuous activities

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Measuring Caloric Need

Indirect Calorimetry

indirect estimate of resting energy

expenditure that measures the

ratio of CO2 expired to the

amount of O2 inspired

gold standard

rarely used in clinical settings due

to time and cost

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Estimating Total Caloric Need

Harris-Benedict Equation

Mifflin-St. Jeor Equation

Ireton-Jones Equation

Schofield Equations

Toronto Equation

“Rule of Thumb” = 30 kcal/ kg body weight

12

MyPyramid Caloric Estimates 13

Energy in Food

Carbohydrates – 4 kcal/g

Protein – 4 kcal/g

Alcohol - 7 kcal/g

Fat – 9 kcal/g

14

Energy in Food

Energy-dense foods

- provide relatively high levels of Calories

Energy-dense foods tend to be nutrient-poor

Nutrient-rich foods tend to be low in energy

US Diet tends to be high in energy-dense foods

15

Energy Metabolism 16

Estimate Calories by Food Groups

Food Group Ave. Calories / serving

Starch/grains 80

Fruits 60

Milk

skim or 1%

2%

whole

100

120

160

Nonstarchy Veggies 25

Meat and beans

Plant-based protein

Lean

Medium fat

High fat

varies

45

75

100

Fat/oils 45

Based on American Diabetes Association Exchange lists

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Calculating Calories in Food

Nutrient grams x calories/gram = calories

Example:

15 g carbohydrate x 4 kcal/g = 60 Calories

10 g protein x 4 kcal/g = 40 Calories

5 g fat x 9 kcal/g = 45 Calories

Total = 145 Calories

Most foods are a mixture

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Estimating Calories in a Recipe

Example: Ricotta Cheese Cookies

- 2 C sugar 774 x 2 = 1548

- 1 C butter 1628

- 15 oz. Ricotta cheese 560

- 2 tsp. vanilla extract 31 x 2 = 62

- 2 large eggs 72 x 2 = 144

- 3 ½ C flour 3.5 x 455 = 1593

- 2 tbsp. baking powder 0

- 1 tsp. salt 0

5535 / 36 =

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154 Calories per Cookie

How Is Caloric Intake Regulated?

Hunger

- Physical and psychological sensations

that lead people to acquire and eat food

- Causes weakness, stomach pains,

irritability

Satiety

- Feeling of fullness or of having eaten

enough

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How Is Caloric Intake Regulated?

Appetite

- The desire to eat

- A pleasant sensation aroused by

thoughts of taste and enjoyment of food

- Can override hunger and satiety mechanisms

Appetite may or may not relate to hunger

21

In vs. Out

Intake < TEE Intake = TEE Intake > TEE

22

OUT

Weight Change 23

vs. CALORIE INTAKE

(WHAT YOU EAT)

TOTAL ENERGY

EXPENDITURE

IN

CARBS

FAT

PROTEIN

BMR

Dietary

Thermogenesis

Physical Activity

WEIGHT GAIN WEIGHT LOSS

WEIGHT MAINTENANCE

Tips for increasing activity

Find something you enjoy

Use the buddy system

Spread activity over the

entire day if desired

Start slowly and gradually

increase activity

Keep moving / move more

Keep an activity log

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Calorie Requirements Homework

Go to http://www.bmrcalculator.org/

Do not get tempted by the pretty flashing

advertisements.

Input your information for age, gender, weight, and

height.

Discover your Calorie requirements based off of 2

estimating equations

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