Energy Balance

By Jennifer Turley and Joan ThompsonBy Jennifer Turley and Joan Thompson

© 2013 Cengage© 2013 Cengage

Presentation Overview• Energy Balance Equations

• States of Energy Balance

• Energy Intake verses Expenditure

• Components of Energy Expenditure

Principles of Energy Balance• 1 pound fat = 3500 Calories stored. • To lose body fat, a Calorie deficit needs to

be created.• To gain body weight, a Calorie excess

needs to be created.

Body weight changes are based on the relationship of Caloric (Energy) intake & Energy Expenditure.

Energy Balance Equations• If Calories Consumed = Calories Expended

– Body weight is typically maintained. Energy balance occurs.

• If Calories Consumed > Calories Expended– Weight is typically gained . Positive energy balance occurs.

• If Calories Consumed < Calories Expended– Weight is typically lost. Negative energy balance occurs.

Energy Intake

• Consumption of Energy Producing Nutrients in Food and Beverages – Protein (4 Calories per gram)– Carbohydrate (4 Calories per gram)– Fat (9 Calories per gram)– Alcohol (7 Calories per gram)

• All of the Calories add up!

Energy Expenditure• Basal Metabolic Rate (BMR)

» An amount of energy needed to sustain life

• Voluntary muscle movement» Calories burned in physical activity (PA)

• The specific dynamic action (SDA) of food (also called the thermic effect of food)

» Energy required for food digestion & processing

Energy Expenditure

~60% BMR

Energy Expenditure

Basal Metabolic Rate (BMR):• The energy required by the body to minimally

function (heart to beat, lungs to breathe, …). • It is determined in a fasting state (12 hours)

and when the body is at complete rest. • Majority of expenditure in a sedentary person.

Energy Expenditure

Resting Energy Expenditure (REE):• Is similar to BMR.• It considers the amount of energy burned by

a person at rest. • REE can be measured in the lab or

estimated using the Mifflin Equations.

The Mifflin EquationsAre based on gender, height, weight, and age

REE Formula For WOMEN: • REE (Calories/day) = • (10 x W) + (6.25 x H) – (5 x A) - 161

REE Formula For MEN: • REE (Calories/day) = • (10 x W) + (6.25 x H) – (5 x A) + 5

W= Weight in Kg (pounds divided by 2.2)H = Height in centimeters (inches x 2.54)A= Age in years

Factors Affecting BMR/REE• Age: BMR is reduced with age.• Gender: More lean mass means a higher BMR

(gender differences). • Physiological State: Illness, pregnancy, lactation,

stress, metabolic diseases like hyperthyroidism can increase the BMR. Starvation or prolonged fasting decreases BMR up to 80% in women & 60% in men.

• Environmental Temperature: Hot or cold temperatures increase BMR.

Energy Expenditure

Physical Activity (PA): • The energy expended to perform

physical activity.• Voluntary muscle movement.• The total amount of energy

expended increases with body weight and the intensity of the exercise.

Physical Activity & Calorie Burn• The BMR or REE can be used to determine

energy spent or Calorie burn in PA.• Calories burned = Hours spent in activity x

REE x Activity Factor ÷ 24 hours/day. • Activity factors

• Sleeping/Reclining: Factor of 1• Very Light Activity: sitting or standing in a

small space: Factor of 1.5• Light Activity: moving without sweating:

Factor of 2.5• Moderate Activity: moving and sweating:

Factor of 5.0 • Strenuous Activity: all out efforts that cannot

be sustained for more than a few minutes without exhaustion: Factor of 7.0

Energy ExpenditureSpecific Dynamic Action (SDA): • The food processing charge. • Also called the thermic effect of food. • ~10% of the total number of Calories consumed

is required for the digestion, absorption & assimilation of nutrients into the body.

• Metabolism is increased when fed.

Summary• Energy balance is the state of energy intake

verse energy expenditure.• Intake occurs with food consumption.• Expenditure occurs by BMR, PA, & SDA.

Weight gain & body fat accumulation occurs with positive energy balance.Weight loss & fat mass reduction occurs with negative energy balance.

References for this presentation are the same as those for this topic found in module 4 of the textbook