By Jennifer Turley and Joan Thompson Energy Balance By Jennifer Turley and Joan Thompson © 2013 Cengage

Presentation Overview Energy Balance Equations States of Energy Balance Energy Intake verses Expenditure Components of Energy Expenditure BMR PA SDA

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 Equations Are 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: (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 Expenditure Specific 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