Energy Balance Module 4.2

Energy Balance Energy balance occurs when energy consumed equals energy expenditure. Energy is measured in kilocalories (kcal, kcalories) A kilocalorie is a measure of the amount of energy that is supplied to or expended by the body. https://www.gymjunkies.com/wp-content/uploads/2014/12/negative_energy_balance.jpg 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. 2

Energy Intake and Expenditure Protein (4 Calories per gram) CHO 4 kcal/g Fat 9 kcal/g gram Alcohol 7 kcal/g All of the Calories add up! Energy Expenditure Resting Energy Expenditure (REE): similar to BMR. Considers amount of energy burned at rest. REE can be measured in the lab or estimated using the Mifflin Equations.

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 Balance Metabolic rate represents the number of calories needed to fuel ventilation, blood circulation and temperature regulation. Calories are also required to digest and absorb consumed food and fuel the activities of daily life. Therefore, metabolic rate is an estimate of how many calories you would burn if you were to do nothing but rest for 24 hours. Metabolic rate epresents the minimum amount of energy required to keep your body functioning. Intake - hunger, appetite, portion vs serving size Expenditure Basal metabolism (breathing; heartbeat) sum of all chemical activities Physical (voluntary muscles movements) Lean Body Mass Thermic effect of food (digestion) specific dynamic action (SDA)

Energy Expenditure ~60% BMR

1. BMR (REE) Energy Expenditure Basal Metabolic Rate (BMR): (60-65%) The energy required by the body to minimally function (heart to beat, lungs to breathe, …). BMR measurements are typically taken in a darkened room upon waking after 8 hours of sleep and 12 hours of fasting to ensure digestive system is inactive, and with the subject resting in a reclined position. Majority of expenditure in a sedentary person. Resting Energy Expenditure (REE): Similar to BMR. Determines the number of calories you burn in a 24 hour period maintaining basic bodily functions, but also includes the number of calories burned eating and conducting small amounts of activity RMR measurements are typically taken under less restricted conditions than BMR REE can be measured in the lab or estimated using the Mifflin Equations.

The Mifflin Equations Are based on gender, height, weight, and age Resting Metabolic Rate (Calories/day) = REE Formula For MEN: 10 x weight (kg) + 6.25 x height (cm) - 5 x age (y) + 5 REE Formula For WOMEN: 10 x weight (kg) + 6.25 x height (cm) - 5 x age (y) - 161. 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.

2. Physical Energy Expenditure Physical Activity (PA) (25-35%): 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 An Activity Factor ÷ 24 hrs/d Activity Factors Sleeping/reclining 1 Very Light activity: sitting, standing 1.5 Light Activity- moving without sweating 2.5 Moderate activity – moving and sweating 5 Strenuous- if extended leads to exhaustion 7 https://stayhealthystayfitwebmag.files.wordpress.com/2014/05/favourite-physical-activity.gif

3. Digestion Energy Expenditure Thermic effect of food / Specific Dynamic Action (SDA): The food processing charge. ~10% of the total number of calories consumed is required for the digestion, absorption & assimilation of nutrients into the body. Metabolic processes increase when eating (chewing, swallowing); digesting (breaking food substances into smaller units); absorbing (moving digested units of food throughout the body). http://cdn.running.competitor.com/files/2012/05/3.jpg