ESTIMATING KCAL NEEDS:The best ―gold standard‖ estimating calorie needs of an individual is by indirect calorimetry. This special equipment measures the gas exchange in an individual and then provides the Resting Metabolic Rate (RMR).Advances in technology have made this more available however testing requires a person to breathe in an IC apparatus for several minutes.*Gaston College has the ReeVue Metabolic Equipment. See the video on course links!
KCALS:If IC equipment is not available, we have to use what is called ―predictive equations‖. These formulas are not perfect and may overestimate/underestimate actual kcal needs1. Harris Benedict • This measures expenditure of kcal at complete rest--- think of it as the amount of kcal to keep your body alive. This is called REE (resting energy expenditure) • After you calculate the REE you must multiply this number times an activity factor. This now gives you TEE or the total energy expenditure that a person ―burns‖ in kcals per day.
KCAL NEEDS:2. Mifflin St Jeor: This also measures REE but this formula is for obese individuals only! Once you calculate using the formula, this number would also be multiplied times an activity factor and stress/injury factor.3. Other formulas include Ireton Jones and Owen but we will not be reviewing these in DET 120. These are typically used in critical care by RDs.
SO…LET’S PRACTICE REE x AF (activity factor) = a person’s daily kcal needs or TEE Example: 40 year old female who is 5’4‖, 125 lbs, and has normal activities of daily living (ADLs) 64‖ = 162.6 cm 125 lbs = 56.8 kg REE (using Harris Benedict) = 655 + (9.6 x 56.8kg) + (1.7 x 162.6cm) – (4.7 x 40) REE = 655 + 545.3 + 276.4 – 188 REE = 1289 (yes you can round kcals!) Now---Multiply REE x activity or stress factor to figure out her total energy requirements (TEE). In this case I have selected 1.5 for an activity factor. 1289 x 1.5 = 1933 total kcals needed per day to support her body’s energy needs! Practice!
OTHER METHODS OF ESTIMATING KCALNEEDS Many RDs use a more simple method of estimating kcal needs (kcal/kg), but it requires more clinical judgment. You have a handout on this. Please work with your precepting RD to review use of shortcut method formulas.
EXAMPLESHealthy male is 165 lbs and exercisesmoderately. He has a normal weight for hisheight. How many kcals would he consume perday?165 divided by 2.2 = 75 kg (weight in kg)75 kg x 35 kcals/kg = 2625 kcals(I selected 35 kcals/kg because he has anormal weight and exercises moderately)
ESTIMATING THE BODY’SDAILY PROTEIN NEEDS: The RDA for protein is .8 g/kg/day. Many RDs simply round up to 1.0 g/kg/day as a practical measure. Remember: the RDA is for HEALTHY individuals only!
ESTIMATING THE BODY’S DAILY PROTEINNEEDS: When patients are stressed protein needs are higher. Stress may be caused by fever, infection, wound healing, surgery, burns, cancer, etc. We use a higher factor based on the patient’s level of physical stress. Refer to your handout to see reference ranges. RDs will often look at the patient’s albumin level (most commonly used) to determine how much physical stress they are under. If albumin is very low, protein needs are estimated higher per kg.
EXAMPLE1. Healthy individual is 60 kg (and we determined that the weight is normal for height). What are her protein needs? 60 kg x .8 g/kg/day (or round up to 1.0 g/kg/day) = 48-60 grams of protein per day2. A patient is experiencing infection and her albumin level is 2.2. She weighs 60 kg. What are her protein needs? Look at your handout for the reference range 60 kg x 1.2-1.5 g/kg/day (it increased!) = 72-90 g/kg/dayOur nutrition care plan would include ways to increase herprotein intake if she was not eating adequately. This is toinsure she receives the extra protein for healing!
BRAIN TEASER:If you have estimated that a person needs 60 grams of protein per day, how many oz of meat or cheese would this be?Check your exchange list. One exchange ofmeat/cheese/egg/peanut butter has 7 GRAMS ofprotein per serving! 60 grams needed per day divided by 7 grams/oz (1 protein exchange) = approx 8 oz per day!Recognize of course that a varied diet with grains,vegetables, and cow’s milk or soy milk would provide asignificant contribution to daily protein needs. Thinkof vegetarians—is it possible for them to easily meettheir protein needs?
ESTIMATING FLUID NEEDS Fluid needs are based on weight, age, exercise,and the normal losses that occur as a result ofsweat & cooling, and fever. Similar to protein, thecalculation is based on the number of kg of weight– see your fluid needs handout and practice!These figures are based on estimation of NORMALneeds. Fluid needs may be higher (fever) or lower(renal disease) depending on the patient’scondition. Keep in mind that fluids can be suppliedby our foods as well. Think of watery fruits andvegetables! It is not limited to just water---otherfluids can meet our daily fluid needs.