Project 3: Personal Nutrition Assessment – Energy Needs and Anthropometry
A. Energy Needs Assessment
The factorial estimation methods of determining energy (TEE = 2,176 kcal/day) do provide similar estimates of energy expenditure indicated from the Diet Analysis Plus (2,149.5 kcal/day) from my activity records. The results from my three REE values, however, vary drastically, and the average between the three methods – 1,280 kcal/day – is significantly lower than the result from the Diet Analysis Plus program – 2,149.5 kcal/day. This leads me to believe that my high activity level, which allows me to have a higher PAL level, is a significant source of kcal/day when considering TEE. Additionally, the three methods for calculating REE were fairly similar (Figure 1), showing that my information was fairly consistent.
A major source of difference between the REE using factorial estimation methods and the Diet Analysis Plus program may be due to my strict exercise routine (this is not including PAL). When I look at my TEE and take into consideration the PAL, the amount of kcal/day accurately reflects my averages from the Diet Analysis Plus program. I enjoy going to the gym and try to exercise for about an hour 4-5 times per week, alternating between cardio and strength training each gym session. In the "easy to use" formula, only my weight and gender are taken into consideration, leaving plenty of room for error in total kcal/day. This is also true of the WHO equation, which uses standard numbers and weight in kilograms in order to calculate final kcal/day. These errors may stem from inaccuracy within the equation, since other factors, such as height, amount of exercise and bone structure are not taken into consideration. The Harris-Benedict equation includes height, weight and age, which provides a more accurate caloric equation, but also excludes exercise in the final kcal/day. Since all three equations are strictly based on anthropometric data – height and weight – there may be inaccurate totals for kcal/day when exercise is not considered. Then, adding the PAL level to the TEE creates a final total for the amount of kcal/day, but still excludes some of the factors I listed above.
One other factor to consider when looking at records from REE using factorial estimation methods and the activity records from Diet Analysis Plus is how much fat verses how much muscle I have. The REE and TEE equations only take into consideration my weight, not body structure. There are a few scenarios that I can think of that might allow different people to come up with the same average kcal/day, but have very different body compositions. The similarity of total kcal/day, but variation between people all lead to sources of error when considering the factorial methods of calculation TEE. For example, Person A could be very tall and thin, eat anything she wants without gaining weight and weighs an average of 120 lbs. Person B works out at the gym a lot, has a lot of muscle and very little fat, eats moderately and weighs 120 lbs. Person C is average height and has a slow metabolism, eats moderately to less than most people and weighs 120 lbs. Finally, Person D is extremely short, does not exercise but eats excessively and weighs 120 lbs. All four people weigh the same amount, but vary in muscle mass, percent body fat, the amount of food consumption and amount of time exercising. The inability to include these factors in the three TEE formulas could lead to inaccurate information for individuals, while displaying similar numbers for the general population.
There are also sources of error to consider when looking at the information from the Diet Analysis Plus Program. One factor is that all the activities I put into the computer have a set amount of calories burned. The program is not equipped to take individual variations into consideration. So, according to the program, everybody that sleeps for 450 minutes has a rate of 0.9 kCals/kg/hour and will burn 355 calories. And, everybody that showers and towel dries for 30 minutes has a rate of 4 kCals/kg/hour and will burn 105 calories. In this case, the computer cannot distinguish between somebody showering for 25 minutes and drying off for 5 minutes and somebody who showers for 15 minutes and takes their time to dry off for 15 minutes. These minor differences add up when taking into consideration a whole day's worth of exercise. Finally, "unaccounted" activities automatically input a rate of 1.1 kCals/kg/hour. My unaccounted time though, may be different from somebody else's and drastically different if my time is significantly less or more than another person.
Another problem with the Diet Analysis Plus program is that there are not enough exercises listed to include the actual activity. For example, I like to do the elliptical for 20 minutes at Rec Hall when I go to the gym. But, when I tried to put this information into the program, the elliptical was not listed as an exercise machine. The closest machine was a conditioning exercise, which is not the same and has a different rate of burning calories than the elliptical. Therefore, my information is incorrect for both days.
One final problem with the Diet Analysis Plus program is that my exercising information may be incorrect. What I mean by this is that I walked on the treadmill and I walked to and from classes, but I do not know the rate of how fast I walked and/or I did not walk at a steady pace. Therefore, I had to guess at my average walking rate, which may allow my total calories burned to be higher or lower than they actually are.
The methods of calculating energy expenditure are very similar to my caloric intake. My TEE is estimated at about 2,149.5 kcal/day, while my caloric intake from my one-day record was 2,110 kcal/day. According to this information, I am expending slightly more calories/day than I am taking in, but the difference is negligible. After looking at my REE, TEE and caloric intake, I would say that these equations are consistent, reliable and valid; leading me to believe that they are a fairly accurate depiction of how many calories I am consuming and burning each day.
Figure 1 – TEE using Factorial Estimation Methods
"Easy to Use" Formula / 1,171.2 kcal/dayHarris-Benedict Equation / 1,375 kcal/day
WHO Equation / 1,293 kcal/day
Average kcal/day / 1,280 kcal/day
B. Anthropometric Assessment
After obtaining anthropometric data, I can draw conclusions about my weight, body fat and lean body status. According to the 1983 metropolitan life tables and the frame size using elbow breadth, I have a small frame and have an average weight within the range of having a small frame. Additionally, I have a normal, healthy BMI classification and my waist circumference is below the cutoff for risk of disease. All these things lead me to believe that I have a healthy weight, and are average for my age and height.
I can also assess my body fat and lean body status. I calculated my body fat, taking into consideration my height and weight and determined that I have an estimated body fat of 14.4% (17.3 pounds of fat). I then calculated my percent body fat when taking into consideration my waist size and weight and have an estimated body fat of 12.8%, or 15.4 pounds of fat. Finally, I calculated my percent body fat after taking into consideration my age, weight, gender, the circumference of my calf, thigh, wrist and hips. After this more extensive test, I found out that I have about 18.6% body fat, which is broken down into 21.6 pounds of fat and 98.4 pounds of lean muscle, bone and body water components. All three of my calculations put me in the athletic classification for body fat percentage categories, leading me to believe that I have little excess fat and have built lean body tissue over time from my disciplined exercise regimen at the gym. One final look at my percentiles for MAC, TSF, AMA and calf circumference (all below average) reinforce that I am not overweight and do not have a lot of body fat, but have a lean body status.
I do agree with the numbers in the anthropometric data and the charts, although I think that there are sources of error with some assessments. For example, a body builder might be in the overweight category for BMI and desirable weight, when in fact he has little body fat but a lot of muscle. While I think that these classifications are not full proof, I do believe that I am average for my height and age, do not have a lot of body fat and am fairly lean from gym training and athletics.
After reviewing the anthropometric data, I can see a main source of error that may contribute to some of my final averages (although I still think they are fairly accurate). Our group did not have enough time to generate four different trials of information for elbow breadth, MAC, calf circumference or triceps skinfold. During the class period that we spent measuring our height, weight and other anthropometric data we had four people instead of three. This slowed us down in our measurements considerably. Also, after our group gathered information for elbow breadth, MAC, calf circumference and triceps skinfold, we realized that our calculations were done incorrectly. This put us back to square one and we did not have enough time to start over and get four trials in for four different people in four categories. Therefore, we only have one set of data for each of the four categories of elbow breadth, MAC, calf circumference and triceps skinfold. This means that I could not generate an average, but am strictly going off of one measurement for these categories.
Another possible source of error may be our measurement instruments. Although this source of error may lead to minor differences in measurement, each group’s instruments may all be slightly different, accounting for differences in data when taking into consideration that MAC and calf circumference is supposed to be read to the 0.1 cm and triceps skinfold to the ½ mm. One final source of error may be people in our nutrition class. Although everybody tries their best to eyeball each measurement, not every person reads the instruments the same. Also, we may be placing the instruments slightly higher or lower than they should be on the calf or arm, creating consistency among individuals, but subtle differences among classmates.