MedGem Indirect Calorimeter Compared With Prediction Equations Such As Harris-Benedict

The American Dietetic Association determined that the MedGem hand-held indirect calorimeter offers advantages compared with prediction equations, in a group of overweight women, to determine Resting Energy expenditures and estimated Total Energy Expenditures during research screening.

Objective

To compare standardized prediction equations to a MedGem hand-held indirect calorimeter in estimating resting energy and total energy requirements in overweight women.

Design

Resting energy expenditure (REE) was measured by hand-held indirect calorimeter and calculated by prediction equations Harris-Benedict, Mifflin-St Jeor, World Health Organization/Food and Agriculture Organization/ United Nations University (WHO), and Dietary Reference Intakes (DRI). Physical activity level, assessed by questionnaire, was used to estimate total energy expenditure (TEE).

Subjects

Subjects (n39) were female nonsmokers older than 25 years of age with body mass index more than 25.

Statistical analyses Repeated measures analysis of variance, Bland-Altman plot, and fitted regression line of difference.

A difference within 10% of two methods indicated agreement.

Results

Significant proportional bias was present between hand-held indirect calorimeter and prediction equations for REE and TEE (P 0.01); prediction equations overestimated at lower values and underestimated at higher values.

Mean differences (+/- standard error) for REE and TEE between hand-held indirect calorimeter and Harris-Benedict were 5.98 46.7 kcal/day (P 0.90) and 21.40 +/- 75.7 kcal/day (P 0.78);

between MedGem hand-held indirect calorimeter and Mifflin-St Jeor were 69.93 +/- 46.7 kcal/day (P 0.14) and 116.44 +/- 75.9 kcal/day (P 0.13);

between MedGem hand-held indirect calorimeter and WHO were 22.03 +/- 48.4 kcal/day (P 0.65) and 15.8 +/- 77.9 kcal/day (P 0.84);

and between MedGem hand-held indirect calorimeter and DRI were 39.65 +/- 47.4 kcal/day (P 0.41) and 56.36 +/- 85.5 kcal/day (P 0.51).

Conclusions

A significant discrepancy between predicted and measured energy expenditure was observed.

Less than 50% of predictive equation values were within 10% of hand-held indirect calorimeter values, indicating poor agreement.

For more information on how you can measure RMR with a hand-held device, click on MedGem indirect calorimeter.

Source: J Am Diet Assoc. 2009;109:836-845