Patients with a long chain fatty acid oxidation disorder (LCFAOD) may have a reduced resting energy expenditure (REE) and total energy expenditure (TEE) compared to healthy controls, according to a study published in Molecular Genetics and Metabolism.

The study found that patients with LCFAOD had lower measured REE values than those estimated using published prediction equations for basal metabolic rate (BMR). The patients’ TEE values were also lower than the estimated values. 

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The REE and TEE values were also significantly lower than energy expenditure data for the general population published in Dietary Reference Intakes (DRI). The daily REE for the patients with LCFAOD was found to be 61 kcal lower than the control group which could lead to close to 500 kcal less energy expenditure per week. The TEE values were reduced by 101 kcal/day (P <.0015) for the patients with LCFAOD compared to the control data published in the DRI.

“Our results suggest patients with a LCFAOD exhibit a lower REE and therefore actually have a slightly lower TEE than estimated. Current prediction equations may overestimate energy expenditure of patients with a LCFAOD,” the study’s authors said.

Fat-free mass can affect REE values, but the FFM and fat mass of the patient cohort were found to be similar to that of an age, sex, and body mass index-matched subsample of controls taken from the 2017-2018 National Health and Nutrition Examination Survey.

The study also found that patients with LCFAOD did not have a difference in kcal/kg compared to healthy controls. Patients with LCFAOD consumed a similar percentage of kcals of protein to the control group but consumed more carbohydrates and fewer total fats.

A total of 32 patients with LCFAOD were recruited for the study, ranging in age from 7 to 64 years. One participant was excluded due to lack of consent for secondary analysis, and 2 participants did not return urine samples used in the study to estimate energy expenditure resulting in a total of 29 participants’ data being included in the analyses.

The participants’ REEs were measured using indirect calorimetry after an overnight fast. The TEE was measured using a doubly-labeled water method. The estimated REE values were computed using a variety of BMR-prediction equations including those Schofield, Harris-Benedict, and Mifflin St. Jeor. Estimated TEE values were calculated using the DRI estimated energy requirements equations.


DeLany JP, Horgan A, Gregor A, Vockley J, Harding CO, Gillingham MB. Resting and total energy expenditure of patients with long-chain fatty acid oxidation disorders (LC-FAODs). Mol Genet Metab. Published online January 23, 2023. doi:10.1016/j.ymgme.2023.107519