The overall goal of this project is to conduct a sub-analysis of the primary study data to identify factors related to the magnitude of change from baseline with C7 supplementation. I will analyze the data by LC-FAO disorder diagnosis and compare those supplemented with triheptanoin (C7) versus trioctanoin (C8) to determine if any LC-FAOD had a greater response with C7 supplementation compared to C8 supplementation. Age at initial presentation was recorded and will be used as an estimate of disease severity. In the original study, all subjects were counseled to consume 20% of their estimated total energy needs daily from C7 or C8 oil for a 4-month period while following a diet low in long-chain fats. Adherence was assessed by multiple 3-day diet records and measurement of unconsumed daily oil at the end of the study. I hypothesize that participants with a more severe phenotype and those who consumed more of the prescribed C7 will have shown a greater response.