Thermogenic response to food: intra-individual variability and measurement reliability.
The objective of this study was to assess the reliability and variability of the thermogenic response to food (TRF) in healthy adult subjects. Eight healthy adults (4 men, 4 women) participated in three sets of measurements of TRF, evaluated by indirect calorimetry with a ventilated hood system during 6 hours after a standardized meal. The reliability of TRF measurement was estimated using a one-way analysis of variance with repeated measurements. After the 6-hour period of measurement, the within-subject coefficient of variation for TRF was 10.7%, while the between-subject variability was twice as high (24.1%, p < 0.01). The overall reliability estimate of TRF was acceptable (RE > or = 0.80) after a single measurement which lasted at least 6 hours postprandially, while duplicate and triplicate measurements reached a similar degree of reliability in 3 hours. These results suggest that intra-individual variability contributes little to the variability commonly seen in TRF studies, provided that the measurement period is at least 6 hours.