RESTING METABOLIC-RATE AND DIET-INDUCED THERMOGENESIS - A METHODOLOGICAL REAPPRAISAL

The variability in resting metabolic rate (RMR). diet-induced thermoge nesis (DIT), and fuel utilization rates as well as the impact of sever al factors on RMR and DIT were assessed in several studies with a tota l of 103 males and females. The intraindividual CV of RMR and respirat ory quotients was 5-6%. The intraindividual variability in DIT and fue l utilization rates was substantially higher. RMR did not change from morning to afternoon. The menstrual cycle phase did not affect RMR and DIT. DIT after mixed meals of 1.3-2.6 MJ could be assessed with good accuracy in 3 h. It is concluded that the low reproducibility of DIT i mplies that sample sizes of < 10 individuals with one measurement per subject and per treatment have power levels < 80% of assessing true, r elatively large (50%) treatment effects or between-group differences i n DIT.