Objective　The present study examined the effects of Kaempferia parviflora extract（KPE） supplementation on energy metabolism and fat utilization rate in healthy subjects.
Methods　A randomized double-blind crossover study was conducted to assess the effect of a single oral intake of KPE on 15 healthy volunteers. Respiratory quotient（RQ）and parameters of heart rate variability were determined during constant low-intensity exercise（30％ of maximal oxygen consumption）after intake of the test food.
Results　After excluding outliers, the number of subjects analyzed was twelve. There were no significant differences in any of the parameters of heart rate variability between the placebo and KPE groups. Single oral intake of KPE significantly attenuated the increase of RQ by exercise compared to the placebo.
Conclusion　Our data suggest that a single oral intake of KPE increases the rate of fat utilization during exercise at a constant intensity, and is a potential tool for the prevention and improvement of obesity and metabolic syndrome.