Fourteen Caucasian subjects ( BMI : 22.22.3 kg/m2 , age : 21.42.2 years ) of whom 7 with the COMT ( H ) - genotype and 7 with the COMT ( L ) - genotype were included in a randomized , cross-over study in which EE and substrate oxidation were measured with a ventilated-hood system after decaffeinated GT and placebo ( PL ) consumption .