Basal metabolic rate in monozygotic and dizygotic twins

The basal metabolic rate (BMR) was determined in 14 pairs of monozygotic (MZ; 11 females, 3 males) and 12 pairs of dizygotic (DZ; 10 females, 2 males) twins, with mean ages of 22.7 and 26 years. Zygosity was confirmed using DNA fingerprinting. When BMR was expressed as kJ/d, kJ/kg/d and kJ/kg FFM/d significant intra-class correlation coefficients were observed in the MZ twins of 0.82, 0.79 and 0.85, respectively. The DZ twins showed much lower intra-class correlations coefficients of 0.1, 0.07 and -0.04. Although the results of the study suggest a likely genetic component to the variation in BMR, they should be interpreted with caution as heritability estimates vary with the method of calculation. These will be critically discussed in the paper.