Background: Previous studies have suggested that sex may be a factor influencing basal metabolic rate (BMR) in adults and school age children. However, few data are available about the effects of sex on BMR in pre-school children. In the present study, we investigated whether sex differences contribute to variations in BMR in pre-school age children.
Methods: Measurements were made on thirty children aged 2-6 years (14 male and 16 female). Measurements were taken of height, age, weight, and total body composition, which was determined using both dual-energy X-ray absorptiometry (DXA) and deuterium dilution. The DXA was also used to determine body composition in different regions of the body. BMR was measured by indirect calorimetry.
Results: We found no significant sex differences with respect to age (F = 0, p = 0.998), weight (F = 0.02, p = 0.884), height (F = 0.33, p = 0.570), and body mass index standard deviation score (F = 0.51, p = 0.480). In addition, no significant difference was found between boys and girls for total fat free mass (FFM) (F = 1.30, p = 0.265) and fat mass (FM) (F = 3.16, p = 0.090) measured by DXA, and total FFM (F = 0.79, p = 0.380) and FM (F = 3.38, p = 0.080) obtained by deuterium dilution. There was no significant difference between pre-school boys and girls for BMR (F = 0.16, p = 0.690). In a multiple regression analysis, only log weight was significantly associated to BMR. The explain variation was 75.3%.
Conclusion: In conclusions we found no significant differences in body composition between pre-school boys and girls and no sex effect on BMR in this age group.