Background: Nutrition during early life is of fundamental importance for optimal health during childhood as well as later in life. The prevalence and the severity of obesity in children and adults are presently increasing at alarming rates world wide, which is of great concern as obesity is associated with increased morbidity. Available systematic information regarding body composition development during childhood is presently very limited and there is a need for accurate methods for determining body fatness in young children. The doubly labelled water (DLW)-method is non-invasive and measures total body water (TB W) and total energy expenditure (TEE) of humans during true free-living conditions. Estimates of TB W can be used to assess body fatness. Previous studies in young children below 3 years of age have shown low values for TEE, indicating that current recommendations for dietary energy intake are too high. However, in most of these studies the children were below 6 months of age, and no Swedish studies cover the age range 7-36 months of age.
Subjects & Methods: TEE and TBW were measured by means of the DLW-method in healthy Swedish children at 9 (n=30) or 14 (n=29) months of age. Total body fat (TBF) was calculated from TBW and body weight using the body water dilution (BWD)-method. When expressed in percent of body weight, these estimates (% TBF-BWD) represented reference values for body fatness. Body fatness was also measured using the skin fold thickness technique (% TBF-SFT) and body mass index (BM I). The children were ranked and grouped into five groups with increasing levels of body fatness using %TBF-BWD, %TBF-SFT and BMI, respectively.
Results: TEE was 323 ± 38, 322 ± 29, 313 ± 23 and 331 ± 28 kJ/kg/d for 9-month-old girls and boys and 14-month-old girls and boys, respectively. BMI, %TBF-SFT and %TBF-BWD for all children were 17.5 ± 1.6, 27.8 ± 3.7% and 29.1 ± 4.4%, respectively. %TBF-BWD minus %TBF-SFT was = 1.35 ± 4.06% (n=59). By measuring %TBF-SFT or BMI, about 35% of the children could be classified in the correct group with respect to body fatness. Serious misclassification was more common for %TBF-SFT (29%) than for BMI (17%). There was a significant inverse linear relationship between PAL and %TBF-BWD (r = -0.81, P<0.00l, n=59).
Conclusions: The requirements for dietary energy of a group of Swedish children, 9 and 14 months of age, were 15-20% lower than indicated by current recommendations. In the group of children studied, BMI as well as the skinfold technique were poor tools for classification of body fatness. The skinfold technique produced inaccurate and imprecise estimates of body fatness. It can be speculated that the relationship between PAL and %TBF-BWD indicates that children with a high percent body fat are more likely to be in a state of positive energy balance, which would favour fat retention, possibly establishing a vicious cycle early in life leading to further accumulation of fat in the body.
Linköping: Linköpings universitet , 2003. , 33 p.
2003-02-14, Lärosal 1, Hälsans hus, Universitetssjukhuset, Linköping, 09:00 (Swedish)