Background

The FTO gene (rs9939609) is associated with higher body weight, possibly via increased caloric intake. We therefore evaluated whether genotypic differences in intake are evident prior to obesity onset by examining associations among genotype, intake, and BMI-Z in 5-10y non-overweight children using preliminary data from an ongoing study.

Methods

At baseline, youth were genotyped and a subset completed a multi-item ad libitum laboratory lunch meal. Height and weight were measured at baseline, 6m, and 1y. ANOVAs were used to test genotypic differences in intake and BMI-Z change.

Results

Youth (n=156, age 8.3±1.5y, BMI-Z 0.29±0.99, 49% female) were genotyped and a subset (n=98) completed test meals. Genotypic distribution was 19% AA, 47% AT, and 35% TT. At baseline, there was no difference in genotype distribution between youth with BMI above and below the 50th percentile. There was a non-significant genotype effect on multi-item meal intake (AA=821±296 kcal, AT=765±275 kcal, TT=678±205 kcal, p=.11). AX (785±281 kcal) ate significantly more than TT (678±205 kcal, p=.05). Controlling for fat free mass, there were no genotype effects on intake (p’s≥.30). Seventy-eight youth attended 1y visits. There was no difference in BMI-Z change among genotype groups (p=.24). In exploratory analysis, there was a significant genotype effect on intake in youth with baseline BMI above the 50th percentile (AA=897±58 kcal, AT=712±40 kcal, TT=702±42 kcal, p=.02), controlling for fat free mass. In youth with baseline BMI above the 50th percentile, AA had marginally greater BMI-Z gain compared to other groups (p=.08). These associations were not found in youth with BMI below the 50th percentile (p’s>.60).

Conclusions

Among children with BMI above the 50th percentile, those with AA genotype consume more calories at a multi-item laboratory meal and have marginally greater BMI-Z gain compared to AT and TT. These data suggest that AA youth with BMI above the 50th percentile may be at greatest risk for excess weight gain.