Characterization of Infant Energy Balance to Optimize Early Life Growth

About This Grant

PROJECT SUMMARY One in four U.S. children enter kindergarten with overweight or obesity, yet the fundamental determinants of infant energy balance (i.e., the interplay of intake and expenditure) are poorly defined. Current reference standards for infant energy intake rely on decades-old and limited data. Our preliminary data demonstrates large errors (mean 16%, up to 71%) in predicted energy needs among 1–3-month-old infants, showing that such standards promote unintentional overfeeding during a critical window of metabolic programming. This highlights the lack of longitudinal energy balance phenotyping studies to understand the drivers of a more positive energy balance, thus, accelerated growth. Here we propose, Characterization of Infant Energy Balance to Optimize Early Life Growth, a first-of-its-kind prospective observational study healthy infants (N=100) longitudinally assessed from one to 12 months of age; at one, three, six, nine, and 12 months. Using gold-standard, rigorously adapted methods for infants, we will objectively assess energy intake (intake-balance method) and quantify free-living total daily energy expenditure (TDEE), sedentary energy expenditure, and physical activity energy expenditure. We will combine these with other physiological measures including biomarkers T3, leptin, and epinephrine, behavioral factors (feeding patterns, milk type, timing of complementary foods, accelerometry) and developmental progression (gross motor milestones) to precisely phenotype infants and identify drivers of growth. The principal aims are to objectively assess components of energy balance throughout the first year of life and compare between those with accelerated and appropriate growth. This is novel because while we propose a prospective study design, we have opportunities to perform retrospective analyses at each three-month assessment to utilize point estimates along each of the three months to predict growth using newly identified drivers. This allows for identification of vulnerable periods for excess growth, such as specific ages or developmental milestones such as the introduction to complementary foods or periods of delayed gross motor achievements. This study will generate the first robust dataset on infant energy balance and its mechanistic underpinnings. By revealing physiological and behavioral drivers of early growth and updating imprecise energy standards, findings will directly inform strategies to prevent youth- onset obesity.