Reductions in the energy content of meals served in the Chilean National Nursery School Council Program did not consistently decrease obesity among beneficiaries.

In 2001, the Chilean National Nursery Schools Council Program reduced by 10% the energy content (approximately 418.7 kJ) of meals served to children to reduce obesity. We assessed the impact of this measure on obesity and stunting among beneficiaries 2-5 y old. The energy reduction was staggered over 3 y, allowing for a quasi-experimental design involving early (2001), mid (2002), and late (2003) intervention groups. Routine anthropometric measurements (approximately 64,000/y) taken from 1996-2005 were obtained from registries; obesity (BMI-for-age Z-score > or = 2 SD) and stunting (height-for-age Z-score < or = 2 SD) were defined using the 2006 growth standards. Segmented regression analyses were conducted by intervention group to contrast pre- and postintervention trends. Overall, obesity was high (15.9%), with levels consistently higher in fall and winter as reported in other studies. Preintervention obesity trends increased in the early group (P = 0.001) but decreased in the late intervention group (P = 0.02). The impact of the energy reduction on obesity was inconsistent, with reductions in the early group (P < 0.01) but with no change in mid and late intervention groups (P > 0.05). Stunting prevalence was almost as low as in the growth standard (3.2 vs. 2.3%) and decreased preintervention in all groups (P < 0.05). Stunting prevalence increased postintervention (P < 0.05) in all but the late intervention group, where there was no change. Despite a robust design and the ability to detect small seasonal changes in obesity, our analyses showed that the 10% energy reduction did not consistently decrease obesity. The intervention may have slowed improvements in linear growth, but concern is tempered by the near absence of growth failure.