The effects of rapid growth on body mass index and percent body fat: A meta-analysis

Rapid growth in childhood and obesity are highly prevalent in congenital deficiency infants, but the associations between them remain controversial. This meta-analysis was performed to explore the effects of rapid growth on body mass index (BMI) and percent body fat (PBF), and to clarify potential confounders.

A systematic search was performed using electronic databases including EMBASE (1985 to July 2019) and Medline (1966 to July 2019) for English articles. China National Knowledge Infrastructure Chinese citation database (CNKI) and WANFANG database were used to search articles in Chinese. Reference lists were also screened as supplement. All relevant studies that compare BMI or PBF between rapid group and control group were identified. The definition of rapid growth should be clearly specified. Means and standard deviations/95% confidence intervals (CIs) of BMI and PBF should be available. Relevant information was extracted independently by two reviewers. Study quality was reassessed using the Newcastle-Ottawa Scale. Publication bias and heterogeneity were detected. The random effect model was adopted for combined and stratified analysis.

About the effect of rapid growth on BMI, seventeen researches (4473 participants) involving 49 comparisons were included. Pooled analysis showed rapid group had higher BMI of 0.573 (95% CI, 0.355 to 0.791; P < 0.001). Stratified analyses revealed that catch-up weight gain, follow-up age >6 years old, rapid growth duration >2 years, full-term, comparing rapid growth SGA infants with control SGA infants, and from developed and developing countries, would all lead to higher BMI in rapid groups. About the effect of rapid growth on PBF, eleven researches (4594 participants) involving 37 comparisons were included. Pooled analysis showed rapid group had higher PBF of 2.005 (95% CI, 1.581 to 2.429; P < 0.001). Subgroup analyses suggested that catch-up weight gain, follow-up age ≤6 years old, rapid growth duration >2 years, full-term, comparing rapid growth SGA infants with control AGA infants, and participants from developing countries, would lead to increased PBF in rapid groups.

Rapid growth has a positive correlation with BMI and PBF. However, stratified analyses show that it is catch-up weight gain that lead to higher BMI and PBF, but not catch-up growth. In addition, rapid growth have long-term effect on BMI and short-term effect on PBF. Rapid growth duration longer than 2 years may increase the risk effect of rapid growth on BMI and PBF. But given that rapid growth would induce multiple health outcomes apart from BMI and PBF, the benefits and risks of rapid growth must be carefully considered and weighted.