Infant Weight Gain May Predict Obesity

By Salynn Boyles
WebMD Health News Reviewed by Louise Chang, MD

June 9, 2008 -- There is growing evidence that babies who gain weight rapidly during the first few months or years of life may be at increased risk for obesity as they get older.

Three new studies, published in the June issue of the American Journal of Clinical Nutrition, support the hypothesis that early growth is predictive of weight during adolescence or adulthood.

In one of the studies, researchers from the health research organization Institut National de la Sante et de la Recherche Medicale in France followed children from birth to age 5, identifying two critical periods in which early-life weight gain appeared to influence later obesity risk.

The first critical period occurred in the first few months of life and the second occurred after age 2.

"Between these periods, growth seemed to be preferentially directed towards height and not weight," researcher Marie-Aline Charles tells WebMD.

In a separate study from Finland, researchers found little evidence of an obesity link associated with rapid weight gain before the age of 2. But rapid weight gain after the second birthday was found to be a risk factor for obesity later in life.

The study included 885 Finnish men and 1,032 women between the ages of 56 and 70, whose childhood weights and heights were known from medical records.

Rapid weight gain before age 2 was associated with increases in lean mass while rapid gains later in childhood predicted higher body fat in adulthood.

In the third study, rapid weight gain during the first six months of life was found to increase obesity risk later in childhood.

Researchers from London's Institute of Child Health investigated the associations between weight gain during different periods in infancy and later body composition in 105 boys and 129 girls living in the U.K.

The three studies are not the first to link early growth to later obesity.

An analysis of 24 such studies, published in 2005, suggested a link between rapid weight gain before age 2 and obesity later in life.

Obesity prevention researcher Matthew W. Gillman, MD, of Harvard Medical School tells WebMD that rapid weight gain after age 2 or 3 is now generally recognized as a risk factor for later obesity.

He adds that there is "mounting evidence" that the same is true for rapid weight gain in the first few months or even weeks of life, but the link has not been proven.

In an editorial published with the studies, Gillman called for studies to directly address the question.

"All parents want to know, 'How big should my baby be?'" he writes. "Researchers, clinicians and the public health community need to be able to respond not only to that question, but also to the follow-up challenge of what we can do to ensure that babies are the right size."