Solid food introduction: Does age actually impact obesity risk?

It is generally accepted that feeding infants solids foods before 4 months of age might lead to obesity, and the American Academy of Pediatrics (AAP) even cites weight gain as a risk factor of early feeding.

However a new study from the Centers for Disease Control and Prevention (CDC) reveals that, when gestational age, gender, maternal characteristics, and food choices are considered, there is really no greater risk for obesity in children who are fed solids at 4 months of age compared to the recommended 6 months of age.

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The study, published in Childhood Obesity, reveals that, despite a number of studies linking early solid food introduction to childhood obesity, the age at which solid foods are introduced does not appear to have a significant impact on obesity later in childhood.

Chloe M Barrera, MPH, of the division of nutrition, physical activity, and obesity at the CDC, says previous studies were inconsistent on whether early introduction of solid foods before 4 months was truly tied to childhood obesity, and her team conducted this larger-scale study to try and find an answer.

“In our analysis of more than a thousand babies followed through the first year of life and contacted again at 6 years, we did not find this association,” she says.

 The team at CDC used data from 1181 infants enrolled in the Infant Feeding Practices Study II and Year 6 Follow Up studies to identify a possible correlation between the time at which solid foods were introduced and development of obesity at age 6 years.

The study revealed that childhood obesity, which was 12% overall among the study sample, was more likely in children who were introduced to solid foods before 4 months of age-with 15.4% of the children categorized as obese- compared to those who were introduced to solid foods between 4 and 6 months of age-with 9.9% obese. However, the study authors note that when other variables based on the individual child and lifestyle were considered, there was no significant difference in obesity rates in children who were introduced to solids at 4 months versus 6 months. Researchers also didn’t find any correlation between early formula or breast feeding and subsequent obesity.

According to the report, more than 8% of 2- to 5-year-olds, and 17% of 6- to 11-year-olds are obese and therefore at risk for chronic health problems. However, the study authors note that there are many contributing factors to childhood obesity, and no single factor-even infant feeding practices-can explain the path to obesity.

Early introduction of solid foods in infancy has been identified as one possible cause of childhood obesity, and the AAP reports as association between feeding solid foods before 4 months of age with increased weight gain and adiposity. The AAP now recommends holding off on solid food until 6 months of age, but a 2013 report from researchers at the CDC revealed that many parents do not heed that advice.

NEXT: What does this new evidence mean?

According to the CDC’s 2013 report, about 40% of infants are introduced to solid foods before 4 months of age. Most of those infants are formula-fed or fed with a combination of breast milk and formula (52.7% and 50.2%, respectively) and 24.3% were breastfed infants. Most of the parents cited age; perceived readiness and hunger in the infant; or physician advice to justify early solid food feeding, according to the report.

The new report states that while most groups agree that introduction of solid foods before 4 months of age is too soon, there is some debate about the consequences of introduction in the 4- to 6-month range. Other studies have revealed correlation between introduction of solid foods at 4 months and childhood obesity, but few were large, quality studies.

The CDC team suggests that other studies have revealed a correlation between early solid food feeding-particularly among formula-fed infants-where theirs did not because breastfed infants are better at self-regulating their intake by decreasing breast milk intake as additional foods are introduced. Formula-fed infants, on the other hand, may be given solid foods in addition to formula, rather than as a substitute. Formula-fed infants are also more likely to be fed formula until the bottle is empty, rather than taking cues from the infant to complete the feeding, according to the report.

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The report authors note that, although they didn’t identify an association between the timing of solid food introduction and childhood obesity, optimal feeding practices should still be promoted for all infants. This includes supporting exclusive breastfeeding for the first six months and continued breastfeeding for at least the first year, with complementary foods introduced as appropriate.

The AAP recommends beginning solid foods when the infant can hold his or her head up with good control, and when they indicate interest in table foods or open their mouths as food is offered. Weight is also a good indicator of readiness, according to AAP, and most infants are ready for solids when they double their birth weight and/or weigh above 13 pounds. Caregivers should also monitor the infant’s ability to swallow, noting whether the infant is able to move the food to the back of its mouth and swallow.

Barrera says while there was no correlation to childhood obesity as a result of early solid food feeding, there is still strong evidence supporting later feeding for a number of reasons.

“Regardless of an association with obesity, it is still not recommended to introduce solid foods to babies too early,” she says. “The AAP recommends solid foods should be introduced at about 6 months.”

Limitations of the study included possible variation by using weight and height measurements submitted by parents, and the fact that the CDC sample was not nationally representative.