Early infant weight gain, obesity, and adult disease

By Inés Anchondo, Dr PH, RD, LD, CSP

Don’t be alarmed by publications warning that early rapid weight gain creates adult disease. The evidence is flimsy and the interpretations suffer from lack of understanding about normal growth. Follow the division of responsibility in feeding your baby, and ignore these damaging news releases. Some babies are just large, and their large size is healthy. Don’t interfere with your baby’s growth, or you will create the very issues researchers warn about.

Definitions of too-fast weight gain ignore normal growth

None of the definitions consider early weight gain in the context of feeding dynamics and the infant’s longitudinal growth pattern. Distortions in growth may reflect distortion in feeding, which is not evaluated in the studies. The patterns described may also represent normal growth variations, including catchup growth. Definitions include: 

• Weight for age above the 90th percentile at 6 weeks, 3 months, and 6 months of age.¹ 
• A 0.67 z-score² point increase in weight for age in z-score at birth, 2 and 5 years of age.³ This is the most commonly used definition in research studies. 
• A 1.00 or more z-score point increase at 4 months, 12 months, and 7 years.⁴
• A change in weight for age z-score between 8 days and 112 days of age.⁵

“Consequences” are slight to non-existence and based on problematic methodology

While rapid early weight gain doesn’t seem to be a problem, there is a huge problem with sounding the alarm about it. Parent, caregivers, and health professionals may zealously restrict young infants’ food intake in an attempt to keep them from gaining  ‘too much’ weight.

Such problematic methodology includes:

• Using an arbitrary definition of too-fast early weight gain.
• Drawing conclusions about patterns that are shifted but are not abnormal.
• Ignoring other factors that can impact growth patterns.
• Using a variety of follow-up ages and characteristics.  

Rapid early weight gain does not increase adult disease

Researches assert that “too-fast” early weight gain increases the risk of adult diseases such as cardiovascular disease (CVD), high blood pressure, and metabolic syndrome. However, careful interpretation of the studies shows that: 

• Low BMI (not high) associates with higher LDL, and VLDL, used as measures of cardiovascular disease.⁶
• The correlation between BMI at birth and adult BMI is barely significant.⁶ This association could simply reflect genetic inheritance and normal growth patterns.
• The association between too-fast weight gain after birth and high blood pressure is lost after taking adult height into consideration.⁷
• The diastolic blood pressure is somewhat higher, but it is not abnormal.  Even breastfed, rapidly gaining infants show this modest blood pressure increase.⁸

Early “too-fast” weight gain has important positive effects

These positive effects include higher birth weight in the second generation and longer and more successful schooling.^9,10

• Children who weigh more at birth have a greater chance of survival, which is especially important in a developing country.  In a 2004-2005 study in Brazil, Hortaet al. interviewed 848 mothers and 525 fathers to compare parents’ own childhood weight gain with their children’s birth weight. Women who had gained weight faster during their own first 2 years of life have children who are heavier at birth. Men show no association.⁹
• Children with a good start can have a better future. Martorell et al. studied a large number of individuals from five developing countries – Brazil, Guatemala, India, Philippines, and South Africa – to look at the relationship between schooling, birth weight, and childhood weight.  Higher birth weight and higher weight gain during the first 2 to 4 years of life is associated with more schooling and less grade failure.¹⁰

Do no harm

While scholarly analysis of the research shows the consequences of early weight gain to be modest to non-existent, the consequences of sounding the alarm about early weight gain are dire and may create the very problem they are intended to avoid. Parents, caregivers, pediatricians, nurses, and others may zealously restrict young infants’ food intake in an attempt to keep them from gaining “too much” weight. Endangering the child’s nutritional status aside, restricting an infant’s food intake complicates his achieving the developmental tasks of homeostasis and attachment, distorts his eating attitudes and behavior, and undermines his regulating his food intake based on internal cues of hunger and fullness. Growing out of these distortions, some infants’ growth may accelerate, others may falter.

What is a practitioner to do?     

• Obtain accurate measures of weight and length or height, as appropriate.²
• Follow the child’s weight over time and determine the pattern.²
• Identify growth divergence. Consider disruptive influences for each child and correct those disruptions.¹¹
• Recommend parents and caregivers follow Satter’s Division of Responsibility in Feeding (sDOR).