What are the causes of excessive weight gain in infants?

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Last updated: March 17, 2025View editorial policy

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From the Guidelines

Excessive weight gain in infants is primarily caused by rapid weight gain during the first 6 months of life, which can be influenced by factors such as formula feeding instead of breastfeeding, and can lead to an increased likelihood of overweight during adolescence and adulthood 1. When examining the causes of excessive weight gain in infants, several key factors come into play. These include:

  • Rapid weight gain during the first 6 months of life, which has been identified as a determinant of overweight during childhood and young adulthood 1
  • The introduction of formula feeding instead of breastfeeding, as breastfeeding has been shown to confer a protective effect against the development of overweight in childhood and adolescence 1
  • The lack of control over energy intake in formula-fed babies compared to breastfed babies, which can lead to overfeeding and subsequent weight gain 1 Other potential causes of excessive weight gain in infants may include:
  • Genetic factors that predispose some infants to weight gain
  • Certain medical conditions, such as hypothyroidism or Prader-Willi syndrome
  • Medication side effects However, breastfeeding exclusively for at least 6 months has been identified as a safe and effective intervention for the prevention of obesity in early infancy 1. Parents should be encouraged to follow recommended feeding guidelines and monitor their infant's growth using standard growth charts during regular pediatric check-ups. Establishing healthy feeding practices early, such as recognizing hunger and fullness cues and avoiding food as a primary soothing method, is also crucial for preventing excessive weight gain in infants.

From the Research

Causes of Excessive Weight Gain in Infants

The causes of excessive weight gain in infants can be attributed to several factors, including:

  • Infant feeding practices, such as formula feeding, which has been associated with an increased risk of excess or rapid weight gain compared to breastfed infants 2
  • Nutrient composition of formula and the way it is prepared and provided to infants 2
  • Bottle-feeding at birth and at 3-4 months, and nighttime meals containing formula milk, which have been positively associated with rapid weight gain during the first year of life 3
  • Lack of breastfeeding, as breastfeeding at 3-4 months and nighttime meals containing breast milk have been negatively associated with rapid weight gain 3

Biological Determinants

Biological determinants, such as metabolic programming that occurs early postpartum, may also play a role in excessive weight gain in infants, with weight gain in the first 6 months being especially predictive of later obesity risk 4

  • Infant feeding choice, particularly formula feeding, may program the metabolic profile of the infant, causing a link between early weight gain and later obesity 4
  • Maternal metabolic dysfunction, such as obesity and/or diabetes, may affect milk composition and exert downstream effects on infant metabolism 4

Risk Factors

Several risk factors have been identified, including:

  • Sociodemographic characteristics, parental weight or health status, infant feeding or health behaviours, which can increase the risk of excess weight gain in infants 5
  • Nutrition- and feeding practice-related factors, such as bottle-feeding and formula milk given at night, which have been positively associated with rapid weight gain during the first year of life 3

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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