Increased Formula Feeding during Early Infancy leads to Increased Weight Gain during Later Infancy

Energy-dense Formula Milk can Never Fulfill Breastmilk’s Wellness & Nutrition

East or West Breast Milk is the Best

Variety might be the spice of life but there is also the fact that too much of anything is good for nothing. We need choices but having our hands full on these choices also paves way for a state of confusion. This is applicable to food choices too. Previously, one would have never thought of experiencing different cuisines at the snap of our finger but now we get to enjoy Italian, Mexican and Thai food sitting in the comforts of our house. Likewise, right after childbirth a newborn’s only source of food was breastmilk and there was no discussion beyond it. But now, we have come up with different alternatives for nature’s gift to our lovely babies quoting different reasons. The world has insisted on exclusive breast milk feeding right until the infant’s sixth month owing to aplenty benefits such as increased immunity, nutrients and reduced risk of obesity/overweight still there are many who ignore all these benefits and continue feeding the infant with formula milk or likewise. There might be valid reasons for switching over to formula milk but it is also essential that we understand the downsides of the same.
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Obesity and overweight issues don’t exist only among the adult population but is well-established in the child and infant population as well. Obesity during early years is a crucial health issue that’s of immense importance as they have a number of adverse health consequences that’s associated with increased mortality and morbidity risk in early adulthood. There is rapid weight gain and growth during early stages of infancy and those kids who gain more weight during infancy are at an increased risk of becoming obese during early childhood years or even later in life. There are those of you who now wonder how on Earth can an infant become obese when his/her only source of food is milk. You are right but the risk of obesity crops up from the very fact whether the source is breast milk or formula milk as such feeding patterns are the ones that affect growth and development in infancy. During the last decade or so researchers have vigorously studied different feeding patterns, their impact and have also learnt how different infant feeding practices impact health in childhood and beyond. The most important of them is the relationship between early infant feeding and obesity risk. We do have studies showing that formula milk leads to more weight gain than breast milk but we don’t have many that focus on the differences in the growth and risk of overweight in infants fed with different types and volume of milk during early infancy.

Formula Milk & its High Energy Density
A systemic review concluded that formula-fed infants have a 1.2 to 9.5-fold higher energy intake and a 1.2 to 4.8-fold higher protein intake that breastfed infants in the first week of life. The reason being the higher energy and protein content of formula milk and higher volume of consumption all of which contribute to greater weight gain in formula-fed infants compared to breast-fed infants during early infancy. The main difference in early weight gain between formula-fed and breast-fed infants is due to the differences between formula and breast milk in both composition and volume of intake of colostrum. The study elaborated below investigates the association between volume of formula milk consumed at 3 months of age and changes in body weight and length at 3 time points during the first year and also compares the risk of obesity due to differences in volume of milk consumption.

Chinese Systemic Study
1093 healthy neonates were selected for the study and information on maternal characteristics such as age, education, pre-pregnancy weight and height, occupation, health condition, delivery and infant characteristics including sex, gestational age, mode of delivery and birth weight and length were noted down. All the 1093 infants were healthy, singleton, full-term infants of which 587 were boys and 512 were girls. Data was collected at 3, 6 and 12 months of age of the infant. Feeding practices were categorized based on the volume of formula milk consumed at 3 months of age based on the answers to 2 questions: “How many times was your child fed infant formula?” and “How much formula milk does your child usually intake at each feeding?” The research took place in China and according to the Chinese infant feeding recommendations the volume of formula milk consumed was segregated as higher (840 ml or more) or lower (less than 840ml) consumption as the 3-month-old infant consumed 140 ml of formula milk 6 times/day for a total of 840 ml/d. Three types of feeding groups were identified: breast milk feeding (BM, no formula milk) which included 610 infants, lower-volume formula milk feeding (LFM, <840 ml formula milk/d) that included 363 infants and higher-volume formula milk feeding (HFM, ≥840 ml formula milk/day) that included 120 infants. Breast milk feeding included exclusive feeding of breast milk without other liquids or solids with the exception of vitamin and mineral supplements or medicines. Formula milk feeding included feeding of any formula milk with or without breast milk and was categorized into LFM and HFM depending on the quantity of milk consumed per day.

Solids were introduced to nearly 63.7% infants before 6 months of age, almost 51% breast-fed infants were females and the numbers were more than that of the LFM infants (42.4%) or HFM infants (38.3%). Weight-for-length z score (WLZ) and BMI-for-age z score (BAZ) were calculated and was classified as greater body weight (1SD<WLZ<2SD) and overweight (WLZ>2SD) respectively. Results showed that:

1. There was no difference in birth weight and length between any of the feeding groups and average values of body weight and length at three time points were greater in infants in the HFM group than those in the BM group. But there was no significant difference between infants in the LFM and BM group except at 12 months of age.
2. Difference in WLZ between HFM and BM was significant only at 12 months of age same as the difference between the LFM and BM infants.
3. Difference in BAZ was significant both at 6 and 12 months of age between HFM and BM infants but significant only at 12 months of age between LFM and BM infants.
4. Infants both in LFM and HFM showed similar changes in WLZ and BAZ compared to BM infants at 3 months of age. Between 3 and 6 months LFM infants showed higher WLZ gain and BAZ gain than BM infants.
5. HFM infants showed higher WLZ gain and BAZ gain than BM infants. From 6-12 months of age, WLZ and BAZ changes were stable in the LFM and HFM group but the BM group had less WLZ and BAZ gains than the other two formula groups.
6. LFM consumption was not associated with higher body weight and weight gain. HFM consumption was associated with higher body weight and overweight at 6-12 months of age. HFM-fed infants were 1.60-fold times at a higher risk of greater body weight than BM-fed infants at 6 months. HFM-fed infants were 1.55-times at an increased risk of greater body weight and 2.13-times at an increased risk of overweight than BM-fed infants at the age of 12 months.
   
   

This study clearly shows that infants who consumed higher volumes of formula milk at the age of 3 months gained more body weight and length later in infancy than breastfed infants. Those infants who consumed higher volumes of formula milk were at an increased risk of greater body weight and overweight. Hence, it is suggested that higher intake of formula milk is avoided during early stages of infancy to avoid risk of weight gain and obesity during later stages of infancy and childhood.

Longitudinal Study on Bottle Milk Consumption
A longitudinal study researched not only on the type of milk consumed by infants but also on the mode of consumption on 3000 infants who were followed right from birth up to 1 year of age with 10 postnatal questionnaires mailed at monthly intervals. Weight measurements were reported on the 3-, 5-, 7- and 12-month surveys. In every questionnaire provided to mothers they were asked how often they fed breastmilk, pumped breastmilk, formula milk or other types of milk in the past 7 days and based on the answers infants were classified into six milk feeding categories: breastfed only, breastfed and human milk by bottle, breastfed and nonhuman milk by bottle, human milk by bottle only, human and nonhuman milk by bottle only and nonhuman milk by bottle only.

Results showed that compared to infants who were only breastfed those infants fed by bottle gained 71 or 89 g more per month when fed nonhuman milk only or expressed human milk only but gained only 37 g more per month when fed both expressed breast milk and nonhuman milk. Infants fed both breastmilk and formula milk using a bottle gained 45g more per month. For every 10% increase in bottle feeding infants gained 8 g more per month among those who received at least two-thirds of their feedings with breastmilk. This study clearly shows that the type of milk and also the mode of milk delivery strongly affects the weight changes in infants.

In an ideal scenario, the energy content of formula milk should be equal to the energy content of breast milk but most of the commercially available formulas have an energy density of around 67 kcal/100 mL that’s evidently more energy than contents of early breast milk (at 5 weeks it is 57.4 kcal/100ml and at 11 weeks it is 59.8 kcal/100 ml). Apart from being a rich source of macronutrients and energy-dense formula milk is also consumed more in quantities. While breast-fed infants receive limited breastmilk (as supply is restricted) during the first two days of life mothers who feed formula milk encourage the child to finish the bottle despite signs of fullness expressed by the newborn. Also, while protein content of colostrum is extremely high the nutrient decreases as weeks pass by. Whereas, formula milk has 5-times more protein and these infants consume 5-fold high protein quantities during their first two weeks of life compared to breast-fed infants and this leads to faster weight gain in formula-fed compared to breast-fed infants. Breastfeeding is definitely the best approach for optimal nutrition in infants. Formula milk can never match the goodness of natural breast milk but it is necessary to continue researching to replicate the benefits and composition of breast milk as much as possible in formula milk too.

References
Early Feeding of Larger Volumes of Formula Milk is Associated with Greater Body Weight or Overweight in Later Infancy: https://nutritionj.biomedcentral.com/articles/10.1186/s12937-018-0322-5

Risk of Bottle Feeding for Rapid Weight Gain During First Year of Life: https://jamanetwork.com/journals/jamapediatrics/fullarticle/1151630
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Is the Macronutrient Intake of Formula-fed infants Greater than Breast-fed Infants in Early Infancy? https://www.hindawi.com/journals/jnme/2012/891201/

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