If you give your baby formula, studies show that your baby is at greater risk of obesity—and that risk is related to the amount of formula he receives. The more formula, the higher the risk—and vice versa. Researchers haven't figured out exactly why this is the case; some theorize that bottle-feeding encourages overfeeding, while others suggest it is because formula doesn't have the specific factors in the mother's milk that help to regulate the baby's appetite. Most experts agree that risk is affected by a combination of these factors.
According to the Centers for Disease Control and Prevention (CDC), studies show that breastfeeding reduces the risk of a child becoming overweight. Children who breastfed (any amount) for nine months had a 30 percent reduced risk compared to those who exclusively formula-fed.
Exclusive breastfeeding seems to offer greater protection than a combination of breastfeeding and formula-feeding. A study of Canadian schoolchildren found that both those who were formula-fed and those who received a combination of formula and breast milk were at higher risk of overweight and obesity than those who received only breast milk.
This protection from the risk of becoming overweight doesn’t stop in childhood. Although long-term studies are limited, the CDC concludes that the protection breastfeeding offers against one’s risk of becoming overweight extends into adolescence and even into adulthood. A study of data from the Western Australian Pregnancy Cohort, covering infancy to age 20, found that breastfeeding until 6 months of age protected against increased risks of obesity in childhood, adolescence, and young adulthood.
Tips for reducing your baby's risk of obesity
Not all formula-fed babies are overweight, just as not all breastfed infants are a healthy weight. The following tips—most of which are applicable to all babies, regardless of how they are fed—will help you reduce your baby’s risk of obesity:
- Pay attention to your baby’s signals, including hunger cues and signs of fullness. If you are bottle-feeding, stop feeding when your child seems less interested, even if there is breast milk or formula left in the bottle.
- Use paced bottle-feeding. Hold your baby upright, and stimulate his rooting reflex. Wait for your baby to draw the bottle nipple into his mouth, and encourage frequent pauses while feeding (suck-suck-suck-pause). (For more bottle-feeding tips, read this.)
- If using a bottle, choose the right size. Using an oversized bottle may contribute to overfeeding. A large study published in Pediatrics found that using a large bottle (6 ounces or larger) in early infancy contributed to rapid infant weight gain, possibly leading to later obesity among formula-fed infants.
- Introduce complementary or solid foods no sooner than 6 months of age, unless medically indicated. Higher risk of obesity may be linked to the early introduction of solid foods. This 2020 review goes into great detail on the pitfalls of early complementary feeding.
- Limit fruit juice. Babies don’t need juice; fresh fruit is a better source of nutrition than its liquid counterpart. If you choose to give your baby juice, wait until he is at least 6 months of age and give only small quantities of 100-percent juice with no sugar added, and limit the serving to no more than 4–6 ounces per day. Consider diluting the drink to half-water and half-juice.
- Feed your baby healthy meals that include iron-rich foods, in addition to a variety of fruits and vegetables. (MyPlate.gov provides guidance.) Be a good role model by eating healthy meals and engaging in regular physical activity.
For more about how your child’s pediatrician will measure his growth over time, read this.