We’ve all heard the news that breastfeeding is the healthiest choice when deciding on how to feed our infants. Now there is one more reason to nurse your baby: A  conducted over the past 30 years shows that successfully preventing obesity later in life may start with breastfeeding. One-fifth of all American children are obese, and the problem may start as early as infancy. Multiple studies have suggested that breastfeeding protects infants from both childhood obesity and obesity later in life as compared to formula feeding. Also, according to the research, the longer a baby is breastfed, the lower the risk of being overweight and obese later in life.

The World Health Organization (WHO) aims to increase the number of babies who are breastfed worldwide and encourages exclusive breastfeeding for the first 6 months, after which time solid foods can be introduced gradually. In fact, one study in this review suggested that introducing solids early in the infant’s life – before 6 months – did not protect against later obesity.

How might breastfeeding protect from obesity throughout childhood and later in life? Researchers have proposed a few explanations. First, after studying feeding patterns, some have discovered that increased breast milk supply, from using a breast pump, for example, does not increase the volume the baby will take. In other words, breastfed infants appear only to take the amount of nourishment they need. Mother’s milk is the perfect source of nourishment for the baby, providing the nutrients an infant needs and changes in composition as the child grows and develops. Likewise, formula-fed babies drink a greater volume of formula in later infancy, which may indicate bottle-feeding does not promote the same degree of self-regulation observed in breastfed babies.  These early differences in feeding behaviors may account for later eating patterns that can contribute to excess calorie consumption and weight gain over time.

Second, while more investigation is needed, researchers are learning more about a number of hormones related to energy metabolism that are found in breast milk but are absent from formula. Ghrelin, a hormone which is produced in the stomach, stimulates the appetite, while leptin is a hormone that signals the feeling of fullness. Formula-fed infants have been found to have higher levels of ghrelin and lower levels of leptin, compared to breastfed infants. Other hormones, including resistin, obestatin and adiponectin are also thought to affect growth and development. In fact, a suggests that these five hormones found in breast milk may be protective against obesity later in life.

Breast milk is also lower in protein than formula and cow’s milk. Some studies show excess protein, beyond that provided by breast milk, may relate to obesity in infancy.

Study results continue to be consistent and provide strong evidence to support the benefits of breastfeeding over formula feeding for health, growth and development, as well as obesity prevention. Pediatricians use growth charts to monitor children’s growth patterns regularly. You should discuss the results with them to determine whether trends in your child”s growth pattern may raise a red flag and should be addressed. The earlier obesity is tackled, the more effective intervention is likely to be.