Breastfeeding for a year or longer protects infants against obesity in later life.
Obesity is a condition in which a person has too much body fat. Having obesity increases a person’s risk for many chronic diseases, including diabetes, heart disease, cancer, and others. New research suggests that breastfeeding for a year or longer protects infants against obesity in later life.
Breastfeeding is the biologically superior way to feed an infant. The American Academy of Pediatrics recommends exclusive breastfeeding for the first six months of an infant’s life and then continued breastfeeding while introducing age-appropriate foods until an infant is 12 months old or older. This provides the infant optimal nutrition and immunity while supporting growth and development.
To model short-term versus long-term breastfeeding in humans, the investigators weaned one group of rat pups at three weeks of age (typical weaning time) and another group at four weeks of age (delayed weaning time, comparable to a year or more in humans). Once the animals were weaned, half of each group were fed a normal diet, and half were fed a high-fat diet until they reached adulthood. The investigators measured the animals' bodyweight, analyzed their body composition, and measured their energy expenditure.
They found that rats that ate a normal diet and were weaned at the typical and delayed times did not differ in terms of bodyweight in adulthood. But rats that had a delayed wean time and were fed a high-fat diet were leaner than those that were weaned at the typical time and fed a high-fat diet. The delayed rats also had higher energy expenditures and more active brown fat, a type of fatty tissue involved in thermogenesis, or heat production. The delayed rats' brown fat contained higher quantities of various proteins involved in thermogenesis, including fibroblast growth factor 21 (FGF21). FGF21 activates neurons in the brain involved in metabolic regulation.
These findings suggest that prolonged breastfeeding protects against obesity in later life, likely mediated by the influence of FGF21 on metabolic regulation. Learn more about the beneficial effects of breastfeeding for both infants and mothers in our overview article.
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