Breast-feeding may help mothers reduce the risk of obesity later in life, according to a study of 740,000 post-menopausal women in the U.K.
For every six months women breast-fed, their body mass index was 0.22, or 1 percent, lower, even decades after giving birth, according to the research, which was published today in the International Journal of Obesity. The observation was made across socioeconomic groups and regardless of the number of children the women had.
While the body-fat measure, known as BMI, was higher in women who gave birth to more children, it was lower in mothers who breast-fed than in those who hadn't. Breast-feeding has also been found to reduce the risk of childhood obesity. More than 1.4 billion adults globally are overweight and at least 500 million of them are obese, with a BMI of 30 or more, according to the World Health Organization.
"A 1 percent reduction in BMI may seem small, but spread across the population of the U.K., that could mean about 10,000 fewer premature deaths per decade from obesity-related conditions, such as diabetes, heart disease and some cancers," Valerie Beral, co-author of the study and director of the Cancer Epidemiology Unit at the University of Oxford, said in a statement.
The study, funded by Cancer Research UK and the Medical Research Council, used data from the Million Women Study, which investigates how reproductive and lifestyle choices affect women's health. Of the 740,000 participants in today's study, 88 percent had had at least one child and 70 percent of those women had breast-fed for an average of 7.7 months.
The average age of the women in the study was 57.5 and the mean BMI was 26.2. BMI is a measure of body fat calculated using a person's height and weight. A person whose BMI is between 25 and 30 is considered overweight, while one whose BMI is 30 or greater is obese.
While the exact reason for the lower BMI years after giving birth wasn't studied, breast-feeding may set mothers on a healthier trajectory that is long-lasting, Beral said. It seems to be "a very simple way of having a persistent slight reduction," she said.