Exclusive breastfeeding tied to greater weight loss in mums

A longitudinal study from KK Women’s and Children’s Hospital (KKH) shows that women who exclusively breastfed at 6 and 12 months postpartum are at a lower risk for substantial postpartum weight retention (PPWR; defined as weight retention of ≥5 kg) compared with those who exclusively formula-fed their infants or practiced a mix of both.

At 6 months postpartum, mums in the mixed feeding and exclusive formula feeding groups had higher mean PPWR than those in the group who exclusively breastfed (2.37 and 3.24 kg, respectively). These effects were sustained after adjusting for potential confounders (2.23 and 3.14 kg).

The adjusted models at 12 months postpartum still showed higher mean PPWR for mixed feeding and exclusive formula feeding as opposed to exclusive breastfeeding (1.92 and 2.79 kg, respectively).

Compared with exclusive breastfeeding, mixed feeding and exclusive formula feeding were tied to higher risks of developing substantial PPWR at 6 months (adjusted risk ratios [aRRs], 1.85 and 2.11, respectively) and remained so at 12 months (aRRs, 1.46 and 1.88, respectively).

According to the researchers, despite the lack of statistical significance, the more pronounced effect in the exclusive formula feeding group suggests that “any level of breastfeeding helps mitigate PPWR, with the most significant benefits arising from exclusive breastfeeding [particularly within an Asian context]”.

They attributed the effect in the formula feeding group to the lack of metabolic benefits that may be derived from breastfeeding. [Curr Opin Clin Nutr Metab Care 2019;22:413-417] “These include enhanced calorie expenditure and increased prolactin secretion, which facilitates mobilization of adipose tissue stores and inhibits lipogenesis.”

Higher BMI tied to greater benefit

On subgroup analyses, women with pre-pregnancy overweight or obesity (BMI ≥23 kg/m²) who practiced mixed or exclusive formula feeding had greater PPWR (RRs, 2.15 and 2.23, respectively) compared with their lean counterparts (<23 kg/m²; RRs, 1.22 and 1.82) at 12 months.

“[This is] an additional benefit for women with high BMI. Due to hormonal factors, there is a redistribution and management of their body fat to the extent that there is an opportunity for them to lose more than the postnatal weight gain,” noted lead study author Dr Loy See Ling from the Department of Reproductive Medicine, KKH, in the press release.

“[This] draws attention to targeted interventions to promote breastfeeding among women with overweight or obesity,” noted Loy and colleagues in the published paper. [Nutrients 2024;16;doi:10.3390/nu16132172]

Exclusive breastfeeding encouraged

Using data from the CRADLE* programme, this study evaluated the correlation between breastfeeding practices and PPWR at 6 and 12 months postpartum in 379 first-time mums (mean age at consent ~31 years). The mums either exclusively breastfed or formula-fed or practiced both. Overall, about a third of participants had substantial PPWR at both 6 and 12 months.

Asians are apparently more likely to accumulate abdominal or visceral fat than other populations. “[PPWR] can lead to concerns such as stress, anxiety, and depression, especially in Singapore’s culture where there is an emphasis on a rapid return to pre-pregnancy weight,” Loy pointed out.

“In women with multiple pregnancies, each instance of retained weight can accumulate, resulting in a significant long-term weight increase that can impact pregnancy outcomes and long-term health, thereby increasing the risk of obesity, diabetes, and heart diseases for both mother and child,” Loy continued.

The results underpin the critical need for national strategies aimed at improving postnatal care services. “[The findings are] of particular interest in Singapore where we are facing a rising obesity rate at 10.5 percent in a year,” said Loy.

“Encouraging exclusive breastfeeding alongside targeted lifestyle changes may serve as an effective intervention for enhancing the metabolic health of young mothers and their families after childbirth especially if they have high BMI, thus decreasing the likelihood of mother and child developing obesity, diabetes, and cardiovascular diseases in later years,” Loy added.