How physically active mothers who breastfeed may protect their babies against obesity and diabetes

A researcher describes the important role for a baby’s health of a hormone found in the breast milk of mothers who took part in high intensity interval training
Two Hong Kong mothers who exercised after giving birth and breastfed their babies talk about the physical and mental benefits

Wellness

Lily Canter

Published: 4:15am, 1 May 2024

Why you can trust SCMP

Breastfeeding mothers have long been given unproven excuses not to exercise, among them the suggestion it could reduce their milk supply or make the milk turn sour.

There has been little scientific research on how exercise affects breast milk or its production, however.

To debunk myths with clinical evidence, researcher Trine Moholdt of the Norwegian University of Science and Technology did a study to learn more about breast milk from mums who exercised.

And the results, published in Frontiers in Nutrition in December, were fascinating.

Trine Moholdt of the Norwegian University of Science and Technology says women who did high intensity interval training (HIIT) had higher levels of the hormone adiponectin in their breast milk after exercise. Photo: Trine Moholdt

Mothers who took part in high intensity interval training (HIIT) had higher levels of the hormone adiponectin in their breast milk after exercise. This hormone is particularly important for regulating glucose levels and fat metabolism.

“The hormone is secreted from fatty tissue and enters the bloodstream, and much of what is in the blood goes into the milk. We were not that surprised by the findings, but now we know for certain,” said Moholdt.

This hormone is probably absorbed through the intestines of breastfeeding babies, changing how their metabolism functions.

An increase in adiponectin concentrations in breast milk may play a role in protecting against early rapid weight gain in infancy. Having low levels of this hormone is linked to insulin resistance and type 2 diabetes.

“Our findings indicate that maternal exercise during lactation can be one of the factors that affect the risk of childhood obesity. If breast milk adiponectin can protect against rapid weight gain in infancy, our results indicate that the best time to breastfeed is around one hour after high-intensity exercise,” the researchers said.

Find out why so many women in China choose not to breastfeed

Twenty new mothers took part in the research, donating a total of 240 samples of breast milk.

One hour after HIIT training, women who breastfed exclusively had a 22 per cent increase in adiponectin compared to a day with no exercise. The HIIT session consisted of a 10-minute warm-up at moderate intensity followed by four four-minute bouts at 95 per cent heart rate maximum, separated by three minutes of low to moderate intensity.

Moderate exercise of walking or jogging for 48 minutes at 70 per cent heart rate max did not have the same effect on adiponectin levels.

In 2020, the World Health Organization estimated that 39 million children under the age of five were overweight or obese. They also found that the incidence of overweight and obesity among children and adolescents aged five to 19 had risen from four per cent in 1975 to 18 per cent in 2018.

Breast-fed children are less likely to be overweight or obese than babies fed on formula, the World Health Organization says. Photo: Shutterstock

Research shows that one possible contributory factor in the rapid rise in obesity in children is that nutrition during the early phase of life partially determines health later in life.

“The period from conception to two years of age is considered the most critical period for possible development of obesity later in life. The primary aim of our research is to find out if we can limit the development of overweight in children,” said Moholdt.

One reason the WHO recommends breastfeeding during the first six months of life is that breast-fed children are less likely to be overweight or obese than formula-fed children.

New research shows that the composition of breast milk varies between mothers who have high and low body mass indexes, however, and differences in breast milk composition can play a role in whether a child develops obesity.

“We now have the first result of all the work we are doing, and many more results are on the way. It will be very exciting,” said Moholdt.

Elizabeth Montoyo breastfed her son Emilio until his second birthday. She ran a half marathon at about the same time. Photo: Elizabeth Montoyo

Active breastfeeding mothers describe exercise benefits

For Hong Kong-based breastfeeding mothers Elizabeth Montoya and Esther Bland, exercising has played an important part in their physical and mental well-being after giving birth.

Pre- and postnatal trainer Bland, from Aqua Terra Performance, began with walking and gentle Pilates before introducing weights and running to her routine three months after giving birth.

Her daughter, now nine months old, is still breastfed. Bland walks daily and exercises up to 50 minutes per session, three to six times a week.

“Sometimes she’s so hungry I don’t get the chance to shower after a workout, but she doesn’t seem to mind,” said Bland, who lives in Stanley on the south side of Hong Kong Island, where she runs her fitness studio.

Esther Bland, a pre- and postnatal fitness trainer, did not see a drop in her breast milk production after difficult workouts. Photo: Aqua Terra Performance

Despite believing that exercise is a stressor that can affect milk supply, Bland said she never noticed a drop in production after tough workouts.

“Personally, it’s a lack of sleep that has a bigger impact on my supply. So I take each day as it comes. If I’ve had a sleepless night, I modify my workout if needed,” she said.

Primary-school teacher Montoya, who exercises at least twice a week for up to 90 minutes, breastfed her son Emilio until his second birthday, two months ago.

“I started [yoga] with an aerial hammock after I got the OK at about 12 weeks post-partum,” says Montoya, who lives in Wan Chai. She then returned to dance exercises, using silk hammocks and a pole that require a bit more strength, and to running and playing soccer, starting slowly with jogs.

Take a swing at aerial yoga and you’ll soon forget all your cares

Around her son’s second birthday she ran a half marathon.

“I don’t know that he noticed any difference in the milk [after she returned to exercising], but I can say that I felt better. I was more patient and just happier and calmer. I did have post-partum anxiety, and even if it was difficult to get out and exercise, it helped my overall mood and mental well-being.”

Montoya would definitely recommend exercising while breastfeeding.

“It is so hard to make the time or get the energy, but once I did, I felt so much happier, and was just a better mom for my son.”

Like what you read? Follow SCMP Lifestyle on Facebook, Twitter and Instagram. You can also sign up for our eNewsletter here.

Post