Intermittent Fasting While Breastfeeding: Is it Safe?

I totally get why people try intermittent fasting while breastfeeding. Breastfeeding makes you want to eat a lot right at the same time you’re trying to lose weight. For some mums, like my friend Julia, eating like a teenage boy during footy season isn’t much of a concern because breastfeeding burns extra calories and helps them lose weight easily. At first. But, once your baby starts eating solids and you start breastfeeding less, those extra kilojoules begin to pile on. 


“Because I’m not nursing as much, I’m sure I’m gaining weight,” Julia confided. “That’s why I stopped eating breakfast and started occasionally skipping meals.”

Here’s the thing: Intermittent fasting is the latest health craze, but what’s it all about? And more importantly, is intermittent fasting while breastfeeding okay to do?! We spoke to Freda Rosenfeld, a board certified lactation consultant in New York City, and got the skinny on when intermittent fasting is okay to do (and when it’s not).

What is intermittent fasting, and why is it done? 

As the dictionary defines it, fasting is abstaining from food or drink, and intermittent fasting basically means you skip certain meals within the day, or don’t eat for specific intervals within the day or week. Popular variations include Leangains and 5:2. Further research is needed, but some experts believe that kilojoule restriction and fasting can lead to a longer life and reduced risk of certain diseases, as well as weight loss.

In general, is it safe to fast?

“There seem to be benefits when fasting is done appropriately,” says Rosenfeld. “If you’re diabetic you can’t fast, but studies show that fasting in healthy adults can protect sugar levels and perhaps help keep you from becoming diabetic later in life.” Fasting can also help reduce inflammation, and the risk of cancer, diabetes and heart disease. 

Is intermittent fasting while breastfeeding okay?

“I would urge against it,” says Rosenfeld. Although it might be a good way to jumpstart a diet once breastfeeding is over, the most important thing while feeding your baby is your caloric and hydration needs. “Mums need 500 calories more than average when they’re nursing, so if they’re fasting it can have ramifications,” she adds.

Breastfeeding mums need to know that intermittent fasting can cause exhaustion and severe dehydration which in turn will lead to less milk production. “Chances are mum will have enough milk for the baby the day that she’s fasting, but the next day there’s a potential for less milk.” Something else to keep in mind: In addition to decreasing your milk supply, Rosenfeld adds that dehydration can also lead to clogged ducts from dried-up breastmilk.

How will intermittent fasting while breastfeeding affect baby?

“I’m more worried about the mother than the baby,” says Rosenfeld. For starters, fasting decreases your energy. “When the mother is exhausted, it’s harder for her to take care of her baby.” If the mother is truly fasting only intermittently, then her milk supply may go back up when she’s eating properly again. However, that also depends on your baseline milk supply.

What if a mum needs to fast for religious reasons?

There are also plenty of mums who fast intermittently while breastfeeding for religious reasons, such as Yom Kippur or Ramadan, and Rosenfeld says that it is not uncommon for their breastmilk supply to dip while they’re fasting.

If you need to fast for religious reasons, her advice is to eat more the days before the fast (especially protein) and stay very well hydrated to help your milk supply return to normal after the fast is over. 

How can breastfeeding mums lose weight safely?

A lot of it comes down to diet and exercise. “If you eat what a healthy normal adult would eat you should lose weight, because your body has the extra calories burned from nursing,” says Rosenfeld. Check out our breastfeeding nutrition guide for more ideas.

Intermittent fasting may sound like a good idea — and maybe it is! — but save it for when your breastfeeding days are done. As for now, focus on a healthy diet and exercise plan, ensuring the health and safety of you and your baby.

More for breastfeeding mums:

Image: Getty