Over the years I have had many mothers ask me if low carb diets are safe while breastfeeding and recently several mothers have asked me if the keto diet is compatible. Many people find that a low carb or keto diet helps them to lose weight rapidly without being hungry all the time or experiencing cravings, and of course after having a baby, many women are looking for some kind of diet plan. A few weeks ago the IABLE came out with a parent handout about the keto diet in relation to breastfeeding, as well as making it the subject of their weekly #LACTFACT question.

They discuss a risk of low carb and keto diets called ketoacidosis. This can occur when the body is burning fat and produces an excess of blood ketones which causes the blood to become too acidic. This rare but life threatening illness is more likely to occur during breastfeeding because of the extra calories the body requires to make milk. This condition is fairly common among dairy cows during early lactation because the energy required to make large quantities of milk is often much more than the cow is physically able to eat. Cows suffering from this condition have to be given large quantities of intravenous glucose and steroids to save their lives.
In addition to the low but real risk of ketoacidosis (Google: lactating women ketoacidosis), a woman who starts on a low carb or keto diet is often restricting her daily calorie intake very rapidly and this can result in a decrease in milk production. Experts who study “blue zones” – areas of the world where populations live longer and are generally very healthy – have found that the typical diets in these areas consist of legumes, grains and vegetables and generally relatively low amounts of dairy, meat, and fat. Long term, these “blue zone” diets are probably more sustainable and balanced than low carb dieting.
The authors of the keto diet and breastfeeding handout recommend that women considering a low carb or keto diet while breastfeeding use caution. They suggest consultation with a dietician or physician before strictly eliminating carbohydrates or dramatically reducing calories. A diet with increased protein and fewer carbohydrates may be helpful for lessening hunger and cravings while losing weight, but completely eliminating carbohydrates while breastfeeding is probably not wise, particularly during exclusive breastfeeding.