Low carb / High Fat Eating, Keto, Fasting & Lactation

April 22, 2020 Shondra Mattos

Let's talk LCHF eating, fasting & lactation.

This question was asked in a breastfeeding group and I wanted to share my answer then expound on it. I figure what better do we have going on during #quarantine2020 than learn a bit of science. lol.

The question:

Is it safe to do keto diet and breastfeed?

My response: Strict Keto during lactation has been linked to Lactation Ketoacidosis, which while is unlikely to happen if calories are maintained and carbs aren't reduced to a crazy amount, it is possibly underreported (per the studies). I would say get familiar with the symptoms of ketoacidosis, don't severely limit your carbs, maintain sufficient calorie intake (500 calories on top of normal metabolic needs is needed to maintain lactation) and don't do extended fasting periods. The metabolic changes that occur during pregnancy and lactation make it so that one is more likely to have elevated ketone production due to how milk is made making it something that needs to be monitored closely if you chose to do it. :)

The science:

We know that Low Carb/High Fat diets such as keto are well tolerated and beneficial for most non-lactating, non-pregnant folks. The safety of that type of eating is less known during lactation due to the changes in one's metabolic state during that period.
During lactation, many of our cells work differently. Some work harder, some less so, and the demands put on them differ dramatically than when not lactating. Making milk is an energy-intense process and requires 500 ADDITIONAL calories, on top of what's normally needed, to keep the lactating parent's energy balance equal.
When calories expended is greater than intake, cells will switch how and from where they get their energy. This is also true when the source of energy changes, and is the premise of the keto diet- stop using carbs for energy and instead rely on fat for energy.
The primary source of energy our body uses for energy is glucose. The primary source of glycogen is carbohydrates. glycogen is stored in the liver and when needed for energy is broken down into glucose. When carbs are low in quantity, the body will first use the stored glycogen but then the body switches to creating glucose from non-carb sources (Gluconeogenesis), and this is required to sustain lactation as glucose is ABSOLUTELY needed for milk synthesis
Additionally, changes to the way our bodies synthesize insulin occur in lactation.
This all can take place when carbs are restricted, even when calories are met, or when fasting occurs for greater than 42 hours.

So to recap: During lactation, we have an increased energy demand, we need glucose for milk making, and when carb intake is low either because of carb restriction or fasting, we rely on our liver stores of glycogen to form glucose. When that is depleted, our bodies start using non-carb sources (aka fat) for energy.

The problem:

The byproduct of fat breakdown (lipolysis) increases the circulating fatty acids, which are then taken up in the liver and converted to ketone bodies. This is the reason why you can do urine tests to check if you're in ketosis. In a normal non-lactating state, increased ketones in the blood signals insulin release. However, because of the metabolic changes to insulin synthesis and how they respond to their receptors, the appropriate increase may not occur. As a result, ketone bodies continue to increase in the blood and may eventually cause Ketoacidosis: Keto (referring to ketones) Acid (pertaining to acid) Osis (denoting a pathological/abnormal state).

Excessive ketones in the blood is NOT good and Ketoacidosis is a life-threatening condition.

The good news:

Lactation Ketoacidosis is rarely reported, though it's suspected that it's underreported as mild cases may be missed due to a lack of seeking medical care or symptoms improve as intake increases.

Treatment involves providing glucose in an iv and increasing carb intake. Some providers may suggest a temporary stop to breastfeeding, though it's been treated successfully many times with adjustments to expression frequency with no need to cease breastfeeding.

Lactation Ketoacidosis is usually diet-related - a provider places a lactating parent on "nothing by mouth" due to pending surgery or acute illness, parents fast in hopes of losing postpartum weight, a lactating parent does a version of Low carb High fat (Banting, Keto, and even paleo have been reported as linked to Lactation Ketoacidosis) with or without meeting daily macro needs, etc- but it also has been reported with overproduction with a normal diet.

This underscores the importance of both meeting your specific calorie needs and maintaining an adequate carb intake because it's super important for staying healthy while lactating.

I didn't write this post to discourage LCHF eating, but rather provide more information to help parents decide if, when, and how they will incorporate the way of eating into their lifestyle. Strict Keto- such as under 20 g of carbs a day- is not appropriate for lactating parents by nature of biology. What number of carbs needed to avoid things such as Ketoacidosis remains unknown.

Symptoms of Ketoacidosis

Symptoms may include:

excessive thirst
More frequent urination
Shortness of breath and/or increased respiratory rate
Increased heart rate
nausea and/or vomiting
stomach pain
Fatigue
breath that smells fruity
feelings of confusion

Get familiar with the symptoms of Ketoacidosis so that you know when to seek medical help if they arise, meet with a lactation savvy nutritionist, and make appropriate adjustments to your eating knowing that your body is working in a whole different way than when you're not lactating.