Insulin impacts each stage of Milk Production – Implications for Insulin Resistance

Best known for regulating blood glucose, the hormone insulin also plays a crucial role in milk production. During pregnancy, it helps prepare the mammary glands for lactation, supports the shift from colostrum to milk after birth, and works alongside other hormones to meet the nutritional needs of both mother and baby throughout nursing.

Pregnancy

During pregnancy, insulin works alongside hormones like estrogen, progesterone, and prolactin to prepare the specialized cells in the mammary gland for milk production. A 2021 study highlights insulin’s crucial role: while mammary tissue can form without insulin, it cannot produce milk.[1]

Postpartum

Insulin sensitivity is crucial for healthy lactation. It stabilizes blood glucose levels, ensuring there’s neither too much nor too little glucose in the bloodstream. Insulin also facilitates the uptake of glucose into mammary epithelial cells, providing the necessary building blocks for lactose synthesis. This steady supply of glucose allows lactose—the primary sugar in breastmilk—to be produced consistently within the luminal cells (the specialized cells lining the milk-producing ducts of the mammary glands). Along with hormones like prolactin and cortisol, insulin activates the enzymes responsible for lactose production.

Lactose plays a key part in milk production by drawing water and electrolytes into the milk, increasing its volume through a process known as ‘osmosis.’[2] As lactose accumulates in the secretory vesicles of mammary cells, it creates an osmotic gradient that pulls water into the vesicles, increasing milk volume and balancing its composition. Without sufficient lactose production, this osmotic balance would be disrupted, leading to reduced milk volume.

After childbirth, mammary gland cells become more sensitive to insulin, prompting the pancreas to produce more of the hormone. Around two weeks after childbirth, insulin levels decrease. At this juncture, mammary glandular tissue is so sensitive to insulin that it requires less to achieve the same effects. The increased sensitivity of the mammary gland cells is vital, as insulin supports the uptake of fatty acids and proteins, further enriching the milk to meet the infant’s nutritional needs. This intricate chain of events ensures that breastmilk is both nutrient-rich and sufficient in quantity to nourish the baby.

Insulin Resistance

Insulin resistance occurs when the body’s cells become less responsive to insulin. Given insulin’s roles in preparing the mammary gland during pregnancy, initiating milk production post-birth, and maintaining milk supply, it’s understandable why those mothers who have insulin resistance may face challenges in building and maintaining their milk supply.

Whole-Body Complications

Insulin resistance is often accompanied by low-level systemic inflammation, suboptimal hydration, and elevated estrogen levels—all of which can interfere with milk production. Elevated estrogen, in particular, can shorten the duration of lactational amenorrhea—the natural pause in ovulation and menstruation that occurs while nursing. With the return of the menstrual cycle, milk production often becomes more challenging for many mothers, sometimes requiring supplementation of calcium and magnesium, as well as the use of specialized herbs, to maintain lactation.

Observation confirms that mothers with insulin resistance often need to eat more calories or even gain weight to sustain their milk supply. This is likely because their body’s delayed and compromised response to insulin makes it harder to efficiently regulate the energy required for milk production.

Additionally, the stress mothers experience while navigating milk supply challenges can raise cortisol levels, which may further disrupt milk production.

How the Lactogenic Diet and Lifestyle can Help

The Lactogenic Diet offers a holistic approach. It utilizes dietary and lifestyle strategies that increase insulin sensitivity, reduce inflammation, improve hydration, improve the gut biome, and reduce and manage stress. We call these actions the Five Pillars of a Lactogenic Diet and Lifestyle.

Who has Insulin Resistance?

In today’s world, nearly everyone who has not taken deliberate steps to prevent insulin resistance likely has some degree of it. Insulin resistance is commonly found in individuals who easily gain weight, are overweight or obese, or have hormonal imbalances such as Polycystic Ovarian Syndrome (PCOS) or Metabolic Syndrome. It is also present in women at risk for gestational diabetes, as well as those diagnosed with pre-diabetes or type II diabetes. According to a recent survey, 10% of women in the United States are at risk for gestational diabetes. [3]

Globally, rates of obesity and diabetes have been steadily rising since the early 1970s. By 2030, it is projected that 30–50% of the world’s population will have pre-diabetes or type II diabetes.[4]

Clearly, in our present time—and even more so in the future—pregnant and breastfeeding mothers will face the challenges of insulin resistance. These mothers will require additional support and guidance to protect their health and ensure successful lactation. 

What lies ahead for Breastfeeding Mothers?

For mothers who plan to nurse their babies, the worldwide increase in insulin resistance means that specialized interventions are needed to support their best efforts. 

My own low milk supply was linked to Insulin Resistance, Polycystic Ovarian Syndrome, and Insufficient Glandular Tissue (IGT). I overcame my imbalances and produced a full supply after researching and utilizing the Lactogenic Diet. Presently, the best overview of the Lactogenic Diet is found in my book Mother Food. 

Expert Guidance

Many lactation specialists have a good understanding of insulin resistance and its complications. They can help you, together with your healthcare provider, to develop an effective combination of herbal galactagogues, dietary adjustments, medications (if needed), and exercise; often, this combination quickly improves insulin sensitivity and helps to improve your milk supply. It is actually amazing how quickly the body responds to changes in diet and lifestyle, and shows measurable improvements.

To begin, mothers can include lactogenic ingredients in meals, snacks and beverages (see my Lactogenic Foods and Herbs Handouts). These ingredients are considered safe.

Always talk to your doctor about changes in diet or the use of supplements, especially if you are taking medication. In particular, lactogenic ingredients can have interactions with blood-thinning or blood-sugar lowering medications.

Hi! I'm Hilary Jacobson, and I've been helping moms with milk supply issues for over 30 years. My book, 'Mother Food,' was a game-changer when it first came out, and I'm still at it—researching, writing, and teaching to make sure new moms get the support they need. Want to stay in the loop? Sign up to my newsletter for updates. 

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[1]Watt, A. P., Lefevre, C., Wong, C. S., Nicholas, K. R., & Sharp, J. A. (2021). Insulin regulates human mammosphere development and function. Cell and Tissue Research, 384, 333-352.

[2]Sadovnikova, A., Garcia, S. C., & Hovey, R. C. (2021). A comparative review of the cell biology, biochemistry, and genetics of lactose synthesis. Journal of Mammary Gland Biology and Neoplasia, 26(2), 181-196.

[3]Lende M, Rijhsinghani A. Gestational Diabetes: Overview with Emphasis on Medical Management. International Journal of Environmental Research and Public Health. 2020; 17(24):9573. https://doi.org/10.3390/ijerph17249573

[4]Ampofo, A. G., & Boateng, E. B. (2020). Beyond 2020: Modelling obesity and diabetes prevalence. Diabetes Research and Clinical Practice, 167, 108362.