Does Dairy Decrease Insulin Sensitivity?

When you think about the negative effects that dairy has on the body, what comes to mind? 

My guess is probably digestive upset and lactose intolerance. Maybe you consider inflammation and dairy’s propensity to cause acne. 

Insulin sensitivity may not have come to mind. However, it is important that we consider this.

On the flip side of the coin, when you think about foods that impact blood sugar and insulin sensitivity, what comes to mind? 

Usually, we think of candies, chocolate, pastries, and other sweets. But what about dairy? 

It is possible dairy does play a role in all this. Let’s discuss dairy and insulin.

What is dairy?

Dairy is any food product that is made from an animal that lactates. Some of these include: cow’s milk, sheep’s milk, and goat’s milk. 

Dairy products include the following foods:

  • Milk: Dairy milk is the base for all other dairy foods. There are several forms of milk, such as skim milk (which is a low fat dairy).

  • Cream: Cream is made by skimming the top layer of milk. This layer is full of fat.

  • Butter: You can get butter by taking cream and separating butterfat from buttermilk.

  • Cheese: Cheese is a coagulation of casein, one of the proteins in milk.

  • Yogurt: Yogurt is made through the fermentation process of converting milk sugar into lactic acid from either milk or cream.

Dairy contains protein, fat, carbohydrate, and other nutrients. Dairy intake tends to be high in ketogenic diets due to its fat content. This can help to achieve ketosis. 

These nutrients include calcium, phosphorus, and potassium. The main carb in dairy is lactose. This is a milk sugar that our bodies break down using the digestive enzyme lactase.

Human lactase production is high when we are infants. However, this declines as we age. Up to 75 percent of the adult population is lactose intolerant.

Dairy also contains proteins. The primary dairy proteins are casein and whey. Whey is digested fairly quickly. Casein is digested slowly. This is how it provides a steady release of amino acids into our blood.

What is insulin sensitivity and why is it important?

Insulin is an important hormone that helps us to control the level of glucose in our blood. Insulin sensitivity and the insulin index show how sensitive our body’s cells are in response to insulin.

High insulin sensitivity lets our body’s cells use blood glucose more effectively. This maintains lower blood sugar levels. 

Low insulin sensitivity, on the other hand, is what we call insulin resistance. Our cells do not absorb as much glucose. This can lead to high blood sugar levels. If this isn’t managed, it can progress to type 2 diabetes.

Insulin sensitivity varies from person to person. It can change according to different lifestyle and nutrition factors. Improving insulin sensitivity is important because it may benefit people who have or are at risk of developing type 2 diabetes.

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Does dairy decrease insulin sensitivity?

The answer to this question is still up for debate. However, here is what we know on the topic.

Milk contains natural sugars. It also contains fatty acids and proteins. Usually, fats and proteins help glucose to enter the blood more slowly and steadily. However, dairy is what we call an insulin secretagogue.

This means that dairy prompts the pancreas to release insulin. But this happens to a higher degree than we would expect for its glycemic index. In fact, in people with type 2 diabetes, the insulin spike is five times greater than what you might expect.

The extra insulin levels that are released after eating dairy aren’t always a good thing, though. Even though blood glucose levels are lower when we eat dairy, we can become more insulin resistant the next day. Even though the fat in milk can help regulate blood sugar in the short term, all that sugar still needs to be metabolized.

Dairy triggers disproportionately higher levels of insulin release, given its carb content. In fact, the amount of insulin the pancreas releases in response to dairy is between three to six times more than what you would expect.

When people consume pure lactose, the insulin response matches lactose’s glycemic index. This means that there is something else about dairy that increases insulin secretion.

So why is dairy insulinogenic? The exact reason is still unknown. Researchers believe that the proteins in milk play a role in all this. The whey protein in milk increases insulin by up to 90 percent! There are also amino acids that the pancreas releases after incretin hormones, which may play a role.

What the studies say

One study looked at 272 middle-aged women without diabetes. They found a significant correlation between dairy intake and higher insulin resistance.

Another study looked at the impact of dairy on blood sugar relations in patients with metabolic syndrome. This is a collection of symptoms, including insulin resistance. They split the study subjects into three groups: limited dairy, low-fat dairy, and full-fat dairy. 

After three months, there was no difference in any of the groups’ blood sugar levels. However, participants in both the low fat and full-fat dairy groups were insulin sensitive.

A different study looked at eight year old boys. These boys ate 53 grams of protein every day. Their protein intake was either meat or milk. 

After just one week, the fasting insulin concentrations in the milk groups doubled. They also developed insulin resistance. Participants in the meat-eating group had no increase in insulin or any insulin resistance.

A 2014 review looked at ten short and long-term intervention studies. For subjects of a healthy weight, higher dairy consumption didn’t affect their glucose tolerance. For those who were overweight and obese, the impact of dairy is mixed. 

Researchers believe that the effect of dairy may be less important than weight loss or exercise to decrease waist circumference and adipose tissue to improve risk factors.

This shows that dairy’s effects on insulin sensitivity depend on how healthy study participants are. Researchers in this study suggest there are conflicting results when studying insulin sensitivity. This is because there are so many factors that influence insulin sensitivity. Those factors can even interact with each other.

This means that changing one factor in insulin sensitivity could affect several others. For example, taking dairy out of your diet can impact insulin sensitivity. However, it can also affect body weight. Bodyweight directly impacts glucose metabolism.

5 other ways dairy can negatively affect your health

Heart disease

Dairy has been linked to a higher risk of developing heart disease and high blood pressure. This may be due to their content of saturated fats.


Dairy stimulates the release of insulin and a protein called IGF-1. These two substances are linked with increased acne.


High levels of insulin and IGF-1 are also associated with an increased risk of certain cancers. One of these is prostate cancer. Dairy has been associated with up to a 34 percent increased risk of prostate cancer.

Autoimmune conditions

Dairy intake is associated with a higher risk of autoimmune conditions, including multiple sclerosis and type 1 diabetes. Your immune system is supposed to protect you from foreign microbes and other harmful substances.

If your immune system loses its ability to recognize harmful substances and differentiate between them and healthy cells, it can attack your own body. Exposure to foreign peptides can trigger these self attacks. 

One example of a foreign peptide is the animal protein fragments that are present in dairy products. This is because these protein fragments have similar components to humans. Our body can get confused and identify our body’s own tissues as foreign. This causes the immune system to attack your own body.

Bone health

Consumption of dairy products is significantly linked to a higher risk of bone fracture. Dairy is high in calcium. This can cause vitamin D dysregulation. 

Vitamin D dysregulation can disrupt bone homeostasis. Also, consuming high amounts of animal protein can induce acidosis. The body then compensates by leaching calcium out of the bones. This is to neutralize the high level of acidity. Over time, this can have a negative effect on bone health.


Dairy is a bit of a tricky subject. There is a lot of debate around it. Is dairy good for you? Bad for you? Should you eat it or not? 

There is research to show that dairy can decrease insulin sensitivity. And remember, we want to have high insulin sensitivity so that our bodies can process sugar effectively.

If you have diabetes, it may be a good idea to avoid dairy. Speak to your health care provider about insulin sensitivity and any nutritional changes before making them.

Explore More


Find out the Top 8 Natural Ways to Boost Insulin Sensitivity.


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  7. Schmidt, KA; Cromer, G; Burhans, MS; Kuzma, JN; Hagman, DK; Fernando, I; Murray, M; Utzschneider, KM; Holte, S & Kraft, J. (2021). The impact of diets rich in low-fat or full-fat dairy on glucose tolerance and its determinants: a randomized controlled trial. The American Journal of Clinical Nutrition. 113 (3), 534-47.
  8. Sun, Q; Ma, J; Campos, H & Hu, FB. (2007). Plasma and erythrocyte biomarkers of dairy fat intake and risk of ischemic heart disease. Am J Clin Nutr. 86 (4), 929-37.
  9. Tucker, LA; Erickson, A; LeCheminant, JD & Bailey, BW. (2015). Dairy consumption and insulin resistance: The role of body fat, physical activity, and energy intake. J Diabetes Res. 1 (1), 1.
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