Reasons To Limit Oils If You Have Type 2 Diabetes

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Written by Lauren Ranley, MS, RD

At Reversing T2D, we encourage a diet rich in whole, plant-based foods and limited oil consumption. Most oils contribute a significant amount of calories but little nutritional value to the diet, as they are pure fats extracted from whole foods. Consuming a diet high in calories and high in fat can contribute to insulin resistance, the underlying cause of type 2 diabetes. Healthy fats, important for certain bodily functions, are best sourced by eating whole, plant-based foods rather than from consuming oils if you have type 2 diabetes. We’ll give you some suggestions to make cooking without oil easy!

 

Not All Fats Are Created Equal For Diabetes

Dietary fat is one of the three essential macronutrients, the others being protein and carbohydrates. The fat found in our food typically comes in two forms: saturated (often referred to as unhealthy fat) or unsaturated (more commonly known as healthy fat). The top sources of saturated fat in the American diet include cheese, beef, deli meats, fried foods, and some oils. Studies show that a diet rich in saturated fat can lead to inflammation, insulin resistance, and high cholesterol [1][2]. On the other hand, most unsaturated fats primarily come from plant-based foods such as avocado, nuts, seeds, and some oils. A diet that emphasizes unsaturated fat tends to reduce inflammation and improve cholesterol levels [3]. 

But how does oil play into this? Most oils, with the exception of coconut and palm oil, contain mainly unsaturated fat. However, it’s important to note that all oils are still highly calorie-dense foods. Let’s examine the profile of oils, how they are extracted from food, and how they play a role in type 2 diabetes.

 

Where Does Oil Come From?

The extraction process removes oil from the whole food, i.e., olive oil from the olive, creating a concentrated fat extract and removing most of the nutrients found in the food itself. RBD is an acronym that describes how oils are produced. It stands for Refined, Bleached, and Deodorized. This process can differ depending on the type of oil being extracted, but some components can look the same. For example, bleaching clay removes any coloring from the oils. Heat or steam is used to bring the oil to a high temperature to remove odors (deodorizing), and the last step usually involves filtering the oil, sometimes twice. Common RBD oils include [4]:

1. Canola oil
2. Soybean oil
3. Sunflower oil
4. Safflower oil
5. Grapeseed oil
6. Coconut oil
7. Refined olive oil
8. Pure olive oil

For the most part, extra-virgin and virgin olive oil do not undergo the RBD process. The olives are washed in cold water, mashed into a paste, and spun in a centrifuge that extracts the oil. For extra-virgin olive oil, this process takes place within 24 hours of harvest, but for virgin olive oil, it can take place outside the 24-hour window [4].

 

Nutrition Profile of Oils

Now that we have a general understanding of how oils are extracted from their whole food sources, let’s compare the nutritional value of the two. A ½ cup of olives contains 116 calories, 12g of fat, 3g of fiber, 1g of protein, and is a good source of iron, calcium, and vitamins A and E, while ½ cup of olive oil contains almost 1,000 calories, 100g of fat, and a few other nutrients. As you can see, ½ cup of olive oil contains significantly more fat and calories and is far less nutritious than 1/2 cup of olives.

Foods that contain a high amount of calories but little nutrients, like oils, are commonly referred to as energy-dense foods. A nutrient-dense food is rich in vitamins, minerals, complex carbohydrates, lean protein, and healthy fats relative to its calorie content. For example, a tablespoon of flaxseeds can be a great source of fat, and it also provides fiber, thiamine (vitamin B1), and copper.

 

How Oils Impact Type 2 Diabetes

Type 2 diabetes is a condition caused by insulin resistance. If you are unfamiliar with insulin resistance, then we encourage you to read this blog. To summarize, insulin resistance arises from fat accumulating in muscle and liver cells, causing an inflammatory response that disrupts the insulin pathway. Fat starts to accumulate in cells when we consume more dietary fat than we need. As we know, oils are very high in fat and calories, so limiting them can help reduce the number of calories in our diet. By choosing whole, plant-based foods and limiting oils, we can get the fat and nutrients our bodies need without disrupting the insulin pathway.

 Choosing The Right Fat For Type 2 Diabetes

Dietary fat plays several roles in our health. For starters, fat is an important component of cell membranes, specifically in the brain and nervous tissue. It is also essential for the absorption and storage of fat-soluble vitamins (vitamins A, D, E, and K) as well as for the production and proper functioning of certain hormones. To provide your body with the small amount of fat needed, consume nutrient-dense foods that contain unsaturated fats instead of calorie-dense oils.

Alternatives to Oil:

Instead of cooking with oils, consider these easy alternatives:

• Sauteing: use water or vegetable broth; add in 1-2 tbsp at a time and continue to toss the food to prevent burning 
• Baking: use mashed bananas, unsweetened applesauce, or a flax egg. These options will also add more nutrients and fiber to your baked goods! 
• Roasting and Steaming: can be done without oil. For flavor, add herbs and spices! Silicone baking mats are great for roasting because they eliminate the need for oil and make cleanup easy. 
• Sauces: puree beans with vegetables, then add water or almond milk to liquefy them.
• Dressings: blend whole nuts and seeds in a food processor for a creamy and nutrient-dense dressing.

 

References

[1] Riccardi et al. (2004). Dietary fat, insulin sensitivity and the metabolic syndrome. Clinical Nutrition.

[2] American Heart Association (2024). Saturated fats. AHA.

[3] Lunn & Theobald (2006). The health effects of dietary unsaturated fatty acids. Nutrition Bulletin.

[4] Broaddus H. (2017). What does RBD mean in relation to bulk oils? Centra Foods.