Roughly 1 out of every 4 adults worldwide may have insulin resistance — a metabolic problem that makes it harder for the body to use insulin and keep blood sugar in check. Over time, that can raise the risk of type 2 diabetes.
Sugar gets most of the blame. But researchers say another part of the diet deserves attention: the quality of the fat you eat.
A recent review from University of Barcelona researchers focused on two common fatty acids with very different effects: palmitic acid, a saturated fat found in palm oil, meat and dairy, and oleic acid, the monounsaturated fat abundant in olive oil. Their conclusion: when it comes to insulin resistance, the type of fat may matter more than the amount.
Two fatty acids with opposite effects on insulin resistance
Palmitic acid, found in palm oil, and oleic acid, abundant in olive oil, were both found to play a role in insulin sensitivity and type 2 diabetes risk, though their effects were quite different.
According to the researchers, palmitic acid promotes the accumulation of bioactive lipids, stokes low-grade chronic inflammation, and activates molecular pathways that impair insulin signaling.
These processes “are closely linked to impaired insulin action and the progression of metabolic disease,” the researchers say.
Why oleic acid may help protect insulin sensitivity
Then there’s oleic acid, which has a more favorable metabolic profile. It promotes the storage of lipids in more metabolically inert forms, which means they have minimal impact on physiological processes. And oleic acid helps preserve proper insulin signaling in key tissues such as the liver, muscle and adipose (fat) tissue.
This means oleic acid may counteract many of palmitic acid’s adverse effects, which could explain why diets like the Mediterranean diet are consistently linked with a lower risk of type 2 diabetes and other metabolic diseases.
“This review highlights the significant role of the quality of dietary fat, rather than the total amount consumed,” notes Professor Manuel Vázquez-Carrera of the University of Barcelona.
Future research should differentiate the effects of fatty acids by source, processing, and specific lipid species using randomized controlled intervention trials.
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Source is key
One important finding of the review was the metabolic impact of oleic acid may depend on whether its dietary source is from plants or animals. While there is no chemical difference between the oleic acids found in plants and animals, the animal sources also contain saturated fatty acids — including palmitic acid — found to raise metabolic risk.
Future studies should be more targeted so they can illuminate discrepancies observed in the epidemiological studies reviewed. “It is important to consider variables such as the source of fatty acids, their dietary context, interactions with other nutrients and different food processing methods,” Vázquez-Carrera says.
According to the researchers, a better understanding of these factors will allow a more accurate assessment of the impact of different types of fat on metabolic health. It also will help develop more effective nutritional strategies for preventing or managing type 2 diabetes.
Foods to limit for less palmitic acid
If you’re trying to reduce palmitic acid, focus first on the biggest and most common sources — especially palm oil, fried fast foods, processed baked goods, butter, high-fat dairy and fatty cuts of meat.
Suggested list:
Packaged foods made with palm oil or palm kernel oil, including some baked goods, cereals, microwave popcorn, nondairy creamers, margarine, candy, chocolate and ice cream
- Fried fast foods and restaurant foods cooked in palm oil or shortening
- Butter, full-fat cheese and whole milk
- Fatty and processed meats, especially red meat
- Cocoa butter and some chocolate products
- Coconut oil, used sparingly, since it is high in saturated fat even though it is not the top palmitic acid source
Plant-based sources of oleic acid
To get more oleic acid, favor plant-based, unsaturated fat sources such as:
- Extra-virgin olive oil
- Avocados and avocado oil
- Almonds, hazelnuts, macadamia nuts, pecans and peanuts
- Sunflower seeds and high-oleic sunflower oil
- Canola, sesame and soybean oils, used in place of butter or shortening
Sources:
Quality versus quantity of fat in the diet — Institut de Biomedicina de la Universitat de Barcelona
Palmitic and oleic acids in type 2 diabetes mellitus — Trends in Endocrinology & Metabolism
Global prevalence of insulin resistance in the adult population: a systematic review and meta-analysis — Frontiers in Endocrinology
Fat and Sugar: The Deadly Duo Behind Insulin Resistance — Observatoire de la Prevention
What is oleic acid and what are its properties? — La Almazara
Is Palmitic Acid Good or Bad for You and Which Foods Are High in It? — MedicineNet
Cholesterol Education: Palm Oil Redemption — Today’s Dietician
FAQ: Fat and Insulin Resistance
Not by itself, but certain saturated fatty acids — especially palmitic acid — have been linked with impaired insulin signaling and metabolic dysfunction.
Olive oil is rich in oleic acid, a monounsaturated fat that researchers say has a more favorable metabolic profile and may help preserve insulin signaling.
No. The review emphasizes fat quality over total fat quantity. Replacing some saturated fats with unsaturated fats from olive oil, nuts, seeds and avocados is a more balanced approach.
Palm oil, palm kernel oil, butter, high-fat dairy, fatty meats, cocoa butter, shortening and many packaged or fried foods can be major sources.
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