A new study published in Cell Reports suggests that a high-fat diet rich in oleic acid—a major fatty acid found in olive oil—may increase the risk of obesity by causing the body to produce more fat cells.
The research, led by scientists from the University of Oklahoma and Yale University, points to oleic acid’s specific role in fat cell development, especially when consumed in high amounts over time.
Oleic acid is a monounsaturated fat often praised for its heart-healthy properties and found in foods like olive oil, avocados, and some nuts. However, this new study shows that the way the body responds to different fats may be more complex than previously thought.
Rather than all dietary fats having the same effects on the body, certain fats like oleic acid may influence how fat cells are formed and stored.
Dr. Michael Rudolph, the study’s lead author and an assistant professor at the University of Oklahoma College of Medicine, said the research team wanted to understand whether obesity results from simply eating too much fat or if certain types of fat play a more direct role in the process.
To explore this, they fed mice different diets enriched with specific fatty acids commonly found in various oils and animal products—such as those in coconut oil, lard, milk, peanut oil, and soybean oil.
Among all the fats tested, only oleic acid was found to stimulate a notable increase in the number of precursor fat cells—also known as pre-adipocytes—that later develop into full fat cells. This happened through changes in cell signaling.
Oleic acid activated a protein called AKT2 that encourages cell growth and at the same time lowered activity in another protein called LXR, which normally helps regulate fat cell formation. This combination caused fat-forming cells to grow more rapidly.
Dr. Rudolph used a simple analogy to explain the process: “You can think of fat cells like an army. When you consume oleic acid, you’re recruiting more soldiers into the army. That gives your body more capacity to store extra calories.
Eventually, if you keep eating more than your body can use, you can end up with obesity, and that can lead to serious health problems like heart disease or diabetes.”
While the study was done in mice, it raises important questions for human diets. Most people don’t eat just one type of fat—they consume a blend of many fats across different meals and foods. Still, the study highlights how the modern diet, which includes higher levels of oleic acid especially in processed and fast foods, might play a role in the growing obesity epidemic.
Dr. Rudolph pointed out that oleic acid isn’t harmful on its own and may even be beneficial in moderate amounts. In fact, many studies have linked olive oil to improved heart health, especially when it replaces saturated fats in the diet. But this new research shows that problems may arise when oleic acid is consumed in very high quantities and over long periods of time.
“The takeaway here is to eat fats in moderation and get them from a variety of sources,” Dr. Rudolph said. “It’s not about cutting out olive oil or nuts—these foods can be part of a healthy diet. But relying too heavily on one type of fat, even a ‘healthy’ one like oleic acid, might not be wise—especially for people at risk of obesity or heart disease.”
In short, while olive oil and similar foods may still offer health benefits, this study serves as a reminder that too much of even a good thing can tip the balance in the wrong direction. A balanced and varied diet remains the key to long-term health.
If you care about weight loss, please read studies that hop extract could reduce belly fat in overweight people, and early time-restricted eating could help lose weight .
For more health information, please see recent studies that Mediterranean diet can reduce belly fat much better, and Keto diet could help control body weight and blood sugar in diabetes.
The research findings can be found in Cell Reports.
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