It’s long been hailed as a “healthy fat,” but new research shows that too much oleic acid — the main fat in olive oil — may quietly be fueling the obesity crisis.
Key Points at a Glance
- Oleic acid, abundant in olive oil, promotes the creation of new fat cells
- It increases the fat-storage capacity by stimulating precursor cell proliferation
- Other common dietary fats did not trigger the same effect
- Excess oleic acid may contribute to obesity and related diseases
- Moderation and fat variety are key to healthier outcomes
Olive oil has long enjoyed its reputation as a health food darling — praised by Mediterranean diets, doctors, and wellness influencers alike. But a new study published in Cell Reports challenges that image by revealing how high levels of oleic acid, the predominant fat in olive oil, may actually trigger the body to make more fat cells.
Researchers at the University of Oklahoma College of Medicine, in collaboration with Yale and NYU scientists, tested how different dietary fats influence fat cell development. Among the fats found in coconut oil, milk, lard, soybean oil, and peanut oil, only oleic acid significantly increased the proliferation of precursor cells that develop into fat cells — a process known as adipogenesis.
“Think of fat cells as an army,” said lead researcher Dr. Michael Rudolph. “Oleic acid increases the number of soldiers, or fat cells, ready to store excess nutrients. That bigger army means more storage potential — and if we keep feeding it, obesity follows.”
Mechanistically, oleic acid acts by boosting the signaling protein AKT2 and dialing down another called LXR, both of which regulate fat cell growth. Over time, this metabolic tweak can build up the body’s capacity to store fat, leading to weight gain, inflammation, and ultimately raising the risk of conditions like heart disease and type 2 diabetes.
Importantly, the study didn’t indict olive oil itself, but rather its excessive consumption. The researchers noted that modern diets — especially in fast food-heavy environments — contain increasingly high levels of oleic acid, often due to the replacement of saturated fats with monounsaturated fats in processed foods marketed as “heart healthy.”
In humans, it’s difficult to isolate single fatty acids, as meals often include complex blends of fats. But with oleic acid so dominant in certain oils and processed foods, the cumulative exposure over time may nudge the body toward an obesogenic state.
“Balanced intake is key,” Rudolph emphasized. “Fats aren’t inherently bad, but too much of a good thing can backfire. A variety of fat sources appears to be healthier than loading up on just one type — even if it’s one with a good reputation.”
This research doesn’t overturn the value of olive oil in moderation — it adds nuance. For those already at risk of heart disease or obesity, it may be wise to rethink fat sources and lean into dietary diversity.
Source: University of Oklahoma Health Sciences Center
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