Healthy or Harmful? The Double Life of Oleic Acid in Olive Oil

We’ve long been told that olive oil is one of the healthiest fats you can eat. But new findings published in Cell Reports are challenging this golden reputation, at least when consumed in excess. Scientists have discovered that oleic acid, the main monounsaturated fat in olive oil, may actually stimulate the growth of new fat cells under certain conditions.

Not All “Good Fats” Act the Same

Oleic acid has earned its status as a “healthy fat” thanks to its well-documented benefits. Replacing saturated fats with oleic acid has been associated with lower cholesterol, reduced inflammation, and a lower risk of heart disease. It’s also known to play a role in weight management and protecting against certain chronic illnesses.

But researchers now say there’s more to the story. Their latest study suggests that while oleic acid can be good for you in moderation, too much of it may actually promote fat cell formation, potentially contributing to obesity and metabolic diseases.

How Oleic Acid Influences Fat Cell Growth

To dig deeper into how different fats affect our bodies, researchers fed mice specially designed diets high in various fatty acids, including those from sources like milk, lard, peanut oil, and coconut oil. Oleic acid stood out. Unlike the other fats, it triggered a significant increase in precursor cells, the early-stage cells that eventually become fat cells.

The mechanism behind this? Oleic acid was shown to activate the AKT2 protein (a key player in promoting fat cell growth) and suppress LXR proteins (which help regulate lipid metabolism and prevent excess fat buildup). This dual action essentially speeds up the creation of new fat cells.⁽¹⁾

Why this matters

Of course, most people don’t eat isolated fatty acids. Our meals are complex: toast with avocado and eggs, a tuna salad with almonds, creamy coffee, or pasta with meat sauce. All of these contain varying types of fats, making it difficult to track how much oleic acid we actually consume.

But here’s the issue: oleic acid levels are increasing in the global food supply, partly due to the rise of processed and fast food options that often rely on high oleic oils for shelf stability and cost-effectiveness. So while you're not drinking olive oil straight from the bottle, you may still be getting more oleic acid than you think.

This doesn’t contradict decades of research showing olive oil’s heart benefits—it simply underscores the importance of dosage and diet diversity in nutrition science.⁽²⁾

Olive Oil Isn’t the Enemy: Just Don’t Overdo It

This research doesn’t mean you need to toss out your bottle of extra virgin olive oil. In a world where we love labeling foods as "superfoods" or "villains," this study serves as a reminder: even the healthiest ingredients can have drawbacks when consumed in excess. Olive oil is still a smart choice; just make sure it's part of a diverse, balanced diet. It’s still a rich source of antioxidants and heart-healthy compounds.

References:

1. Allison Wing et al. “Dietary Oleic Acid Drives Obesogenic Adipogenesis via Modulation of LXRα Signaling.” Cell Reports 44, no. 4 (2025): 115527. https://doi.org/10.1016/j.celrep.2025.115527

2. University of Oklahoma. "This 'Healthy' Fat May Secretly Be Fueling Obesity." ScienceDaily, last modified on June 11, 2025. https://www.sciencedaily.com/releases/2025/06/250611084111.htm

(Rehash/Dr. Hansini Bhaskaran/MSM)