A high-fat diet rich in oleic acid, the main fatty acid in olive oil, may do more than store energy. According to new research from the University of Oklahoma, it could actually increase the number of fat cells in the body, potentially raising the risk of obesity over time.
In a study published in Cell Reports, researchers found that mice fed diets high in oleic acid developed more fat cell precursors than those given other fats, including those found in coconut oil, lard and soybean oil. Oleic acid was the only fat that significantly accelerated fat cell formation.
“You can think of the fat cells as an army,” said lead author Michael Rudolph, PhD. “When you give oleic acid, it initially increases the number of ‘fat cell soldiers’ in the army, which creates a larger capacity to store excess dietary nutrients.”
The biological mechanism? High levels of oleic acid increased activity of a signaling protein called AKT2 and reduced the activity of LXR, a protein that normally slows fat cell development.
Oleic acid is a monounsaturated fat long considered heart-healthy when consumed in moderation, and it's a major component of olive oil, avocado oil and many high-oleic cooking oils. But the new findings suggest that prolonged or excessive intake may not be benign, especially when paired with calorie excess.
“Relatively balanced levels of oleic acid seem to be beneficial, but higher and prolonged levels may be detrimental,” Rudolph said.
He emphasized that most people consume a mix of fats daily, and variety may matter more than focusing on any one fat source.
This research was supported by the National Institute of Diabetes and Digestive and Kidney Diseases, the National Cancer Institute, the National Institute of General Medical Sciences, the National Science Foundation and the Ford Foundation. Additional support came from Women’s Health Research at Yale (Naratil Pioneer Award), Lo Fellowships for Excellence in Stem Cell Research and an EMBO postdoctoral fellowship. Core facility and equipment support was funded in part by NIH grants and shared instrument awards.