Common Cooking Oil Linked to Weight Gain and Metabolic Issues, New Research Shows
A recent study from the University of California, Riverside (UCR) has pinpointed a potential link between the widespread consumption of soybean oil and obesity, as well as related metabolic problems like fatty liver disease. While not inherently harmful, the sheer quantity of soybean oil in the modern American diet appears to be exceeding the capacity of our bodies to process it effectively.
The research, published in November 2023, builds upon earlier UCR findings from 2015 demonstrating that soybean oil promotes weight gain more readily than coconut oil. This latest examination goes deeper, identifying specific molecules created within the body after consuming soybean oil as key drivers of these effects.
The culprit isn’t the oil itself,or even its primary fatty acid,linoleic acid,but rather what linoleic acid transforms into: oxylipins. Excessive intake of linoleic acid leads to increased oxylipin production, wich is associated with inflammation and fat accumulation.
Researchers utilized genetically engineered mice with reduced levels of enzymes responsible for converting linoleic acid and alpha-linolenic acid (another fatty acid in soybean oil) into oxylipins.These altered mice exhibited healthier livers and enhanced mitochondrial function, demonstrating resistance to weight gain despite consuming a high-fat soybean oil diet. Crucially,the study found that oxylipin levels in the liver,not the blood,correlated with body weight,suggesting standard blood tests may miss early metabolic changes.
The study also revealed a surprising connection to cholesterol. Despite soybean oil containing no cholesterol, mice consuming it showed higher cholesterol levels.
The findings are particularly relevant given the dramatic increase in soybean oil consumption in the United states over the past century. In 1923, soybean oil accounted for approximately 2% of total calorie intake. Today, that number has risen to nearly 10%. This surge coincides with a rise in ultra-processed foods, which frequently utilize soybean oil.
“Soybean oil isn’t inherently evil,” explains Professor Pritpal Deol of UCR. “But the quantities in which we consume it is triggering pathways our bodies didn’t evolve to handle.”
Researchers are now investigating the mechanisms by which oxylipin formation leads to weight gain and exploring whether similar effects are observed with other oils high in linoleic acid, such as corn, sunflower, and safflower oil. While human trials are not currently planned, the UCR team hopes their research will inform future nutrition policy and public health awareness, drawing a parallel to the decades-long delay between identifying the link between tobacco and cancer and implementing warning labels.
Source: UC Riverside – https://news.ucr.edu/articles/2025/11/26/study-links-americas-favorite-cooking-oil-obesity
