### New study reveals metabolic pathway linked to weight gain in mice.
Soybean oil is the most commonly used cooking oil in the united States and a frequent ingredient in processed foods, and research suggests it plays a role in promoting obesity in mice. Scientists are beginning to uncover the biological reasons behind this effect.
In a UC Riverside study, most mice fed a high-fat diet containing large amounts of soybean oil experienced notable weight gain. A separate group of genetically engineered mice did not. These modified mice produced a slightly different version of a liver protein that regulates hundreds of genes involved in fat metabolism. This altered protein also seems to affect how the body handles linoleic acid, the primary fatty acid found in soybean oil.
“This might potentially be the first step toward understanding why some people gain weight more easily than others on a diet high in soybean oil,” said Sonia Deol, a UCR biomedical scientist and corresponding author of the study published in the Journal of Lipid Research.
A Human Parallel: Two Forms of HNF4α
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Humans also produce two forms of the liver protein HNF4α, although the less common version usually appears only in specific situations, including chronic disease or metabolic stress caused by fasting or alcoholic fatty liver. This difference, combined with factors such as age, sex, medication use, and genetic background, may clarify why some individuals respond more strongly than others to the metabolic influence of soybean oil.
The study builds on earlier work by UCR researchers linking soybean oil to weight gain. “We’ve known as our 2015 study that soybean oil is more obesogenic than coconut oil,” said Frances Sladek, a UCR professor of cell biology. “But now we have the clearest evidence yet that it’s not the oil itself, or even linoleic acid. It’s what the f
Soybean Oil Linked to Weight Gain and Cholesterol Increase in New Study
A recent study from the University of California, Riverside (UCR) challenges the perception of soybean oil as a healthy fat, finding that it may contribute to weight gain and increased cholesterol levels. Published in the Journal of Lipid Research on October 28, 2025, the research suggests that the high linoleic acid content in soybean oil triggers metabolic pathways that the human body isn’t well-equipped to handle.
The Unexpected Findings
For decades, soybean oil has been widely used in processed foods due to its affordability and lack of cholesterol. Though, the UCR study, conducted on mice, revealed a surprising connection between soybean oil consumption and adverse health effects. Researchers discovered that the oil doesn’t simply remain inert; it’s metabolized into oxylipins, compounds that appear to disrupt normal metabolic processes.
Specifically, the study identified a key role for a protein called P2-HNF4α in altering linoleic acid metabolism and contributing to obesity when consuming soybean oil. The researchers found that soybean oil consumption led to higher cholesterol levels in the mice, despite the oil being cholesterol-free. This suggests that the issue isn’t the presence of cholesterol in the oil, but rather how the body reacts to its composition.
Oxylipins: The Culprit Behind Metabolic Disruption
The formation of oxylipins is central to the study’s findings. These molecules, created during the metabolism of linoleic acid, seem to interfere with the body’s natural regulatory mechanisms. The research team is currently investigating how these oxylipins contribute to weight gain and other metabolic disturbances.
“Soybean oil isn’t inherently evil,” explained Frances M. Sladek, a professor of chemistry and the lead author of the study. “But the quantities in which we consume it are triggering pathways our bodies didn’t evolve to handle.”
Implications for other vegetable Oils
The UCR team is expanding its research to determine if similar effects are observed with other vegetable oils high in linoleic acid, including corn, sunflower, and safflower oil. if these oils also promote oxylipin formation and metabolic disruption, it could have significant implications for dietary recommendations.
future Research and Policy Considerations
While the study was conducted on mice, the researchers hope their findings will inform future human trials and influence nutrition policy. They acknowledge the long road ahead, referencing the decades-long delay between the first links between tobacco and cancer and the implementation of warning labels.
“We hope it won’t take that long for society to recognize the link between excessive soybean oil consumption and negative health effects,” Sladek stated.
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