Though vegetable and seed oils have been under scrutiny for quite some time now, many still use them regularly. Specifically, soybean oil remains one of the most widely consumed cooking oils in the U.S., but new research suggests it could quietly be packing on pounds. Scientists at the University of California studied how different fats affect weight gain and metabolism in mice, focusing on soybean oil.
The study, published in the Journal of Lipid Research, suggests that soybean oil may play a direct role in promoting obesity, depending on how the body processes linoleic acid, a major omega-6 fat in the oil. Researchers fed mice a diet high in soybean oil and tracked how their bodies broke down this fat.
When consumed, linoleic acid is broken down into molecules called oxylipins. Higher intake leads to higher oxylipin levels, and certain oxylipins were linked to weight gain and fat accumulation in the liver of normal mice.
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A separate group of genetically engineered mice gained far less weight, despite being on the same diet. These mice had a slightly altered liver protein that affects hundreds of genes involved in fat metabolism and also changed how their bodies processed linoleic acid. As a result, they produced fewer of the oxylipins tied to weight gain and showed better mitochondrial function, which may help resist obesity.
“This may be the first step toward understanding why some people gain weight more easily than others on a diet high in soybean oil,” UCR biomedical scientist and corresponding study author Sonia Deol said in a news release. “Soybean oil isn’t inherently evil, but the quantities we consume are triggering pathways our bodies didn’t evolve to handle.”
Though human studies are still needed, the findings confirm that the type of oil you use in the kitchen may influence your waistline. For men trying to stay lean, swapping soybean oil for alternatives lower in linoleic acid, like olive or coconut oil, could be a smart move.
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