Go ahead, grab a few packaged foods from your kitchen—commercial-made desserts, bread, salad dressing, mayo, veggie burgers—and examine the food labels. Chances are good you’ll find soybean oil in almost everything.
For years the popular additive and cooking oil was considered a better alternative to saturated fats, but new animal research suggests that when it comes to weight gain, soybean oil may be far worse than sugar, the food world’s current problem child.
To come to this finding, University of California researchers divided mice into four groups. All groups were fed diets comprised of 40 percent fat and were given the same number of calories. Where the diets differed was in the type of fat they were served. Two groups were fed a diet rich in coconut oil, a popular source of saturated fat. One of those two groups were also given fructose, a type of sugar. The other mice were given a soybean oil-heavy diet, equal to the amount a typical American consumes. One of the two soybean groups was also given fructose. The researchers discovered that mice on the soybean oil diet gained 25 percent more weight than mice on the coconut oil diet and 12 percent more than groups who were also given fructose. The mice on the soybean oil diet developed larger fat deposits and were more likely to become diabetic. Mice given fructose had similar, but less severe, health issues.
The researchers aren’t certain why soybean oil led to more weight gain than sugar, but it’s likely that soybean oil’s high omega-6 fatty acid content is to blame. Though our bodies need some omega-6s, excessive amounts can increase appetite and slow the rate at which the body burns fat, causing weight gain. Check your food labels to make sure your go-to processed foods aren’t filled with the stuff, and when you’re cooking at home, be sure to stick one a healthy cooking oil like one made from olives, coconut, or avocado.