at least if you're a mouse--
From Eureka Alert:
http://www.eurekalert.org/pub_relea...--soc072015.php
Soybean oil causes more obesity than coconut oil and fructose
UNIVERSITY OF CALIFORNIA - RIVERSIDE
RIVERSIDE, Calif. -- A diet high in soybean oil causes more obesity and diabetes than a diet high in fructose, a sugar commonly found in soda and processed foods, according to a just published paper by scientists at the University of California, Riverside.
The scientists fed male mice a series of four diets that contained 40 percent fat, similar to what Americans currently consume. In one diet the researchers used coconut oil, which consists primarily of saturated fat. In the second diet about half of the coconut oil was replaced with soybean oil, which contains primarily polyunsaturated fats and is a main ingredient in vegetable oil. That diet corresponded with roughly the amount of soybean oil Americans currently consume.
The other two diets had added fructose, comparable to the amount consumed by many Americans. All four diets contained the same number of calories and there was no significant difference in the amount of food eaten by the mice on the diets. Thus, the researchers were able to study the effects of the different oils and fructose in the context of a constant caloric intake.
Compared to mice on the high coconut oil diet, mice on the high soybean oil diet showed increased weight gain, larger fat deposits, a fatty liver with signs of injury, diabetes and insulin resistance, all of which are part of the Metabolic Syndrome. Fructose in the diet had less severe metabolic effects than soybean oil although it did cause more negative effects in the kidney and a marked increase in prolapsed rectums, a symptom of inflammatory bowel disease (IBD), which like obesity is on the rise.
The mice on the soybean oil-enriched diet gained almost 25 percent more weight than the mice on the coconut oil diet and 9 percent more weight than those on the fructose-enriched diet. And the mice on the fructose-enriched diet gained 12 percent more weight than those on a coconut oil rich diet.
"This was a major surprise for us - that soybean oil is causing more obesity and diabetes than fructose - especially when you see headlines everyday about the potential role of sugar consumption in the current obesity epidemic," said Poonamjot Deol, the assistant project scientist who directed the project in the lab of Frances M. Sladek, a professor of cell biology and neuroscience.
Discussion from the end of the PLOS article:
There is currently considerable debate in both the scientific literature as well as the lay press as to which components of the American diet are the most obesogenic. Since diet studies in humans involve a large number of variables, most of which cannot be properly controlled, in this study we used mice and precisely defined isocaloric diets to compare the metabolic effects of saturated fat from coconut oil, unsaturated fats from soybean oil and fructose. To our knowledge, this is the first study not only to compare the effects of these three dietary factors in mice, but also to perform genome-wide expression profiling and metabolomics analysis of livers from animals fed a soybean-oil enriched diet. Our results indicate that, contrary to expectation, PUFA-rich soybean oil is more obesogenic and diabetogenic than coconut oil which consists of primarily saturated fat. They also show that fructose is less obesogenic than soybean oil and reveal a striking fatty liver morphology induced by soybean oil as well as a global dysregulation of Cyp genes and disease-associated genes and metabolites in the liver. These effects in the mouse liver could be clinically relevant as NAFLD, a component of the Metabolic Syndrome, is estimated to be present in 20–30% of adults in the U.S. and 3–10% of children
This is the PLOS article:
http://journals.plos.org/plosone/ar...al.pone.0132672
Very lengthy and detailed study. Some jargon but a lot is pretty plain English. PLOS is pretty amazing. A lot of the data is appended if you'd like to look at the actual raw data from the study. Not that I recommend it...
I guess the problem with soybean Omega-6 oil is the pro-inflammatory nature of it.