Metabolic syndrome is a cluster of cardiovascular disease and diabetes risk factors including elevated waist circumference, high blood pressure, elevated triglycerides, low levels of high-density lipoprotein, or HDL or "good" cholesterol and high fasting glucose levels. Three or more of these factors increases a person's risk of developing diabetes and cardiovascular disease.

"Fried foods are typically synonymous with commonly eaten fast foods, so I think it is safe to say that these findings support a link between fast-food consumption and an increase in metabolic risk factors," study co-author Lyn M. Steffen of the University of Minnesota said in a statement.

The researchers monitored the dietary intake of 9,514 study participants ages 45 to 64 years old using a 66-item food frequency questionnaire and after nine years nearly 40 percent had metabolic syndrome.

The study published in the journal Circulation: Journal of the American Heart Association, found meat, fried foods and diet soda were all significantly associated with increased risk of metabolic syndrome, but consumption of dairy products was beneficial.