Fast food is the generally accepted term for food sold in restaurants that emphasize easy ordering, rapid preparation and quick service for their customers. Many of the foods served in these restaurants contain substantial amounts of two forms of fat — saturated fat and trans fat. Studies have shown that regular consumption of these fats can significantly increase your chances of developing symptoms of depression. Consumption of baked goods that contain these fats can also increase your depression risks. Saturated Fat Basics Saturated fat is a naturally occurring form of fat found primarily in meats such as beef, pork and lamb, as well as in other animal products such as cheese, butter, whole milk and lard. Additional plant sources of this fat include coconut oil, palm oil and palm kernel oil. Doctors and nutritionists typically warn against excessive consumption of saturated fat because its presence in your diet will increase the amount of harmful LDL cholesterol in your bloodstream, the American Heart Assn. explains. In addition, foods that contain this type of fat also frequently contain significant amounts of cholesterol on top of their saturated fat content. Foods high in saturated fat are regularly featured in fast food restaurants across the U.S. and around the globe. Trans Fat Trans fat (also known as partially hydrogenated vegetable oil) is not found in nature; instead, it comes from the chemical manipulation of naturally occurring vegetable oil. Typically, food manufacturers rely on this man-made fat to increase the amount of time their products can stay on store shelves; they also use it to decrease the greasiness usually associated with fat-containing foods. Specific types of foods that frequently contain trans fat include margarine, vegetable shortening and fried or baked goods such as doughnuts, cakes and cookies. The French fries served in fast food restaurants also frequently contain this fat. The process used to make trans fat results in a higher-cholesterol product than natural fat, the Mayo Clinic explains. In addition, the human body apparently has a harder time breaking down this man-made fat than it does breaking down natural fat. Fat Consumption and Depression In a study published in 2011 in the journal PLOS ONE, a team of Spanish researchers followed more than 12,000 people over a six-year period in order to assess the link between fat consumption and depression. At the start of the study, none of these participants had depression symptoms; by the end of the study, 657 participants had these symptoms. After reviewing their findings, the authors of the study concluded that people who regularly consume trans fat have a 48 percent higher chance of developing depression than people who don’t consume this type of fat. In addition, the authors concluded that a person’s depression risks rise as his or her consumption of trans fat rises. In other words, people with relatively low trans fat intake experience relatively modest increases in their depression risks, while people with relatively high trans fat intake experience relatively prominent increases in their depression risks. Fast Food Consumption and Depression In a second study, published in 2012 in the journal Public Health Nutrition, the same group of researchers examined the effects of fast food consumption in almost 9,000 people with no previous history of depression. Six months into the study, almost 500 of these people had developed depression symptoms. The study’s authors reviewed their findings and concluded that, compared to people who rarely eat fast food or don’t eat fast food at all, regular consumers of fast food have a 51 percent higher chance of developing depression. As is true with trans fat consumption, the risks for depression rise along with the proportion of fast food contained in a person’s diet. Considerations In addition to assessing the depression-related risks of fast food consumption, the authors of the study in Public Health Nutrition assessed the depression-related risks of consuming commercial baked goods (which often contain trans fat). They concluded that even modest consumption of these goods can substantially increase a person’s chances of developing depression symptoms. As part of the study published in PLOS ONE, the Spanish research team examined the relationship between depression and the consumption of healthier types of fat such as monounsaturated fat and polyunsaturated fat. They concluded that regular intake of these fats modestly decreases a person’s chances of developing depression.