Saturated fat is fat that consists of triglycerides containing only saturated fatty acids.

Saturated fatty acids have no double bonds between the carbon atoms of the fatty acid chain; hence, they are fully saturated with hydrogen atoms.

There are several kinds of naturally occurring saturated fatty acids, their only difference being the number of carbon atoms - from 1 to 24. Some common examples of saturated fatty acids are butyric acid with 4 carbon atoms (contained in butter), lauric acid with 12 carbon atoms (contained in breast milk, coconut oil, palm oil), myristic acid with 14 carbon atoms (contained in cow milk and dairy products), palmitic acid with 16 carbon atoms (contained in palm oil, hence the name, and meat), and stearic acid with 18 carbon atoms (also contained in meat and cocoa butter).

Fat that occurs naturally in living matter such as animals and plants is used as food for human consumption and contains varying proportions of saturated and unsaturated fat. Foods that contain a high proportion of saturated fat are butter, ghee, suet, tallow, lard, coconut oil, cottonseed oil, and palm kernel oil, dairy products (especially cream and cheese), meat, chocolate, and some prepared foods.

While nutrition labels usually lump them together, the saturated fatty acids appear in different proportions among food groups. Lauric and myristic acids are most commonly found in "tropical" oils (e.g. palm kernel, coconut) and dairy products. The saturated fat in meat, eggs, chocolate and nuts is primarily palmitic and stearic acid.

Saturated fat is easy to recognize because it is usually solid at room temperature. Other fats, such as polyunsaturated fat and monounsaturated fat, are found in vegetable oils. These fats are liquid or very soft at room temperature.

Diets high in saturated fat are correlated with an increased incidence of atherosclerosis and coronary heart disease according to a number of studies. Numerous studies have suggested that diets high in saturated fat increase the risk of heart disease and stroke. Epidemiological studies have found that those whose diets are high in saturated fatty acids, including lauric, myristic, palmitic, and stearic acid, had a higher prevalence of coronary heart disease. Additionally, controlled experimental studies have found that people consuming high saturated fat diets experience negative cholesterol profile changes. A 2003 meta-analysis published in the American Journal of Clinical Nutrition concluded that diets high in saturated fat negatively affected cholesterol profiles - predictors of a heart attack and other cardiovascular diseases.

Experiments in which subjects were randomly assigned to either a control or Mediterranean diet (which replaces saturated fat with mono and polyunsaturated fat) showed a significantly decreased likelihood of suffering a second heart attack, cardiac death, heart failure or stroke.

Epidemiological studies of heart disease have implicated the four major saturated fatty acids to varying degrees. The World Health Organization has determined that there is "convincing" evidence that myristic and palmitic acid intake increases the probability, "possible" risk from lauric acid, and no increased risk at all from stearic acid consumption.

It is the saturated fat in food that has the greatest negative effect on blood cholesterol level. Saturated fat raises bad cholesterol (Low Density Lipoprotein - LDL). One place where cholesterol causes trouble is in the walls of blood vessels. Too much cholesterol can make the blood vessel brittle or can block the flow of blood. The more saturated fat consumed, the higher cholesterol will rise. Saturated fat is also linked to higher levels of breast cancer.

A 2004 statement released by the Centers for Disease Control (CDC) determined that "Americans need to continue working to reduce saturated fat intake..." Additionally, reviews by the American Heart Association led the Association to recommend reducing saturated fat intake to less than 7% of total calories according to its 2006 recommendations. This concurs with similar conclusions made by the World Health Organization (WHO) and the US Department of Health and Human Services, both of which determined that reduction in saturated fat consumption would positively affect health and reduce the prevalence of heart disease.

The World Health Organization has concluded that saturated fats negatively affect cholesterol profiles, predisposing individuals to heart disease, and recommends avoiding saturated fats in order to reduce the risk of a cardiovascular disease.