Fat is one of the three macronutrients, or energy-providing molecules, that you need to fulfill cellular energy needs. However, there are several different types of fat, some of which are healthier than others. One of the less healthy types of fat is saturated fat, excessive consumption of which can increase risk of cardiovascular disease.
Fats
Chemically, the definition of a nutritional fat is that it's made up of three molecules called fatty acids, connected to one molecule called glycerol. Glycerol is closely related to alcohol, explain Reginald Garrett, Ph.D., and Charles Grisham, Ph.D., in their book "Biochemistry." Together, the fatty acids and glycerol make up a triacylglyceride, or fat molecule. Depending upon the kinds of fatty acids that go into making up a triacylglyceride, it is classified as a saturated fat, unsaturated fat or trans fat.
Saturated Fats
Specifically, saturated fats consist of glycerol and saturated fatty acids. A saturated fatty acid is a long chain of carbon and hydrogen atoms, with two oxygen atoms attached to one end. The carbon chain contains only single bonds between carbon atoms -- there are no double bonds. The lack of double bonds is the distinguishing characteristic of a saturated fat, explain Garrett and Grisham. Because of the lack of double bonds, saturated fats have long, stick-like shapes.
Physical Characteristics
Saturated fats have physical characteristics that arise from their lack of carbon-carbon double bonds. Because of their long, stick-like shapes, they pack easily into dense, compact structures with other molecules of saturated fat. This means they have high melting points, and are solid at room and body temperature. Humans use saturated fats as storage fats -- you store saturated fat in your fat cells -- because it's logistically easier to store a solid fat than a liquid fat.
Considerations
When you consume saturated fat, including the fat of warm-blooded animals and certain tropical plant oils, like coconut or palm oil, your body converts some of the saturated fat into cholesterol, explain Mary Campbell, Ph.D., and Shawn Farrell, Ph.D., in their book "Biochemistry." Specifically, consumption of saturated fat increases your blood concentration of low-density lipoprotein, which is colloquially called "bad" cholesterol. LDL increases your risk for heart disease and stroke.
Expert Insight
While saturated fat is solid at room temperature, which provides one mechanism for recognizing it in food sources, not all fat that is solid at room temperature is saturated fat, explain Campbell and Farrell. Another kind of fat, called trans fat, is also solid at room temperature. Sources of trans fat include margarine and shortening, or any fat or oil with the words "partially hydrogenated" in it. Trans fats are also bad for heart health and increase LDL levels.
References
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- "Biochemistry"; Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005
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