How do triglycerides differ from phospholipids and sterols?

Triglycerides account for roughly 99 percent of the lipids stored in your body and 95 percent of the lipids found in foods, according to “Understanding Normal and Clinical Nutrition.” Your digestive system breaks down the triglycerides in the foods you eat into their separate components: glycerol and fatty acids. The body can utilize these fatty acids as an immediate energy source or store them in the form of triglycerides for future or emergency energy needs. These triglycerides that are stored in the form of energy reserves reside primarily in adipose tissue, which has the additional function of insulating your body and protecting internal organs from injury. Adipose tissue also plays a role in maintaining optimal body temperature.

Phospholipids differ only slightly from triglycerides in chemical structure. While each triglyceride molecule consists of glycerol and three fatty acids, each phospholipid molecule substitutes a phosphate for one of the three fatty acids. Phospholipids form the membrane that make up the outer layer of all human cells. They play a key role in determining what enters and exits every cell.

Sterols make up a wide array of body compounds that are vital to your health. Perhaps the most obvious of these is cholesterol, which comes in both good and bad varieties – high-density lipoprotein, or HDL, and low-density lipoprotein, or LDL, respectively. Too much LDL and not enough HDL can cause an unhealthy buildup of plaque on the walls of your arteries, raising the risk of coronary heart disease and/or stroke. Other sterols in the body include bile acids, sex hormones such as testosterone, adrenal hormones such as cortisol and vitamin D.