Final answer:
The primary form of lipid in the diet is triglycerides, which are made up of a glycerol backbone and three fatty acids and serve as the body's main energy storage form.
Step-by-step explanation:
The primary form of lipid in the diet is triglycerides. Triglycerides are composed of a glycerol backbone and three fatty acids. This type of lipid is the most common dietary lipid group and is also the type found most abundantly in body tissues. Phospholipids, on the other hand, are found predominantly in the plasma membrane of cells and consist of two fatty acids, glycerol, and a phosphate group. Steroids, like cholesterol, are lipids made up of four hydrocarbon rings and are vital for synthesizing certain hormones. While sterols and phospholipids play important roles in the body, it is the triglycerides that predominantly contribute to the body's energy stores.