Lipids are a varied group of molecules that include fats, oils, waxes, steroids, hormones, and some vitamins. Survey the fats that obsess us in our diets and body shapes, notably triglycerides in their saturated and unsaturated forms. Then explore the role lipids play in energy storage and cell membrane structure, and cover the multitude of health benefits of the lipid vitamins: A, D, E, and K.