Fats provide energy. Gram for gram fats are the most efficient source of food energy. Each gram of fat provides nine calories of energy for the body, compared with four calories per gram of carbohydrates and proteins.
Fats build healthy cells. Fats are a vital part of the membrane that surrounds each cell of the body. Without a healthy cell membrane, the rest of the cell couldn’t function.
Fats build brains. Fat provides the structural components not only of cell membranes in the brain, but also of myelin, the fatty insulating sheath that surrounds each nerve fiber, enabling it to carry messages faster.
Fats help the body use vitamins. Vitamins A, D, E, and K are fat-soluble vitamins, meaning that the fat in foods helps the intestines absorb these vitamins into the body.
Fats make hormones. Fats are structural components of some of the most important substances in the body, including prostaglandins, hormone-like substances that regulate many of the body’s functions. Fats regulate the production of sex hormones, which explains why some teenage girls who are too lean experience delayed pubertal development and amenorrhea.
Fat provides healthier skin. One of the more obvious signs of fatty acid deficiency is dry, flaky skin. In addition to giving skin its rounded appeal, the layer of fat just beneath the skin (called subcutaneous fat) acts as the body’s own insulation to help regulate body temperature. Lean people tend to be more sensitive to cold; obese people tend to be more sensitive to warm weather.
Fat forms a protective cushion for your organs. Many of the vital organs, especially the kidneys, heart, and intestines are cushioned by fat that helps protect them from injury and hold them in place. (True, some of us “overprotect” our bodies.) As a tribute to the body’s own protective wisdom, this protective fat is the last to be used up when the body’s energy reserves are being tapped into.