Despite fat’s bad reputation, the body needs fat to grow, produce energy and synthesize substances like hormones, according to the Merck Manual Home Health Handbook. Fat also acts as an insulator, protecting the body’s cells and organs, according to Iowa State University Extension and Outreach. Without fat, the body can't absorb nutrients, such vitamins A, D and E.
According the Merck Manual Home Health Handbook, fat is a slow-burning and efficient form of energy. Each gram of fat contains nine calories, containing more than two times the number of calories provided by protein and carbohydrates.
Fat also ushers fat-soluble vitamins throughout the body, according to Iowa State University Extension and Outreach. On a cellular level, fat is also a precursor to body functions such as the production of vitamin D.
Iowa State University Extension and Outreach recommends a fat intake of less than 35 percent of the calories people consume. A diet of 2000 calories, for example, ideally contains 78 grams of fat at most. Two types of fat exist: saturated and unsaturated. High amounts of saturated fat are associated with elevated cholesterol levels. Because of this, less than 10 percent of calories consumed should come from saturated fat, which is found in foods such as butter, cheese and baked products. Unlike saturated fat, unsaturated fat is associated with lowering cholesterol levels. This type of fat is in olive oil, fish oil and flaxseed.