Fats are also called lipids or triglycerides and can be roughly divided into saturated and unsaturated types.
An important nutrient, fat is burned for energy, essential for absorption of fat-soluble vitamins A, D and E and used as insulation to keep the body warm.
Although there is no RDA for fat, many experts recommend consuming at least 15 percent of the diet from unsaturated fats to ensure sufficient intake of essential fatty acids.
Fat was broadly denounced as a cause of high cholesterol in the 1970s, but research into the value of fat has recently increased amid a resurgence in low-carbohydrate diets.
The body can become deficient in fat through long-term consumption of too little calories, causing the body to burn fat stores for energy, or through a very low-fat diet that also forces the body to utilize its stores of fat.
Wasting, either through AIDS or cancer, can also result in fat deficiency. Alcohol and drug abuse can make the body deficient in fat by inducing metabolic problems and starvation.
Finally, fat deficiency can occur through fat malabsorption, a common issue in celiac disease patients, whose intestines lack healthy cilia crucial for normal absorption of fat and other nutrients.
Many modern weight loss researchers have stated that an excess of fat is present in individuals whose body mass index exceeds the accepted normal range regardless of bone structure.
In people with hypothyroidism, fat may accumulate to high levels because their metabolism is too low to burn the fat for energy. Type 2 diabetes is associated with an excess of body fat because of high levels of insulin, which facilitates fat storage.
Alcoholism and high-sugar, high-fat diets can cause fat accumulation in the liver in cases of alcoholic and non-alcoholic fatty liver disease, respectively.