The main function of fats is to provide energy, although minute amounts are used in growth and repair. Fats enable energy to be stored and they play a role in insulation. Most fats come from animal products, although some are found in plant foods such as olives, peanuts and avocados. Excess fat is laid down in the body as fatty tissue and is the main cause of obesity.
Depending on their chemical composition, fats are either saturated or unsaturated. Saturated fats are more likely to increase the amount of cholesterol in the body and therefore increase the risk of heart disease. Broadly speaking, animal fats, especially those in milk, butter, cheese and meat are highly saturated, and the fat in fish, chicken, turkey and vegetable products is unsaturated. Most of the fat in chicken and turkey is in the skin, which can be removed.
Cholesterol and triglycerides are types of fat that are found only in animal products such as meat, eggs and dairy products. These fats can also be manufactured by the body from other types of fat, and is essential in the body for the formation of many chemicals including sex hormones. The rate at which cholesterol and triglyceride are manufactured by the body is determined to a considerable extent by inheritance. Excess levels of these fats in the blood stream can cause hardening of the arteries, heart attacks and strokes.