Every body cell contains some form of lipid, and lipids perform critical roles in the body. They store energy, support the cell walls, and store or circulate the fat-soluble vitamins: A, D, E, and K. Fat is a necessary source of energy, and it also helps to make the foods we eat palatable.
And essential fatty acids are necessary for maintaining healthy cell walls, for normal cholesterol metabolism, and in the formation of important cell regulators called prostaglandins, hormone-like compounds that are involved in a wide variety of functions, such as regulation of blood pressure and blood coagulation.

Although lipids take an important role in maintaining our heath, but it may cause another big problem---Obesity.
Because fat sources usually contain little water and take up less volume than protein or carbohydrate, we can eat more fat without feeling full. And because of its chemical nature, fat contains more calories per gram than other foods. It also takes less energy to store excess fat calories as body fat than those that come from carbohydrates and protein. So it may be easier to get fat on a high-fat diet.
Obesity increases the risk for high blood pressure and consequently for stroke. It is also associated with an increase in blood cholesterol, which is associated with heart disease. In addition, obesity is a critical causal factor in Type II diabetes, the most common form of diabetes.