You must have fat in your diet. Scientists generally recommend that a healthy diet should contain no more than 30% fat. More ascetic recommend 20% but a diet with 10% fat or lower is founded to be dangerous. If you cut all fat you will die for sure because you will miss essential fatty acids (EFA) that keep you in good health by improving the immune system condition and helping the absorption of beta-carotene and vitamins A, D, K.

But fats are not all equal useful.

The monounsaturated fats are the healthiest of all. They act increasing your good HDL levels of cholesterol while bad LDL is lowered. Monounsaturated fats are extracted especially from macadamia, other nuts, olive oil, and canola oil. They are stable under the action of heat and this characteristic makes them far more suitable for frying.

In the second place comes polyunsaturated fats, which are found in avocados, soy, sunflower and flax seeds and other vegetables as well as salmon, mackerel and sardines. They contain the important group of EFA's which body can't synthesize. Polyunsaturated fats help lower your LDL cholesterol but do not have a significant influence on your HDL. They are good for health but require attention because are very unstable under heat and light. Then refrigerate them and use them cold.

The saturated fats are on the last place. You should know that they aren't absolutely bad for your health. What could be bad is the lack of right balance, favoring saturated fats consumption in detriment of unsaturated.