That “ketosis” condition permits the liver to break down lipids into molecules known as ketones. Those ketones offer the energy required.There are three major fat categories – Polyunsaturated fats, Saturated fats, and monounsaturated fats.Saturated fats were once thought to be bad for health, with a definite link between them and heart disease. However, they have been demonstrated to NOT trigger heart attacks and improve cholesterol levels. People should not be concerned about eating them.