Oils and fats are the most concentrated energy food in our diet.
The 1994 review of nutritional aspects of heart disease suggests a maximum proportion of energy from fat of 35% of the dietary energy intake, and a maximum of 10% from saturated fat. The best level is much lower than this, but a very low fat diet is equally unhealthy.
Olive oil is produced from the ripe fruit of the olive tree. The best quality is cold pressed, and is a rich green colour. It is known as virgin olive oil. It should be stored in a dark and cool place but not in a refrigerator. It contains no cholesterol.
Butter is made by separating the milk fat from the liquid. It is 80% fat and contains almost no protein. It should not be excluded from the diet as it is an excellent natural source of vitamin E, but ration yourself to 4oz / 100g of butter in a week.