Fats are a major source of energy in the diet, and provide twice as many calories as protein or carbohydrates for the same amount of weight. In developed countries, fat intake has increased at the expense of a reduction in complex carbohydrates. In order to lose weight, we almost always have to cut down on fat intake, but some fats are essential, just as vitamins and minerals are. These are the polyunsaturated fats, which are derived mainly from sunflower, safflower and rappelled oils, vegetables, nuts, seeds and some fish.
Foods of animal origin, e.g. lard, dripping, butter, milk, cream, cheese, and meat, and some vegetable oils, notably palm oil and coconut oil, are rich in saturated fats. These are not essential, and have the undesirable effect of stimulating the liver to produce more cholesterol, and raising its level in the blood. Both saturated and polyunsaturated fats contain the same amount of calories. The sheer
Cholesterol is a specialized form of fat which is found particularly in eggs, dairy products and meat. Most of the cholesterol in our blood is actually made by our liver and approximately one-third is derived from our diet. Dietary cholesterol is not the ogre the experts once thought it was. Our dislike of late has turned quite rightly to an excess of animal fats, combined with a lack of fibre in the diet.
Approximately 15 per cent of our diet is composed of protein; 55 per cent is composed of carbohydrate, and 40 per cent of fat.
Vitamins and minerals are essential nutrients that are required not for their calorific value, which is negligible, but because they help regulate the body's metabolism. All vitamins and essential minerals are necessary to assist in normal functioning of the thousands of different chemical reactions that make up the body's metabolism. If the supply of vitamins and minerals in the diet is inadequate, this will result in changes in body chemistry, and a slowing down or altering of the body's metabolism, usually with some deterioration in body fitness or health. Vitamins and minerals often work together in this respect, and some are necessary for normal energy production, the use of protein in growth and tissue repair, and in many other functions, ranging from hormone production to effects on skin quality. Additionally, some minerals, particularly calcium, phosphorus and magnesium, are necessary with certain types of protein for the formation of the skeleton.
Fibre is a specialized form of complex carbohydrate, which cannot be broken down by the normal human digestive system. It thus becomes a major constituent of the waste product, faeces. Diets high in fibre are often high in vitamins and minerals, and a high-fibre diet is an important part of a weight-reduction programme.