Part 1: The importance of fat
The science of nutrition is highly complex and, even today, little is known about the vital part that fat plays in our health and well-being. Nutrients interact: a deficiency of one can have a profound effect on the metabolism of others. Today, a lack of dietary fat probably causes a wider range of abnormalities than deficiencies of any other single nutrient.
With some 9 kcals per gram, fat is the best source of energy, but it does much more than provide energy.
Restriction of dietary fat causes a range of problems including:
- dry skin and eczema,
- damage to ovaries in females,
- infertility in males,
- kidney damage,
- and weight gain through water retention in the body.
When there is little or no fat in the gut, there is nothing to stimulate the production of bile, the gall-bladder is not emptied and the bile is held in reserve. This leads to the formation of gallstones. If a fat-free diet is continued for a long time, the gall bladder - a necessary part of the digestive system - may atrophy.
Malabsorption of the fat-soluble vitamins A, D, E and K has consequences for yet more nutrients. If vitamin D and fat are not present in the intestine, for example, calcium is not absorbed. For a woman, whose chance of suffering from osteoporosis and osteomalacia is high, this is an important consideration.
Dieters are usually told to drink skimmed milk. This has the advantage, they are told, that it contains more calcium than full-cream milk. This is true, but skimmed milk does not contain fat. As a consequence, only about 5% of the calcium in skimmed milk is absorbed, compared to around 25% from semi-skimmed milk and 50% from full-cream milk.
This small absorption of calcium is reduced still further if the skimmed milk is eaten with a bran-laden breakfast cereal. Calcium-enriched milk sold in supermarkets may seem worth the extra expense but, as it is invariably calcium-enriched skimmed milk, most of that extra calcium is simply excreted without doing any good at all.