Dieting and health

Food satisfies two distinct needs of the body. The first is for energy. A substantial amount of energy is needed just to maintain a constant body temperature and keep the heart, lungs, and the rest of the body’s mechanisms running. The energy consumed by a human body is comparable to a 100 watt light bulb. Food also supplies the raw materials the body uses to manufacture all the chemicals it needs, including those needed to build new cells. From the standpoint of energy, almost any food will do; you can assume that all foods with the same calorie content are interchangeable.

Eating the right mix of food only becomes important when you consider food as raw material. For the most part the body breaks food down into small molecules composed of carbon, hydrogen, oxygen, and nitrogen, and then manufactures what it needs from these building blocks. However, certain structures in the body require other constituents. For example, iron is needed to form the haemoglobin that carries oxygen in red blood cells, and calcium forms the matrix that strengthens bones. In addition, there are a number of complicated organic molecules our bodies require but cannot manufacture. These raw materials, minerals and vitamins, must be furnished or else the body begins to develop deficiency diseases such as scurvy and rickets.

If you eat a reasonable selection of food, varied from meal to meal, it’s extremely unlikely you’ll come up short one of those crucial substances (vegetarians have to be careful, as some nutrients abundant in meat are present only in a limited number of plant foods). The reason we focus entirely on calories when talking about weight control is that the energy-producing aspect of food is what determines whether you gain or lose weight. Unless your diet is wildly extreme, which particular foods you eat has very little effect on your weight compared to the total number of calories consumed.

If you supplement your food with a multivitamin every day (any one that provides 100% or more of the RDA of the big name nutrients is fine), you have even less cause for concern. Nevertheless, be reasonable. Just as any other extreme version of our everyday activities, an extreme diet (“clam juice and brown rice weight killer�?) can lead to certain risks.