People who are working in a hardship job must be aware of their nutrition because their body is consuming high quantities of energy, which must be supplied to their body through their diet. Their physical effort to maintain a hard working level may be similar to that of athletes.

When muscles are stimulated by repetitive muscular actions such as sport training or physical effort in an active job, they develop and increase the size of their muscular fibres (increase the production of myofibre, mitochondria, etc.). These bigger and more developed muscles can achieve more powerful contractions. A balanced diet for these persons must take into account that the ir needs for nutrients depend on factors such as age, sex, physical activity, etc.

Our diet must include all different kind of nutrients, taking into account that carbohydrates (rice, bread, cereals, pasta) must be 50-60% of the calories of our diet. Another important group of nutrients are proteins (meat, fish, eggs, milk), which for an adult, in a well balanced diet, should be 10-15% of the calories in a diet. The rest of the energy needs must be supplied by fats, which should be 25-30%, and which are found in milk products, butter and oils.

Minerals are an important group of nutrients which are absolutely necessary for the correct performance and maintenance of the human body. Minerals are part of many different enzymatic systems; we need them for an efficient use of the nutrients and the energy supplied through the diet. It would not be useful to plan and design our diet if we don't provide the body with the means to obtain the maximum benefits from them.