A healthy diet has the right balance of food types. If the diet is unbalanced, a person can become malnourished. When you exercise, more energy is used by the body. The metabolic rate is the rate at which chemical reactions happen in cells. Exercise increases the metabloc rate. The metabolic rate is also affected by inherited factors and the muscle to fat ratio.
Eating too much can lead to health problems such as Type 2 diabetes. It can make you overweight and obese and this can lead to mental problems as well as physical problems. If the energy intake is greater than the energy output, the mass increases. Weight problems are reduced by eating less carbohydrate and exercising more. Some people are unhealthy because they don't eat enough. This leads to starvation and can cause deficiency disease, due to a lack of certain vitamins or minerals in the diet. The person would find it difficult to move about.
The metabolic rate is affected by inherited factors. We have both 'good' and 'bad' levels of cholesterol in our bodies. The good cholesterol makes vital substances and is required in cell membranes. However, high levels of bad cholesterol are inherited by small numbers of the population and leads to heart disease. Foods rich in saturated fat increase the blood cholesterol levels. Regular exercise increases the metabolic rate and lowers blood cholesterol levels.
Pathogens are tiny microorganisms that cause infectious diseases. They mainly exist as bacteria and viruses. These reproduce rapidly inside the body and can produce toxins that make you feel ill. Viruses are much smaller than bacteria and reproduce inside body cells. The damage they cause to the cells also makes you feel ill. Before pathogens had been discovered, a doctor called Semmelweiss realised that infection could be transferred from person to person in a hospital. He advised his staff to wash their hands between treating patients, but his ideas weren't universally accepted.
The skin stops pathogens getting into the body. They are also killed by stomach acid and trapped by mucus. White blood cells are part of the…