From the Latin obesity (excess weight), obesity is a disease characterized individuals whose body fat is very important, which has the effect of subjecting to deficiencies cardiovascular, diabetes, etc.. It affects more and more people in developed countries and is considered a pandemic, although it is not an infectious disease.

Obesity is caused by several factors inherent to humans. It now has sufficient resources to feed or food excessively. In addition, the society brings a lot of sedentary individuals, who no longer have to spend to physically move or play. Indeed, in some individuals, intakes of carbohydrates, lipids and proteins are too large relative to their physical activity. This energy is then stored in the body as adipose tissue or fat. However, scientists have proven that a person may have genetic predispositions that increase the risk for him to become obese. Unlike most diseases that decimated the modern society, obesity affects mainly the developed countries. These are indeed areas where food is within reach for all, and where technological progress increases the sedentary individuals.

Obesity also leads to a predisposition to several deadly diseases. Thus, obese subjects are likely to report early diabetes, hypertension, sleep apnea, osteoarthritis, etc.. Obesity is also a risk for pregnant women, which may have a complicated pregnancy. Finally, obese individuals have a greater amount of tissue likely to be affected by cancer, and the probability of developing this disease is greatest. They are generally more vulnerable than those "normal". Obesity can also become a social ordeal for those who suffer, who are subject to discrimination and depression. This, coupled with the high mortality of obese people shows that this disease is a scourge for the people who are affected.

Doctors have no other solution to fight against obesity than prescribing schemes to those who suffer. When they detect a predisposition to disease, they warn the patient, to monitor their diet and activity, to prevent it becoming obese. Finally, in recent years, prevention campaigns against obesity have been established by the governments of countries affected by the disease. They advocate the consumption of fruit and vegetables daily and quantity in order to regulate food intake. They also encourage physical activity, sport or home regularly, to ensure the consumption of carbohydrates, lipids and proteins ingested. These campaigns raise awareness among adults but especially children, more prone to obesity. Moreover, children, if they acquire healthy eating habits from an early age are likely to keep throughout their life, and this limits their likelihood of becoming obese.