Obesity corresponds to an excess of fatty mass having harmful consequences for health. It is a chronic disease that results from an imbalance between energy intake and expenditure. It leads to many medical, psychological and societal complications.

Obesity is determined from body mass index (BMI). BMI is the weight (in kg) divided by the square of the height (in meters). When the BMI is greater than 25 we speak of overweight and beyond 30 of obesity where there are several grades of severity.

Causes / Risk factors

The causes of obesity are multiple and complex. They can be genetic in certain forms of rare obesity.

Diet, psychological and environmental factors are also important causes for the development of obesity. More recently, the change in the intestinal microbiota has been increasingly mentioned.


According to the WHO, 39% of adults aged 18 and over were overweight in 2016 and 13% were obese and the number of obese people has tripled in the last 50 years.

In France, obesity affects 17% of the adult population.

This pathology also increasingly affects children and adolescents. Among those under 18, it affects 16% of boys and 18% of girls.

Evolution / Consequences

When obesity is permanently installed, we can speak of a chronic disease . It has many harmful consequences on health and is responsible for the development of other pathologies such as type 2 diabetes, sleep apnea syndrome, hypoventilation-obesity syndrome, arterial hypertension, cardiovascular diseases, kidney damage , etc. Obesity is also associated with an increased risk of cancer , particularly of the breast but also of the uterus, colon and liver. Obesity can also lead to degenerative osteo-articular problems (osteoarthritis) , sometimes severe and requiring the placement of a prosthesis for the joint concerned.

The onset or worsening of gastroesophageal reflux is also possible and the psychosocial impact of the disease should not be forgotten.

Finally, obesity is responsible for many deaths each year.

How is it treated?

It is necessary to set up a multidisciplinary care , personalized for each patient with a regular medical follow-up to push back or avoid the complications even to take care of the complications already present. This support also includes an adapted physical activity program, dietary monitoring which may involve culinary workshops to work on eating habits, food rhythm and nutritional balance and support for eating behavior disorders (psychologist /psychiatrist).

Drug or surgical treatment (sleeve, gastric bypass) can be proposed after nutritional support in patients with the most severe obesity, respecting the indications, contraindications and after having put in place an optimal preparation.

Is there research on this pathology?

Many areas of research in this area are underway (non-exhaustive list of examples):

  • Alterations in adipose tissue during obesity responsible for the development of obesity complications and even resistance to weight loss.
  • The role of the microbiota in obesity and its complications as well as therapeutic means to modulate this microbiota and improve metabolic health
  • The development of new drug treatments for common obesity but also for obesity from rare genetic causes
  • The beneficial effects of physical activity in the management of obesity…

ICAN's response

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