What is obesity ?

What is obesity?

In 1997, the WHO classified obesity as a chronic disease, and defined “overweight and obesity as an abnormal or excessive accumulation of body fat, which presents a risk to health.” Its prevention is a public health problem in all developed countries, and even in developing countries where obesity is now also present. Obesity is also considered a disease in the following countries: Portugal, France, Holland, Malta, Canada and the USA. In 2016, the WHO said more than 1.9 billion adults – people 18 and older – were overweight. Of this total, more than 650 million were obese, 39% of adults aged 18 and over were overweight in 2016, and 13% were obese. In this context, we, patients and healthcare professionals, offer this obesity chart. Overweight and obesity are major risk factors for a number of chronic diseases, including diabetes, cardiovascular disease and cancer. Once considered a problem only in high-income countries, overweight and obesity are now dramatically on the rise in low- and middle-income countries, particularly in urban settings. In 2019, 55% of Swiss people are overweight, nearly one in ten people suffer from obesity.

What are the health consequences of excess weight?

The latest WHO projections show that at least one in three adults worldwide is overweight and nearly one in 10 is obese. In addition, there are over 40 million children under the age of five who are overweight.

Being overweight and obese can have serious health consequences. The excess fat can in particular cause cardiovascular disease (mainly heart disease and stroke), type 2 diabetes, musculoskeletal disorders such as osteoarthritis, and certain cancers (endometrial, breast and colon). These diseases cause premature death and significant disability.


The controversy over whether or not obesity is a disease goes back to about a century ago. However, after observing a devastating pandemic, it’s necessary to take drastic measures to stop it. Most experts (in 2019) claim obesity to be a disease that is:

Chronic: it evolves over the long term and requires lifelong treatment.

Complex: it involves both metabolic, somatic and psycho-behavioral, psychiatric and social attacks as well as genetic problems.

Progressive: it often evolves stealthily into different pathologies that can appear progressively in varying degrees and extent depending on the patients, their genetic susceptibility, their environment and their behavior.

Recurrent: regardless of the treatment used to treat obesity, weight gain is seen soon after the lost weight stabilizes, whether following conservative treatment or bariatric surgery. Long-term stabilization of weight loss is rare and requires lifelong monitoring. Weight gain is not always dependent on the extent of the weight lost (yo-yo risk).


  1. Its symptoms and pathognomonic clinical signs are recognized by experts.
  2. It causes many severe comorbidities that require priority medical treatment.
  3. Even in the absence of signs, symptoms, or laboratory pathology, patients with obesity are at higher risk of developing cardiovascular disease than the general population of normal weight.

The patient with obesity will usually suffer from stigma; this leads to exacerbating obesity and a vicious cycle.
Its origin is multigenic (hereditary transmission)