What is Obesity?

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Obesity is a chronic disease, caused by different factors, and is of high prevalence, which is associated with a higher risk of developing cardiovascular diseases, a reduction in the quality of life, and an increase in mortality. 

The World Health Organisation (WHO) defines obesity as an abnormal accumulation of fat that can be detrimental to health.

Obesity explained in first person

Professionals and patients explain how you live with the disease
Obesity is the result of an energy intake–consumption imbalance; that is, individuals consume more calories than they burn. However, obesity is much more complicated than this simple equation and multiple factors play a part in its appearance.
Never forget where you were before, because you can always end up back there.

Types of Obesity

In adults, the international classification of obesity is that proposed by the WHO, and is based on the Body Mass Index (BMI). Those persons with a calculated BMI equal to or higher than 30 kg/m2 (same for both sexes) are considered to be obese.

Obesity is also classified according to the distribution of adipose tissue in:


Person with fat accumulation in neck, shoulders and abdomen

Abdominal obesity, visceral. Also called android type, with a predominance of adiposity in the upper half of the body: neck, shoulders, and abdomen. This type of obesity is associated with an increase in the risk of metabolic diseases (type 2 diabetes, atherosclerosis, etc.).

Person with fat accumulation in buttocks

Gluteal-femoral or gynoid obesity. With a predominance of adiposity in the gluteals, hips, thighs, and the lower part of the body.

The strong relationship between fat distribution at abdominal level and cardiovascular disease has led to the clinical acceptance of indirect indicators of abdominal fat, such as the measurement of the waist circumference. The points of reference in Europe for considering abdominal obesity are different in both sexes: in men over 94 centimeters and in women 88 centimeters.

Is Obesity very common?

According to estimations of the WHO, in 2016, more than 1,900 million adults of 18 years or more were overweight, of whom, more than 650 million were obese.

In general, in 2016, around 13% of the world adult population (11% of the men and 15% of the women) were obese.

Between 1975 and 2016, the world prevalence of obesity has almost tripled.

In Spain, in a study published in 2016 (Aranceta-Bartrina) with measured data showed that: 

  • The estimated prevalence of overweight in the Spanish adult population (25-64 years) is 39.3% (95% confidence interval [95% CI95%], 35.7-42.9%);  

  • That of general obesity, 21.6% (95% CI, 19.0-24.2%), 22.8% (95% CI, 20.6-25.0%) among males and 20.5% (95% CI, 18.5-22.5%) among females, and increases with age.  

  • The prevalence of abdominal obesity was estimated at 33.4% (95%CI, 31.1-35.7%), higher among females (43.3%; 95%CI, 41.1-45.8%) than among males (23.3%; 95%CI, 20.9-25.5%), and also increased with age.

Related contents

Substantiated information by:

Alba Andreu Martí
Lilliam Flores Meneses
Silvia Cañizares Alejos

Published: 17 August 2018
Updated: 20 January 2022

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