Obesity is a chronic disease with a high prevalence worldwide that is generally associated with a multitude of health complications.

Scientific data show that this phenomenon seems to be increasing in recent years, so it has become a public health problem, especially in developed countries.

Overweight: a worrying reality…

The World Health Organization (WHO, 2015) states that
1.9 billion adults in the world are overweight , of which more than 600 million are obese. In Spain, obesity has also become a serious problem, and this is confirmed by data from the ENRICA study, which concludes that 39% of the Spanish population is overweight and 22.9% obese.

Due to the complexity of this phenomenon, the most effective treatment to combat this condition consists of three basic pillars:
nutrition, psychological aspects and physical exercise .

Causes of Obesity

Obesity is a multi-causal phenomenon and therefore the causes are due to several factors:
those of genetic and endocrine origin, which account for 30%, and those of environmental origin, which represent 70% .

The latter include excessive food intake, especially unhealthy products, lack of physical exercise and, in general, a sedentary lifestyle.

Obesity and serious health problems

Obesity brings about serious health problems for people affected by this condition . As Miguel Soca and Niño Peña conclude in a study carried out in 2009: “Obesity can cause a set of metabolic abnormalities, called metabolic syndrome (MS): a series of disorders characterised by glucose intolerance, diabetes, alterations in blood lipids and increased blood pressure”.

Likewise, obesity negatively affects life expectancy and quality of life, as well as body aesthetics which, consequently, can cause social and psychological problems for the individual with this condition.

Diagnosis of obesity

Obesity is diagnosed, more than by weight, by the individual’s percentage of body fat. Generally speaking, in adult men, approximately 12-20% of their body weight is made up of fat. In the case of women, the percentage is a little higher, 20-30 %, mainly due to hormones such as estrogen.

Currently, there are different methods to quantify the percentage of body fat. Biompedance, X-ray engineering or densitometry are some examples. However, one of the most used methods is the Body Mass Index (BMI), obtained by the relationship between weight expressed in kilograms and height in meters squared (BMI: Weight/Size2). With the result of this index
is defined as overweight to individuals with a BMI equal to or greater than 25 kg/m2 and obese to those with a BMI equal to or greater than 30 kg/m2 .

Calculating the percentage of body fat

BMI is an easily obtained measure, with a high correlation to body composition, and is useful as a diagnostic value. In addition,
the higher the BMI of an individual, the greater the possibility of developing morbidities associated with excess fat . However, BMI has its limitations and has been criticized for not allowing differentiation between the percentage of fat and muscle mass.

If we consider the percentage of fat mass, obesity corresponds to a fat percentage greater than 25% in men and 30% in women. To estimate the percentage of body fat, skin folds are a very valid option. With this method it is necessary to make the sum of four folds: the bicipital, tricipital, subscapular and supra-iliac

Finally, another measure used for the diagnosis of obesity is the waist-hip index (WHI), a specific anthropometric tool for measuring intra-abdominal fat levels. This formula allows us to divide the waist perimeter by the hip perimeter (WHI: waist perimeter in centimeters/hip perimeter in centimeters). The WHO establishes normal levels for the waist-hip index of approximately 0.8 in women and 1 in men.

Types of obesity

Obesity can be classified in different ways depending on the criteria established . One of the most commonly used classifications is according to body fat distribution, in which there are three categories. According to the SEEDO Consensus (2007), they are the following:

1. Homogeneously distributed obesity

Excess fat does not predominate in any area of the body, which is why it is called evenly distributed obesity.

2. Ginoid or peripheral (pear-shaped) obesity

The fat is basically located in the hips and thighs. This type of distribution is mainly related to venous return problems in the lower extremities (varicose veins) and to knee arthrosis. Women are more likely to suffer from this type of obesity.

3. Android, central or abdominal (apple-shaped) obesity

The excess fat is located in the area of the face, chest and abdomen. It is associated with an increased risk of dyslipemia, diabetes, cardiovascular disease and mortality. This type of obesity is more common in men than in women.

Other classifications of obesity

In addition to the above classification, there are others such as the following

Types of obesity by degree of risk

According to the consensus of the Spanish Society for the Study of Obesity (SEEDO 2007), obesity can also be classified in the following way taking into account the BMI:

  • Underweight : The weight is below normal. BMI is less than 18.5 kg/m2. It is not considered overweight.
  • Normopeso : Is the normal weight of a person in relation to his height. The BMI is the ideal one: 18.5-24.9 kg/m2. It is not considered overweight.
  • Overweight : Overweight occurs when a person weighs more than he/she should according to his/her height. BMI 25-26.9 kg/m2.
  • Overweight II : A person is heavier than he/she should be for his/her height but not obese. BMI 27.29.9 kg/m2.
  • Obesity type I : First degree of obesity. BMI 30-34.9 kg/m2.
  • Obesity type II : Second degree of obesity BMI 35- 39.9 kg/m2.
  • Type III obesity : This type of obesity is also called morbid obesity. BMI 40-49.9 kg/m2.
  • Type IV obesity : This type of obesity is also known as extreme obesity. BMI over 50 kg/m2.

Types of obesity by cause

Depending on the source of the obesity, it can be

  • Genetic obesity : the individual has received the genetic inheritance or predisposition to have obesity.
  • Dietary obesity : characterized by a sedentary lifestyle and unhealthy food intake.
  • Obesity by mismatch : The person never feels satiated by a mismatch in the hunger regulation system.
  • Obesity by thermogenic default : The organism by not burning calories efficiently.
  • Nervous obesity : Is the obesity caused by psychological problems such as anxiety, stress and depression.
  • Obesity due to endocrine diseases : Is the obesity caused by diseases of hormonal type, for example, hyperthyroidism.
  • Chromosomal obesity : This type of obesity is associated with chromosomal defects.

Bibliographic reference:

  • Rodriguez Artalejo F. (2011) Epidemiology of obesity in Spain: ENRICA study. V NAOS Convention. Madrid: Center for Biomedical Research Network Epidemiology and Public Health.