Overweight and obesity are defined as abnormal or excessive fat accumulation that may impair health.

Body Mass Index (BMI) is a simple indicator of body fat based on your weight and height that is commonly used to classify overweight and obesity in adults. It is defined as the body weight in kilograms divided by the square of the body height in meters (kg/m2).


In the case of adults, the OMS defines overweight and obesity as follows:

  • overweight: BMI equal or higher than 25
  • obesity: BMI equal or higher than 30

BMI provides the most useful measure of overweight and obesity among the population as it is the same for people of all ages and both genders. However, it should be considered a rough measurement since it may not correspond to the same size in different individuals.


In the case of children, it is important to keep age in mind when defining overweight and obesity. For children under 5 years of age:

  • overweight constitutes the weight-height measure with more than two standard deviations above the WHO Child Growth Standards median .
  • obesity constitutes the weight-height measure with more than three standard deviations above the WHO Child Growth Standards median.

In the case of children between the ages of 5 and 19, overweight and obesity are defined as follows:

  • overweight constitutes the BMI for the age with more than one standard deviation above the WHO Growth Standards median.
  • obesity is greater than two standard deviations above the WHO Growth Standards median.

Global Facts About Overweight And Obesity (Who)

  • In 2014, more than 1900 million adults aged 18 or over were overweight, 600 million of which were obese.
  • Overall, in 2014 around 13% of the world’s adult population (11% of men and 15% of women) were obese.
  • In 2014, 39% of adults aged 18 or over (38% of men and 40% of women) were overweight.
  • Between 1980 and 2014, the world’s prevalence of obesity has more than doubled.
  • In 2014, around 41 million children aged 5 were overweight or obese. Despite overweight and obesity once being considered a high-income-country problem, they are no won the rise in low-income and middle-income countries, particularly in urban settings.
  • In Africa, the number of children suffering overweight or obesity has practically doubled: de from 5,4 million in 1990 to 10,6 million in 2014. During the same year, near half of the children under the age of 5 suffering overweight or obesity lived in Asia.
  • Globally, overweight and obesity are linked to a greater number of deaths than underweight. Overall, there are more overweight people than underweight people. This happens in all regions except for sub-Saharan parts of Africa and Asia.


The principal cause for overweight and obesity is an energy imbalance between calories consumed and calories expended. Globally, there has been:

  • an increased intake of high-calorie foods that are high in fat; y
  • a decrease in physical activity result of the increasingly sedentary nature of many forms of work, new means of transportation and the ever-increasing urbanization.

More often than not, changes in diet and physical activity habits take place as a consequence of environmental and social changes associated with development and lack of support policies in sectors such as healthcare; agriculture; transportation; urban planning; environment; food processing, distribution and marketing; and education.


A high BMI is an important risk factor for non-communicable diseases such as:

  • cardiovascular diseases (mainly heart disease and stroke);
  • diabetes;
  • musculoskeletal disorders (especially osteoarthritis, a highly disabling degenerative disease of the joints), and
  • some types of cancer (endometrial, breast, ovarian, prostate, liver, gallbladder, kidney and colon.)

The risk of these non-communicable diseases increases as BMI increases.

Child obesity is associated with a greater chance of obesity, premature death and disability in adulthood. However, apart from these mayor future risk factors, obese children experience breathing difficulties, higher risk of fractures and high blood pressure, and early indications of cardiovascular disease, insulin resistance and psychological effects.

Facing A Double Burden Of Disease

Currently, many low-income and middle-income countries now face a ‘double burden’ of disease.

While these countries continue to deal with the problems of infectious diseases and undernutrition, they also experience an upsurge in non-communicable disease risk factors such as obesity and overweight, especially in urban settings.

It is not uncommon to find undernutrition and obesity co-existing within the same country, same community, and same household.

In low-income and middle-income countries, it is more likely that prenatal, infant and young child nutrition is inadequate. Similarly, these children are exposed to high-calorie, high-in-fat, high-in-sugar and high-in-salt foods that are also low in nutrients and tend to cost less but are also low in nutrient quality. These diet habits, along with a lack in physical activity, give rise to a sudden increase in childhood obesity while undernutrition problems remain unsolved.

How Can Overweight And Obesity Be Reduced?

Overweight and obesity, as well as linked non-communicable diseases, are mostly preventable. Supportive environments and communities are fundamental in shaping people’s choices by making the choice (the most accessible, available and affordable one) of healthier foods and regular physical activity the easiest choice, therefore preventing overweight and obesity.

At an individual level, people can choose:

  • to limit calorie intake coming from total fats and sugars;
  • to increase the intake of fruit and vegetables, as well as legumes, whole grains and nuts; and
  • to exercise regularly (30 minutes a day for young people and 150 minutes a week for adults.)

Individual responsibility can only have full effect if people have access to a healthy lifestyle. Therefore, socially, it is important to help people follow the recommendations above by continuously implementing demographic policies based on scientific evidence that make regular exercising and healthy food choices available, affordable and easily accessible to everyone, especially to the poorest individuals. An example of this type of policy is a tax on sugary drinks.

The food industry may play an important role in promoting healthy diet plans by:

  • reducing fat, sugar and salt content in processed foods;
  • ensuring that the healthy and nutritious options are available and affordable to all consumers;
  • restricting the marketing of foods high in sugar, salt and fat, especially all foods aimed at children and adolescents; and
  • ensuring healthy food options are available and supporting regular exercising in the work place.