About Obesity

This section contains an overview on some of the key topics in obesity. All information was sourced from the World Health Organisation.

What are overweight and obesity?

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

Body mass index (BMI) is a simple index of weight-for-height that is commonly used to classify overweight and obesity in adults. It is defined as a person’s weight in kilograms divided by the square of his height in meters (kg/m2).

The WHO definition is:

  • A BMI greater than or equal to 25 is overweight
  • A BMI greater than or equal to 30 is obesity

BMI provides the most useful population-level measure of overweight and obesity as it is the same for both sexes and for all ages of adults. However, it should be considered a rough guide because it may not correspond to the same degree of fatness in different individuals.

Source: World Health Organisation Fact sheet N°311

What causes obesity and overweight?

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

  • An increased intake of energy-dense foods that are high in fat; and
  • An increase in physical inactivity due to the increasingly sedentary nature of many forms of work, changing modes of transportation, and increasing urbanization

Changes in dietary and physical activity patterns are often the result of environmental and societal changes associated with development and lack of supportive policies in sectors such as health, agriculture, transport, urban planning, environment, food processing, distribution, marketing and education.

Source: World Health Organisation Fact sheet N°311

Health consequences of overweight and obesity

Raised BMI is a major risk factor for noncommunicable diseases such as:

  • Cardiovascular diseases (mainly heart disease and stroke), which were the leading cause of death in 2012;
  • Diabetes;
  • Musculoskeletal disorders (especially osteoarthritis – a highly disabling degenerative disease of the joints);
  • Some cancers (endometrial, breast, and colon)

The risk for these noncommunicable diseases increases, with an increase in BMI.

Childhood obesity is associated with a higher chance of obesity, premature death and disability in adulthood. But in addition to increased future risks, obese children experience breathing difficulties, increased risk of fractures, hypertension, early markers of cardiovascular disease, insulin resistance and psychological effects.

Source: World Health Organisation Fact sheet N°311

Childhood obesity trends

Childhood obesity is one of the most serious public health challenges of the 21st century.

Overweight and obese children are likely to stay obese into adulthood and more likely to develop noncommunicable diseases like diabetes and cardiovascular diseases at a younger age.

  • In 2013, 42 million children under the age of 5 were overweight or obese
  • The vast majority of overweight or obese children live in developing countries, where the rate of increase has been more than 30% higher than that of developed countries
  • If current trends continue the number of overweight or obese infants and young children globally will increase to 70 million by 2025
  • Obesity in childhood is associated with a wide range of serious health complications and an increased risk of premature onset of illnesses, including diabetes and heart disease
  • Without intervention, obese infants and young children will likely continue to be obese during childhood, adolescence and adulthood

Every aspect of the environment in which children are conceived, born and raised can contribute to their risk of becoming overweight or obese. During pregnancy, gestational diabetes (a form of diabetes occurring during pregnancy) may result in increased birth weight and risk of obesity later in life.

Sources:

World Health Organisation Fact sheet N°311

World Health Organisation, Facts and figures on childhood obesity

Global obesity trends and prevalence facts

Recent WHO global estimates indicate:

  • In 2014, more than 1.9 billion adults, 18 years and older, were overweight. Of these over 600 million were obese
  • Overall, about 13% of the world’s adult population (11% of men and 15% of women) were obese in 2014
  • In 2014, 39% of adults aged 18 years and over (38% of men and 40% of women) were overweight
  • The worldwide prevalence of obesity more than doubled between 1980 and 2014

“Double burden” of disease:

Once considered a high-income country problem, overweight and obesity are now on the rise in low- and middle-income countries, particularly in urban settings.

  • While they continue to deal with the problems of infectious disease and under-nutrition, they are experiencing a rapid upsurge in noncommunicable disease risk factors such as obesity and overweight, particularly in urban settings
  • It is not uncommon to find under-nutrition and obesity existing side-by-side within the same country, the same community and the same household

Overweight and obesity are linked to more deaths worldwide than underweight. Most of the world’s population live in countries where overweight and obesity kill more people than underweight (this includes all high-income and most middle-income countries).

Source: World Health Organisation Fact sheet N°311