Overweight and Obesity

The information here is provided by courtesy of the Network's short online course - "An Introduction to Global Health". 




The problem


Overweight and obesity are major contributors to deaths from Non-Communicable Diseases, being linked to cardiovascular disease, musculoskeletal disorders and some cancers. 




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 their height in metres (kg/m2).


For adults, WHO defines overweight and obesity as follows:


  • Overweight : Overweight is a BMI greater than or equal to 25
  • Obesity : Obesity is a BMI greater than or equal to 30.


For children under 5 years of age:


  • Overweight : Overweight is weight-for-height greater than 2 standard deviations above WHO Child Growth Standards median
  • Obesity : Obesity is weight-for-height greater than 3 standard deviations above the WHO Child Growth Standards median




Overweight and obesity are now linked to more deaths worldwide than underweight.

Globally there are more people who are obese than underweight. This applies in all regions of the world with the exceptions of sub-Saharan Africa and Southern Asia. (Map 1) 


Map 1





Features of obesity in the world


  • Worldwide obesity has nearly tripled since 1975.
  • In children and adolescents aged 5 - 19 years, overweight and obesity has risen from 4% in 1975 to just over 18% in 2016. 
  • In 2016 more than 1.9 billion (39%) adults (18 years and older) were overweight. Of these over 650 million (13%) were obese.
  • 38 million children in the world under 5 years were overweight or obese.




Overweight and obesity have arisen because globally there has been


  • An increased intake of energy-dense foods that are high in fat and sugars
  • A decrease in physical activity due the increasingly sedentary forms of work, changed modes of transportation and increased urbanisation.
  • Obesity and overweight are preventable.




a) Individuals 


At the individual level, people can:


  • limit energy intake from total fats and sugars;
  • increase consumption of fruit and vegetables, as well as legumes, whole grains and nuts
  • engage in regular physical activity (60 minutes a day for children and 150 minutes spread through the week for adults).


b) Society 


The environment has become obesogenic (it is conducive to becoming overweight and obese) and strategies are needed both to change the environment and promote lifestyle change.


At the societal level it is important to support individuals in following the recommendations above, through sustained implementation of evidence based and population based policies that make regular physical activity and healthier dietary choices available, affordable and easily accessible to everyone, particularly to the poorest individuals. An example of such a policy is a tax on sugar sweetened beverages. 



Further Reading 


 WHO : Global strategy on diet, physical activity and health – 2004



Tenfold increase in childhood and adolescent obesity in four decades: new study by Imperial College London and WHO



WHO : Fact Sheet on a Healthy Diet



WHO : More on obesity



WHO : Global Health Observatory on body mass index 



WHO : Nutrition and various activities co-ordinated by WHO





Overweight and Obesity image