Topic 1 Definition of obesity

Overweight and obesity are defined by the World Health Organization (WHO) as “abnormal or excessive fat accumulation that presents a risk to health”.
For adults a body mass index (BMI) over 25 is considered overweight, while over 30 is obese.
For children, age needs to be considered when defining overweight and obesity.

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

Overweight is BMI-for-age greater than 1 standard deviation above the WHO Growth Reference median
Obesity is BMI-for-age greater than 2 standard deviations above the WHO Growth Reference median.

Rates of overweight and obesity continue to grow in adults and children.
From 1975 to 2016, the prevalence of overweight or obese children and adolescents aged 5–19 years has increased more than four-fold from 4% to 18% globally.
Obesity is one side of the double burden of malnutrition and today more people are obese than underweight in every region except sub-Saharan Africa and Asia.
Once considered a problem only in high-income countries, overweight and obesity are now dramatically on the rise in low- and middle-income countries, particularly in urban settings.
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.

Multiple factors has led to unhealthy eating habits and the consequent increase in childhood obesity: