Obesity as defined by WHO guidelines:
Obesity is a complex, chronic disease characterized by the substantial accumulation of body fat that can negatively impact health. According to the World Health Organization (WHO), obesity is generally defined and classified using the Body Mass Index (BMI), a simple measure calculated as weight (in kilograms) divided by height squared (in meters squared, kg/m²).
WHO BMI classifications:
- Overweight: BMI of 25 or more
- Obesity Class I (Moderate obesity): BMI of 30-34.9
- Obesity Class II (Severe obesity): BMI of 35-39.9
- Obesity Class III (Morbid or extreme obesity): BMI of 40 or more
Key points from WHO guidelines:
- Evidence-based approach: WHO guidelines are developed using the GRADE methodology to assess the quality and certainty of evidence and the strength of recommendations.
- Health risks: The BMI thresholds are established based on associations with certain morbidities and excess mortality. Obesity is linked to serious health conditions like cardiovascular diseases, diabetes, and certain cancers.
- Global prevalence: In 2019, WHO estimated that 38 million children under 5 were overweight or obese, and in 2016, 340 million children and adolescents aged 5–19 were overweight or obese.
- Future considerations: WHO is focusing on defining risk stratification by obesity severity and considering health system constraints for treatment access.
Important note: While BMI is a useful screening tool, it may not directly measure body fat. Alternative assessments may be needed for some individuals, such as those with high muscle mass (RAG results).
For the most up-to-date information, you can refer to the WHO's official guidelines on obesity, which are periodically reviewed and updated.
Sources:
- WHO guideline development process (RAG results)
- WHO BMI classifications (RAG results and Wikipedia)
- WHO global obesity prevalence (RAG results)