Understanding obesity

What is obesity?

Obesity has been widely recognised as one of the greatest health challenges of the 21st century, although not easy to define and label.

As a chronic disease, obesity requires long-term management. In medical terms, it is defined as excess fat storage, leading to impaired health. As such, healthcare professionals would usually use Body Mass Index (BMI) to find out whether or not an individual has overweight or obesity. 

Typically, a BMI of 30 kg/m2 or greater is classified as obesity, and a BMI of over 25 kg/m2 is considered overweight.

Causes of obesity

Obesity itself is ultimately caused by long-term energy imbalance, created when an individual’s calories consumption is greater than the amount their body uses. This in turn leads to the excess energy being stored as fat.

Although driven by weight gain, obesity is also known to be a complex and multifactorial disease that is influenced by a variety of factors, including:

  • Psychological factors (e.g. relating to emotional regulation and wellbeing)
  • Physiological factors (e.g. relating to individual biology)
  • Environmental factors (e.g. relating to social eating habits)
  • Genetic factors (e.g. relating to genes that affect metabolism)


The reason obesity is seen as a major health concern, is that having overweight or obesity can lead to the development of other dangerous medical conditions, including: Type 2 diabetes, high blood pressure, obstructive sleep apnoea (sleep-related breathing disorder) and certain types of cancer. In addition, research has shown that the effect of obesity-related stigma on some people can lower quality of life.

However, research has also shown that even a modest weight loss of 5%-10% body weight can significantly improve your health. If you are living with overweight or obesity, speak to your healthcare professional to evaluate your overall health and steps you can take to improve your health and maintain weight loss over time.