What is Obesity?

The World Health Organisation (March 2024) defines obesity as a chronic complex disease defined by excessive "fat" deposits (adipose cells) that can impair health.

The adipose "fat" cells the body naturally has start to increase in size; then over time also multiply in number and start to be deposited in areas where they shouldn't eg in the liver, on/ around the heart, and other vital organs. These adipose cells activate inflammation throughout the body which disrupts mitochondria. The mitochondria are the powerhouse of all cells in the body; when they are dysfunctional, it results in damage to cells and body organs and so these also become dysfunctional.

It may take years before the person living with obesity starts to experience symptoms; however the impairment to the body in general, has been occurring for years.

It can interfere with basic physical functions such as breathing, walking and self-care in some instances. Long-term implications of obesity-caused inflammation-induced impairment include: shorter life expectancy, serious health consequences in the form of health complications, reduced quality of life, reduced mental wellbeing and sometimes fewer economic and/or social opportunities etc.

There is the recognition that not every individual who fulfills the current criteria for living with obesity will have a “disease” at any single point in time. As a result, the Lancet Commission is currently working on defining "clinical obesity" and hopes to report their conclusions in late 2024.

It is understood that such apparently “healthy individuals with obesity” will likely develop metabolic risk factors and physical dysfunction with age, whilst they are still living with obesity.

The causes of obesity are many and complex, and may include a combination of the following:

The genes you inherited from your parents
The way your genes interact with the environment and are expressed (epigenetics)
Your metabolism ie how well your body turns food into energy, which is then used to keep you alive
Your nutritional intake (eating habits)
Changes in the bacteria and cells which live in your gut (gut microbiome)
Your physical activity levels (including incidental and structured exercise)
Your environment including your surroundings/where you live, sleep patterns, stress levels, work shift patterns etc
Medical conditions and/or medications used to treat these conditions
Psychological factors-which may influence your environment but also may influence your relationship with food.

Obesity affects individuals, their families and/ or carers and the wider community.

Given its progressive nature, lifelong management will be required.

Glossary of terms:

The term “disease process” recognizes that the risk factors for associated disease may not be present in every individual who meets the criteria for obesity but that excessive adiposity ultimately leads to health consequences in the vast majority people.
The term “chronic” bears difference to the fact that obesity is persistent and the physiological changes and consequent ill health develop over time.
The term “relapsing” refers to the difficulty in achieving lasting reduction in weight despite successful episodes where weight and fat stores have been reduced.
Thus, chronic relapsing disease process can be seen as an accurate and representative description of the development and progression of obesity.
Inherent in the description of a disease of a “disease process” is the recognition that not every individual who fulfils the current criteria for obesity will have a “disease” at any single point in time. It is understood however that such “healthy” individuals with obesity will likely develop metabolic risk factors and physical dysfunction with age whilst they continue to live with obesity.

Adapted from the following reference:

Bray G, Kim KK, Wildling J. Obesity: a chronic relapsing progressive disease process. A position statement of the World Obesity Federation. Obesity Reviews 2017; 18 715 – 723.