Systemic inflammatory mechanisms through which obesity contributes to disease

To effectively understand the link between obesity and chronic disease, as well as why losing weight is beneficial, it helps to understand the mechanisms at play. One of the most important things to understand is that adipose (fat) tissue is an active paracrine and endocrine organ. This means that fat tissue secretes hormones and bioactive compounds, crucially including inflammatory markers, both to surrounding tissues, and directly into the bloodstream from which they are transported throughout the body. Adipose tissue is mainly made up of adipocytes (fat cells). It is the adipocytes which store energy and are responsible for endocrine activity. Adipose is vascularized tissue and so also includes vascular cells, as well as immune cells which regulate the immune response of the adipose tissue and fibroblast cells which provide structural and mechanical support.

Having an obesity phenotype with increased adipose tissue causes a down regulation of anti-inflammatory markers (including adiponectin), as well as an upregulation in pro-inflammatory markers known as adipokines which include leptin, resistin, tumour necrosis factor, interleukin-6 and others. It is the upregulation of these adipokines which leads to the development of a chronic inflammatory state, and this is the driver of ‘metabolic syndrome’. Metabolic syndrome is a term used to describe the presence of multiple comorbidities including dyslipidemia, insulin resistance, hyperglycemia and hypertension. Obesity promotes systemic metabolic dysfunction, and in turn this affects multiple organ systems throughout the body.

Key point: When excess adipose tissue is present, this causes an upregulation in the volume of certain hormones and inflammatory markers in the body. Obesity is therefore a metabolically active inflammatory state. Secretion of increased amounts of these inflammatory markers is a systemic mechanism which contributes to disease states affecting many different physiological processes in the body.