Obesity has reached crisis levels in Australia, with 67% of Australians classified as being overweight or obese (2022 data). BMI measurements have been used in epidemiological studies to define overweight individuals with a measurement of 25 kilograms per metre squared and obese individuals with a BMI measurement of more than 30 kilograms per metre squared. It is now recognised, however, that BMI-based measures of obesity may both underestimate or overestimate adiposity and provide inadequate information about health at the individual level and subsequently undermine medically sound approaches to healthcare and policy. A recent Commission of 58 experts in this field reported a consensus in The Lancet defining obesity as "a condition characterised by excess adiposity, with or without abnormal distribution or function of adipose tissue and with causes that are multifactorial and still incompletely understood". They subsequently teased out the diagnosis of obesity to include preclinical and clinical definitions, where:

Pre-clinical obesity is defined by excess fat accumulation as measured by direct means with DEXA or indirect anthropometric measurements such as waist to height, waist circumference or waist to hip ratio measurement. This group of patients have no clinical disease or end-organ damage or symptoms as yet, but an increased risk of developing clinical obesity and conditions such as type 2 diabetes, cardiovascular disease and some neoplasms. The treatment focus in this group includes counselling and the introduction of measures to prevent progression to the next subgroup, which is clinical obesity.

Clinical Obesity is defined as a chronic, systemic illness characterised by alterations in the function of tissues, organs, the entire individual, or a combination thereof, due to excess adiposity. Clinical obesity can lead to severe end-organ damage, causing life-altering and potentially life-threatening complications. The main focus of management for this cohort is to improve end-organ dysfunction as a priority rather than to focus on weight loss alone. Treatment options include lifestyle modification through diet and counselling, and rely on established pharmacology such as GLP-1 receptor agonists, which are likely to be used as a long-term treatment strategy. For a select number of patients, however, these medications can induce nausea, vomiting, diarrhoea, constipation and reflux. In more serious cases gastro paresis and pancreatitis are described. Non-responsiveness and high cost may be a limiting factor amongst some patients. Consequently, surgery remains the cornerstone for safely and effectively managing obesity and includes both gastric sleeve and bypass operations.

To discuss this new definition of obesity and approach to thinking about obesity, as well as to review surgical options, I was curious to open a discussion with Dr Melissa Beitner. Melissa is a fellow of The Royal Australasian College of Surgeons; she is American Board of Surgery certified, a fellow of the American Society of Metabolic and Bariatric Surgery and is a diplomat of the American Board of Obesity Medicine. Melissa is incredibly well credentialed, having undertaken bariatric surgery fellowships at Mount Sinai Hospital in New York, Royal Brisbane and Women's Hospital and St. George Hospital, Sydney. She has special areas of interest in bariatric surgery and obesity medicine, and is also highly skilled in hiatus hernia and anti-reflux surgery, cholecystectomy and general surgical removal of lumps and bumps. Please welcome Meissa to the podcast.

References: 

Dr Beitner, Weight Loss Solutions: www.360surgery.com.au

Definition and Diagnostic Criteria of Clinical Obesity, F Rubino et al. The Lancet Diabetes and Endocrinology Commission. Vol 13, Issue 3, P221-262, March 2025