About Obesity

Obesity: Definition and Global Impact

Obesity is a chronic medical condition characterized by excessive body fat accumulation that impairs health. It is typically measured using Body Mass Index (BMI), where a BMI of 30 or higher indicates obesity. This condition develops when caloric intake consistently exceeds energy expenditure, leading to abnormal fat storage.


Epidemiology of Obesity

Obesity has reached epidemic proportions globally, with developed nations particularly affected. In countries like Australia, obesity rates have risen dramatically in recent decades. This upward trend is concerning because obesity significantly increases the risk of numerous health complications, including cardiovascular diseases, type 2 diabetes, and certain cancers, while also contributing to premature mortality.

How Does Obesity Affect You?

Obesity substantially contributes to
  • preventable, non-communicable diseases, 
  • shortened life-expectancy and
  • impaired quality of life.
Obesity is a major risk factor for chronic conditions such as 
  • Type 2 Diabetes, 
  • Heart disease, 
  • Hypertension, 
  • Stroke, 
  • Musculoskeletal disorders and 
  • Impaired psychosocial functioning.
Obesity is now challenging smoking as the major cause of potentially preventable death in Australia.

Changing Perceptions

Before

In the past, obesity was seen as a weakness or failure of the individual. Diet and exercise were prescribed treatments and weight loss surgery viewed as dangerous and extreme.

Today

Now, obesity is considered a disease and the cause of many serious health conditions. Obesity is no longer considered a cosmetic issue due to eating too much. The World Health Organisation (W.H.O) from 2013 recognizes obesity as a chronic progressive disease resulting from multiple environmental and genetic factors.

Weight Loss Surgery has gained acceptance as a proven method to treat this disease. But surgical treatment is not for all obese patients.

What are the Causes of Obesity?

Weight gain and long-term obesity can be caused by a number of factors:
  • Genetics
  • Lack of exercise
  • Overeating
  • Poor diet

Symptoms of Obesity

Clinical obesity and weight gain can have a negative impact on your physical and mental health. Some symptoms or side effects of obesity include:
  • Low back pain or Backaches.
  • Feeling tired all the time.
  • Heavy sweating.
  • Joint pain (especially weight-bearing knee and hip joints).
  • Low confidence or self-esteem.
  • Shortness of breath.
  • Snoring or Sleep Apnoea.

Obesity Diagnosis

The Body Mass Index (BMI) is the most commonly used method for determining a patient’s weight category. The BMI is calculated by measuring the height and weight of the patient.

Other methods for diagnoses include:
  • Blood tests.
  • Physical exam.
  • Review of family history.
  • Waist measurement.
A GP may ask additional questions about your lifestyle and any potential underlying health issues.

Classification of Obesity

Morbid obesity, also referred to as “clinically severe obesity” or “extreme obesity,” was defined as the criteria for bariatric surgery by the 1991 NIH Consensus Conference Statement on Gastrointestinal Surgery for Severe Obesity as a BMI ≥ 40 kg/m^2^ or a BMI ≥ 35 kg/m^2^ in the presence of high-risk comorbid conditions.

Obesity was further classified in the 1998 NIH Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults into Class I, Class II, and Class III.
Category BMI Range
Normal Size 18.9 to 24.9
Overweight 25 to 29.9
Class I, Obesity 30 to 34.9
Class II, Serious Obesity 35 to 39.9
Class III, Severe Obesity 40 and greater

Why Treat Obesity?

If left untreated, obesity can lead to a number of serious health issues including:
  • Arthritis
  • Certain cancers
  • Coronary heart disease
  • High blood pressure
  • Psychological conditions
  • Respiratory disorders
  • Sleep apnea
  • Stroke
  • Type two diabetes

Obesity Treatments

Several strategies are available to manage and treat obesity, including:

  • Dietary 
  • Exercise
  • Medication
  • Behavioral interventions


While these methods may lead to modest weight loss and health improvements, their long-term effectiveness is often limited, particularly in individuals with severe or long-standing obesity (Apovian et al., 2015; Wadden et al., 2012).


For those affected by obesity bariatric surgery has been shown to be the most effective and durable treatment option. It not only leads to significant and sustained weight loss but also improves or resolves many obesity-related comorbidities such as type 2 diabetes, hypertension, and obstructive sleep apnea (Schauer et al., 2017; Arterburn et al., 2020). As such, bariatric surgery is considered the gold standard for long-term obesity management in appropriate candidates.