Managing obesity is challenging and new treatment involves multimodal long-term care tailored to each patient. Dietary and lifestyle management are cornerstone to all treatment options, and pharmacotherapy has an adjuvant role in aiding appetite suppression. In people with morbid obesity and those with obesity and comorbidities, durable weight loss can be safely achieved with bariatric surgery. There are several surgical options, with current evidence favouring sleeve gastrectomy.
Obesity: a rising burden of disease in current times
Obesity, defined as abnormal or excessive fat accumulation that may impair health, is a polymorphic chronic disease that has increased in both incidence and prevalence throughout the 20th and 21st centuries.1 It has reached epidemic proportions and is now one of the most important public health issues globally.2 During the COVID-19 pandemic, it also appears that people with obesity have been disproportionately affected.3 The risk of coronavirus-related hospital death increases 1.5 to two times for people with a body mass index (BMI) of 30 kg/m2 to more than two times for those with a BMI of 40 kg/m2 or more.
The most commonly used criterion for obesity is a BMI of 30 kg/m2 or more. However, BMI should be used as a crude measurement, keeping in mind that certain groups in the Australian population, such as people of South Asian descent, are prone to the complications of obesity at lower BMIs.4
Body weight and fat mass are highly heritable traits, with important genetic and epigenetic aetiological factors.5 The rise in the prevalence of obesity has largely been driven by environmental factors including an abundance of calorie-rich food and a lack of physical activity.6 Based on World Health Organization data, an estimated 650 million adults worldwide were obese in 2016 and 2.1 billion were overweight.7 It is predicted that without significant action approximately 223 million children will have excess weight by 2025.7,8
The incidence of comorbidities that have obesity as a strong contributory factor and are responsible for a large public health burden have risen along with those of obesity. These comorbidities include type 2 diabetes, cardiovascular disease (e.g. coronary heart disease, cerebrovascular disease), musculoskeletal disorders (e.g. osteoarthritis) and cancers with an aetiological association with obesity (e.g. oesophageal adenocarcinoma and some breast, ovarian, prostate, liver, colon and renal cancers).9
The challenge of treating obesity requires a commitment from the patient to lifelong permanent changes in eating and activity behaviours. Achieving this involves combinations of low-calorie diets, exercise programs, pharmacotherapy and, in some patients, bariatric surgery.
Doctors should be familiar with the basic principles of pharmacotherapy for obesity. For more than 20 years, the US National Institutes of Health has recommended that individuals who fail to respond to lifestyle interventions after six months of treatment, and have a BMI of 30 kg/m2 or more, or a BMI of 27 kg/m2 or more with weight-associated comorbidities, may be considered for weight loss medication treatment.10
Pharmacotherapy has an adjuvant role to diet and exercise and may be helpful to ‘kick start’ weight loss and aid appetite suppression. Pharmacotherapy adjuncts for weight loss date back to the 1920s, and agents such as phentermine have been used since the 1950s.11 Newer formulations offer greater flexibility of dosing and there are now new combinations of drugs, some of which have recently been made available in Australia.