Samuel's BMI is 40

What is obesity?

Obesity is a complex and multifactorial disease that is influenced by physiological, psychological, environmental, socio-economic and genetic factors.¹ ²

Click on each factor above to find out more.

Is obesity a disease?

European Association for the Study of Obesity (EASO)

“A progressive disease, impacting severely on individuals and society alike, it is widely acknowledged that obesity is the gateway to many other disease areas.”12

The Obesity Society (TOS)

It is the official position of The Obesity Society that obesity should be declared a disease.8

American Medical Association (AMA)

"Recognizing obesity as a disease will help change the way medical community tackles this complex issue that affects approximately one in three Americans."9

American Association of Clinical Endocrinologists (AACE)

"...obesity is a primary disease, and the full force of our medical knowledge should be brought to bear on the prevention and treatment of obesity as a primary disease entitity."10

World Obesity Federation (WOF)


The World Obesity Federation takes the position that obesity is a chronic, relapsing, progressive disease process and emphasises the need for intermediate action and the prevention and control of this global epidemic.11


Acknowledgement of obesity as a disease could improve the overall management of obesity.14

How have global obesity trends changed?

The global prevalence of obesity has nearly tripled since 1975. In 2016, more than 1.9 billion adults aged ≥18 were overweight. Of these, 13% had obesity.15


  • Female
  • Male
prevalence of obesity among women, >18, 2016

What complications are linked to obesity?

Obesity is associated with more than 195 complications.18


Click on each of the obesity-related complications below to find out more.  

The global economic impact of treating obesity and its related complications amounts to $800 billion per year and it is expected to reach $1.2 trillion by 2025.24


The cost of obesity is comparable to other non-communicable diseases, such as cardiovascular disease for which the global cost will reach $1 trillion by 2030.25

What are the benefits of a weight loss of 5% or more?

the benefits of a weight lost of more than 5%

Why is it hard to lose weight and keep it off?

Physiological responses to weight loss favour weight regain.4,39-42

Weight loss alters the body's homeostatic system,43 which controls appetite, energy intake and energy expenditure,44 causing the body to increase hunger and lower the metabolic rate.43

Want to learn more about the science behind obesity? View our obesity mode of disease video. 

metabolic adaptations to weight loss

Weight loss in people with obesity causes changes in appetite hormones that increase hunger and the desire to eat for at least 1 year.4



How can obesity be treated?

Obesity should be treated holistically and as a serious chronic disease.10,47

Evidence-based lifestyle therapy for obesity should include diet, exercise and behavioural modification.47 Healthy eating, physical activity and behaviour therapy should be first-line interventions in all individuals with a BMI ≥25 kg/m2  and they must be part of any weight-loss intervention.47 However, these interventions are not always sufficient to maintain weight loss.45,48


Pharmacotherapy for obesity can be considered if lifestyle therapy does not provide sufficient clinical benefit for individuals with a BMI of ≥30 kg/m2, or ≥27 kg/m2 with obesity-related complications.48 Anti-obesity medications can act directly on the central nervous system, inducing weight loss by reducing appetite, or act peripherally and induce weight loss by interfering with absorption from the gastrointestinal tract.49


Bariatric procedures are the third-line intervention for obesity management, which is recommended in individuals with a BMI ≥40 kg/m2, or ≥35 kg/m2 with comorbidities. Bariatric surgery can be malabsorptive or restrictive, with each type requiring different lifestyle changes.50

Click here to explore our patient interaction tools to aid initiation or follow-up of dialogue with patients about their obesity management.

Science behind obesity additional materials

Explore the science behind obesity interactive infographic to learn more about the factors inside and outside the body that affect a person’s likelihood of developing obesity.