Is obesity a disease?

A Fact Check special

Introduction

The impact of obesity on health is causing increasing concern in Australia.

More than one in four adults are obese, compared to one in 10 in 1989. Since the mid-1990s men are on average 3.6 kilos heavier, women are four kilos heavier, and by one estimate obesity is costing the nation $60 billion a year.

Associate Professor John Dixon, from the Baker IDI Heart & Diabetes Institute in Melbourne, wants the Federal Government and the Australian Medical Association to label obesity a disease.

He's part of a growing chorus of medical experts calling on governments to offer obese people more treatment options, including greater access to weight-loss surgery, drugs and diet plans.

"We are treating a chronic disease," Associate Professor Dixon told ABC RN's Health Report. "If we've got effective tools to treat a deadly and disabling disease, we should use them."

Being overweight or obese is already linked to a range of diseases including type two diabetes, heart disease and a number of cancers. But is obesity itself a disease?

ABC Fact Check investigates.

Defining obesity and disease

Obesity

The Macquarie Dictionary defines obesity as "a medical condition in which excess body fat affects the health of the individual, often leading to heart disease and diabetes".

Calculate your BMI BMI

For example, an adult who weighs 60 kilograms and is 1.7 metres tall would calculate their BMI by doing the following: 60 divided by 2.89 (1.7 x 1.7).

That person would have a BMI of 20 and a classification of normal. What's your BMI? If you have a BMI less than 18.5 your classification is underweight and your risk of co-morbidities is low

your classification is and your risk of co-morbidities is If you have a BMI between 18.5 and 24.99 your classification is normal and your risk of co-morbidities is average

your classification is and your risk of co-morbidities is If you have a BMI greater than 25 your classification is overweight

your classification is If you have a BMI between 25 and 29.99 your classification is pre-obese and your risk of co-morbidities is increase

your classification is and your risk of co-morbidities is If you have a BMI between 30 and 34.99 your classification obese class 1 and your risk of co-morbidities is moderate

your classification and your risk of co-morbidities is If you have a BMI between 35 and 39.99 your classification is obese class 2 and your risk of co-morbidities is severe

your classification is and your risk of co-morbidities is If you have a BMI greater than 40 your classification is obese class 3 and your risk of co-morbidities is very severe BMI is calculated by dividing your weight in kilograms by your height in metres squared.For example, an adult who weighs 60 kilograms and is 1.7 metres tall would calculate their BMI by doing the following: 60 divided by 2.89 (1.7 x 1.7).That person would have a BMI of 20 and a classification of normal. What's your BMI?

The Australian Government defines obesity according to body mass index, which is calculated by dividing weight in kilograms by height in metres squared. It says obesity is a BMI of greater than 30.

Disease

The Macquarie Dictionary defines disease to be "a morbid condition of the body, or of some organ or part; illness; sickness; ailment".

The American Medical Association says disease "lacks a single, clear, authoritative, and widely-accepted definition".

In an article published in Nature magazine in 2001, New York researchers Stanley Heshka and David Allison examined the characteristics of obesity to determine "whether they fit the common and recurring elements of definitions of disease taken from a sample of authoritative English language dictionaries".

They concluded: "Obesity, defined as a body mass index... or percentage body fat in excess of some cut-off value, though clearly a threat to health and longevity, lacks a universal concomitant group of symptoms or signs and the impairment of function which characterise disease according to traditional definitions."

Obesity is officially classified as a disease under the World Health Organisation's International Classification of Diseases.

In a report published in 2000, the WHO said: "Obesity is a chronic disease, prevalent in both developed and developing countries, and affecting children as well as adults. Indeed it is now so common that that it is replacing the more traditional public health concerns, including under-nutrition and infectious disease, as one of the most significant contributors to ill health."

Australia: Not classified as a disease

It is widely recognised that the effects of overweight and obesity are one of Australia's leading health concerns. Department of Health

The Australian Government stops short of labelling obesity a disease.

"The Australian Government recognises that being overweight or obese is strongly associated with several chronic diseases including type 2 diabetes, cardiovascular disease and some cancers, and with mental health and eating disorders," a spokeswoman for the Department of Health told Fact Check.

"It is widely recognised that the effects of overweight and obesity are one of Australia's leading health concerns."

In 2009 an inquiry by a federal parliamentary committee recommended labelling obesity a chronic disease and requiring GPs to provide individual management plans.

In its 2013 response the government says although it does not recognise obesity as a chronic disease "there are circumstances in which a patient with obesity could be eligible for [Medicare] items such as when a patient has complications of co-morbidities that may be a result of, or exacerbated by, obesity".

The Australian Medical Association has also shied away from labelling it a disease.

The association says classifying obesity as a disease would have significant costs. "The Government determines which diseases are classified, and cost to Medicare is a significant determining factor," an AMA spokeswoman said.

The spokeswoman says the Australian Medical Association has "no position" on whether the Government classifies obesity a disease.

She says if obesity was labelled a chronic disease it would cost the Government $700 million for GPs to draw up chronic health plans for obese Australians.

In addition to the $700 million, "Medicare would have to fund allied health services required by the plan," she said.

But Professor John Funder, the chair of Obesity Australia, an organisation which seeks to change public perceptions, argues medicalising obesity would empower general practitioners to better manage their obese patients.

The US: Classified as a disease

In June 2013 the American Medical Association classified obesity as a disease requiring a range of medical interventions and prevention.

"Recognising obesity as a disease will help change the way the medical community tackles this complex issue that affects approximately one in three Americans," AMA board member Dr Patrice Harris said.

"The suggestion that obesity is not a disease but rather a consequence of a chosen lifestyle exemplified by overeating and/or inactivity is equivalent to suggesting that lung cancer is not a disease because it was brought about by individual choice to smoke cigarettes," the association noted.

But recognising obesity as a disease has not always been the American Medical Association's position. The association's Council on Scientific Affairs previously ruled against it, arguing "it was premature to classify obesity as a disease, citing the lack of characteristic signs or symptoms due to obesity, as well as evidence of any true causal relationships between obesity and morbidity and/or mortality".

Boyd Swinburn, a professor of population nutrition and global health at the University of Auckland, tells Fact Check that using BMI to define a disease does not allow a clear-cut point for making a diagnosis.

He says BMI is a continuous variable - which changes with people's weight - and is like other continuous risk factors such as blood pressure and blood cholesterol.

"Calling obesity a disease also medicalises the condition and it would mean that a large minority of the population would now have this disease," Professor Swinburn said.

A 2014 study by the University of Minnesota examined the impact of the American Medical Association's decision to classify obesity a disease and found it "weakened the importance placed on health-focused dieting and reduced concerns about weight among obese individuals - the very people whom such public-health messages are targeting". It also found that it lowered body-image dissatisfaction.

The gene factor

The theme is set before the kid can reach the fridge door. Professor John Funder

One of the main arguments experts give for wanting to classify obesity as a disease is that genes play a key role.

It's often argued that lifestyle choices, including overeating high calorie food and a lack of exercise, are the main contributing factors to obesity, but some experts are keen to push back at the prevailing view of obesity as a "disease of sloth".

Professor Lesley Campbell from the Garvan Institute of Medical Research in Sydney tells Fact Check there is good evidence that between 40 and 70 per cent of a person's weight is inherited.

"I want to let people understand the science is that obesity has high heritability and is not a 'choice' or 'weak will'," she said.

Overeating studies have shown there is as much as a fourfold difference in the amount of weight a person will gain if fed the same high calorie diet, Professor Michael Cowley, a physiologist who works at Monash University in drug development for obesity and diabetes, tells Fact Check.

One study by Canadian scientist Claude Bouchard took young adult identical twins, put them on a high calorie diet and found there was "significant" similarity within each pair of twins in response to overfeeding, with respect to body weight, percentage of fat, fat mass and estimated subcutaneous fat. There was about three times more variance in these measures among the sets of twins involved in the study than within the sets of twins.

The study concluded that genetic factors "may govern the tendency to store energy as either fat or lean tissue and the various determinants of the resting expenditure of energy".

"The theme is set before the kid can reach the fridge door," Professor Funder said.

Programmed from birth

But does our evolving understanding of the role genes play in a person's likelihood to gain weight account for burgeoning obesity?

Professor Funder says genes themselves have not radically changed over the past 50 years. However, he says the way our genes are being programmed, or the 'epigenetics', is changing.

Epigenetics are best explained as the "stop" and "go" signals that are sent to our genes.

Professor Funder says there is a lot of evidence to show that the eating patterns of pregnant women are programming the genes of the fetus. If a mother is obese, this predisposes the unborn child to also become obese.

The World Obesity Federation, which represents members of the scientific, medical and research communities, says "increasing numbers of overweight young women are now having children who are large at birth and much more prone to future obesity".

"So we have a looming generational amplification of the already huge public health burden," it said.

Epigenetics could in part account for the growing numbers of obese children. Around the world, more than 40 million children under the age of five were overweight or obese in 2012.

Health consequences

One third of people who are obese don't have metabolic problems, and it doesn't necessarily make you sick. Professor Lesley Campbell

Professor Campbell says that "obesity does not always appear to cause medical consequences". She says in up to 30 per cent of people, obesity itself isn't a disease.

A 2012 study done by scientists at Sydney's St Vincent's Hospital notes that in most people, obesity and insulin resistance coexist. Insulin resistant people are more likely to be obese.

However, the study showed that was not always the case. "A unique group of obese individuals... exhibited better insulin sensitivity than expected" for their body fat levels, it said.

Professor Campbell, who worked on the study, tells Fact Check that "one third of people who are obese don't have metabolic problems, and it doesn't necessarily make you sick".

She says by calling it a disease "we actually burden the ones that, as far as we know, are fat by our definitions, but have no obvious consequence, and we shouldn't necessarily medicalise them".

The study is now calling the participants back in for a five-year review. Professor Campbell warns that the protection from metabolic problems may not be "a lifelong thing".

Professor Funder says that for people over the age of 65, being overweight or obese doesn't necessarily have negative health outcomes. He says a person's health condition is largely dictated by their level of physical activity.

Environmental factors

Professor Campbell says the role of the "obesogenic environment" is also a major contributing factor in the obesity epidemic.

The obesogenic environment refers to an environment that helps, or contributes to, obesity. "Modifying the obesogenic environment... could include access to healthy food and access to places to be physically active; thereby, supporting an individual’s healthy behaviours," researchers at the University of Nevada said.

Professor Campbell argues obesity is like alcoholism in the sense that in an environment where alcohol is freely available, only some people will become alcoholics.

She says rather than a disease, she would call obesity a "condition", where genes interact with the obesogenic environment, sometimes producing disease.

A 2010 report into disease prevention, produced by researchers at the University of Queensland and Deakin University, recommended a 10 per cent tax on certain foods and "front-of-pack 'traffic light' nutrition labelling".

Professor Cowley says there is more high calorie and accessible food than ever before, and at the same time, our relationship with exercise has changed.

"Doing the washing used to be a day's hard labour... we have become too successful in making daily exercise unnecessary," he said.

The World Obesity Federation says "obesity is caused by an energy imbalance; when intake of calories exceeds expenditure of calories, the surplus energy is stored as body weight".

It says "there are a multitude of 'obesogenic' factors contributing to the increased energy consumption and decreased energy expenditure".

These include "declining levels of physical labour as populations move from rural to urban settings and abandon walking in favour of driving, labour-saving devices in the home, and the replacement of active sport and play by television and computer games".

The cost

Professor Funder tells Fact Check it will cost governments significant amounts of money to implement the proper treatments needed by calling obesity a disease.

He warns if governments cannot find political will, then there will be a tsunami of associated disorders and productivity losses.

Weight loss surgery There are a range of Medicare-approved weight-loss surgeries in Australia. They include: Gastric banding: A surgical procedure in which a small silicone band is placed around the top of the stomach to produce a small pouch about the size of a thumb, thereby limiting food intake.

A surgical procedure in which a small silicone band is placed around the top of the stomach to produce a small pouch about the size of a thumb, thereby limiting food intake. Gastric bypass: A small stomach pouch is created to restrict food intake. Next, a Y-shaped section of the small intestine is attached to the pouch to allow food to bypass the lower stomach, the duodenum (the first segment of the small intestine), and the first portion of the jejunum (the second segment of the small intestine).

A small stomach pouch is created to restrict food intake. Next, a Y-shaped section of the small intestine is attached to the pouch to allow food to bypass the lower stomach, the duodenum (the first segment of the small intestine), and the first portion of the jejunum (the second segment of the small intestine). Gastric sleeve: Involves removing the lateral 2/3rds of the stomach with a stapling device. It leaves a stomach tube instead of a stomach sack.

Read more about weight loss surgery options There are a range of Medicare-approved weight-loss surgeries in Australia. They include:Read more about weight loss surgery options here

The Australian Government already subsidises weight loss surgery for severely obese people. The Medical Benefits Schedule rebates are 75 per cent of the fee for the surgical procedure.

But Professor Funder says severely obese people are not being given access to surgery in public hospitals around the country.

The Monash Centre for Obesity Research and Education recommended to the 2009 parliamentary inquiry that publicly funded access to surgery needed to be addressed as a matter of urgency. "It is unusual for a health problem of such magnitude to have so few options for control or commitment by health authorities," the report noted.

Of the 20,000 weight loss surgeries that took place in Australia in 2013 only 1,000, or 5 per cent, took place in the public health system, Professor Funder says.

While Professor Campbell does not agree with labelling obesity a disease, she says there is good evidence to show that some types of bariatric surgery, particularly gastric bypass, have good results in helping severely obese people.

The National Health and Medical Research Council guidelines for clinical management of obese people say "bariatric surgery is more effective in achieving weight loss in adults with obesity than nonsurgical weight loss interventions".

Professor Swinburn says: "Not calling obesity a disease means it does not get the serious consideration it deserves and patients are missing out on important treatments."

A 2010 report by the University of Queensland and Deakin University recommended gastric banding as a treatment for severely obese people.

It said if 25 per cent of severely obese people took up gastric banding, the cost to the health sector would be $3.7 billion. But it said this would be compensated by "large cost offsets from averting future disease ($2.9 billion)".

Another potential treatment for obesity is drug therapy.

In Australia one anti-obesity drug Orlistat is available. Professor Cowley, an advocate of labelling obesity a disease and someone who has helped develop obesity drugs, argues that "high blood pressure is a disease that is treated with medication; obesity should not be any different".

He tells Fact Check that a new drug, Contrave, approved on September 10 by the United States Food and Drug Administration, has shown to result in an average weight loss of 4 per cent a year by curbing people's appetite.

The bottom line

Calling it a disease, rather than a risk factor for diseases like diabetes or cancer, would (in my opinion) not be helpful. Professor Boyd Swinburn

Experts are lobbying for obesity to be labelled a disease in order for Australians to have better access to treatments including surgery, medication and comprehensive plans from GPs.

Professor Swinburn says: "The decision on calling it a disease for reimbursement purposes is a government one. Calling it a disease, rather than a risk factor for diseases like diabetes or cancer, would (in my opinion) not be helpful because of the risks of over-medicalising the problem."

Professor Campbell cautions against calling it a disease because of the people with obesity whose health is not affected.

And the World Obesity Federation says: "It is valid to recognise the public health problems of obesity which indicates that drugs and surgery are not the only approaches to combating the problem. However, arguments for the non-disease state may stem from prejudice inferring that the condition is self-induced and therefore not meriting medical intervention."

The verdict

Associate Professor Dixon's claim that "we are treating a chronic disease" is debatable.

Topics: obesity, health, diseases-and-disorders, federal-government, australia, united-states