Is obesity a disease?

Few would argue about the dangers of obesity, but many disagree on how it should be defined

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Australia is in the grips of an obesity epidemic, with prevalence rates jumping from 18.5% to 27.9% over the last two decades.

Being obese or overweight has now overtaken smoking as the second highest contributor to burden of disease, behind dietary risks, but as a nation we have yet to serious action on this.

There are few prime-time advertising spots designed to educate people of the risks, or billboards promoting treatment options.

For many clinicians and medical groups, the time has come to start calling obesity a disease, and treating it with the legitimacy it deserves.

In the last few years, the American and Canadian medical associations have reclassified obesity as a disease, as opposed to a chronic condition or risk factor. But the topic is controversial, and in Australia, neither the government, the AMA nor the RACGP have followed suit.

Those who believe obesity should be considered a disease argue that it is an impairment of normal functioning, that it has a genetic basis and that it is associated with poorer quality of life and comorbidities.

Others argue that obesity does not fit the criteria of a disease and that the reclassification would be a case of medicalising a risk factor. They say weight gain is the response of a well-functioning body to an obesogenic environment.

But whatever we have been doing in the last two decades hasn’t been working, and something needs to change, according to Dr Georgia Rigas, chair of the RACGP’s Obesity Management Network.

If nothing changes in our approach to combatting obesity, Australia will see 2.4 million more people with obesity by 2025, costing society an extra $87.7 billion in direct and indirect costs, according to an analysis by PricewaterhouseCoopers.

One way to change that would be to recognise obesity as a chronic disease, Dr Rigas says. Doing so would legitimise the chronicity and the science behind our understanding of obesity, and hopefully overcome some of the stigma and bias surrounding it. “There is a lot of shame and guilt that patients with obesity carry, and this drives their reluctance to access medical help,” Dr Rigas says.

“BEACH data shows that less than 1% of GP consultations are centred around the issue of weight and obesity management, even though we know that almost a third of Australian adults have obesity.”

Defining obesity as a disease would acknowledge that the body physiologically defends against weight loss.

“People with misinformation and a lack of knowledge often wrongly presume that obesity is a lifestyle choice, and it’s not. Patients don’t choose to have obesity and its sequelae, both physical and psychological,” Dr Rigas says.

There is a lot of shame and guilt that patients with obesity carry, and this drives their reluctance to access medical help.

This doesn’t negate the fact that patients still need to be accountable for their choices, but it reflects that obesity is a complex problem, requiring the backing of medical professionals, she says.

Professor Anna Peeters, former president of the Australian and NZ Obesity Society, agrees that calling obesity a disease would help combat the stigma that undermines its adequate treatment.

Evidence from the US and Canada seems to support this, with doctors appearing to be more willing to treat obesity now and patients more willing to identify as having obesity because they see it as having tangible treatment outcomes, the professor of Epidemiology & Equity in Public Health at Deakin University says.

And it’s not just the public who remain under the misconception that obesity is primarily a result of a lack of personal willpower.

Despite numerous reports on the cost of obesity to society, politicians still trot out the line about individual responsibility to counter attempts to improve the problem at a societal level.

For example, Liberal MP Ewan Jones opposed the introduction of a healthy food rating system in 2014, saying “It’s not the government’s fault that I’m fat. It’s my fault and I live with the consequences”.

The debate centres on the semantics of the word “disease”. Some argue that obesity should be considered a disease in the same way that diabetes is considered a disease – both are conditions that cause a whole series of complications.

A high BMI contributed to more than half the total burden of disease attributable to diabetes, more than one third due to chronic kidney disease, almost one quarter due to coronary heart disease and 17% of the burden due to stroke, the Australian Burden of Disease Study found in 2011.

The counterargument is that obesity doesn’t meet the criteria for a disease because it isn’t a dysfunction of the body. Instead, the body is normally responding to the environment that it is in.

The analogy here is with hypertension. Hypertension is an abnormality that is treated because it is a risk factor for stroke and heart disease. In a similar way, obesity is a serious condition that should be treated whether it is considered a disease or not, just like hypertension or hypercholesterolemia are.

Research suggests that one in three obese people may not have any risk markers for type 2 diabetes or heart disease, and some worry that these people may unnecessarily get labelled “diseased”.

Another potential risk is that being labelled diseased may engender fatalism by the patient, who may then abandon attempts at improving diet and increasing exercise.

Similarly, reclassifying obesity as a disease could medicalise the problem, shifting the attention purely to treatment rather than prevention.

There is no possibility that we have the capacity in Australia, or elsewhere, to treat our way out of this disease, Professor Peeters says. With almost a third of the population obese, that is not going to be a cost-effective approach.

“So at the same time as we improve our treatment options, we really need to have a much stronger prevention response in Australia,” she says.

“At the moment, we don’t have a national obesity plan, we have no obesity prevention strategy and we’re lagging behind other countries who are doing things like introducing a sugary drinks tax.

“It’s very clear that unless we introduce some of these strong measures to improve the population’s diet and activity levels, we really won’t be able to dent this problem with treatment alone.”

But just because something has the label of disease, it doesn’t mean that all patients would be forced into medical intervention.

Just like any disease, patients would be managed by their treating doctor, who can assess what type of treatment, if any, is needed.

Nobody is saying that every person with obesity should be put on drugs or undergo bariatric surgery straight off the bat. If a person is otherwise healthy, then lifestyle interventions and a discussion about exercise and diet may be the best option.

Regardless of whether someone has metabolic disease or not, there are other health conditions associated with carrying around too much weight.

Osteoarthritis, sleep apneoa and lymphedema are all examples of mechanical problems associated with obesity.

The science

Reclassification will acknowledge the scientific developments in our understanding of obesity, advocates say. Over time, we are coming to understand the cascade of changes that occur to a body undergoing weight gain.

“We now know a lot more about excess adipose tissue and what it does than we did 20 years ago,” says Dr Rigas.

“We used to just think they were fat cells and they were for the storage of energy, but now we know that fat cells and their contents are hormonally active cells in themselves,” she says, pointing to the fact that they send signals to the body and brain to regulate appetite and energy levels.

“So dysregulation is definitely there, and that’s why I think obesity would meet the criteria for disease.”

Obesity is now considered a recurrent, often lifelong problem that, like diabetes, can’t be fixed overnight nor with simple lifestyle interventions.

We now know that 80-95% of obese people who lose weight regain it again eventually, leading researchers to call weight loss “obesity in remission” rather than recovery.

Once you’ve had obesity, you’ll be biologically different from those who haven’t, even if you’ve now lost that weight.

While obesity may be the result of a single gene defect for some, the vast majority of people with obesity have more subtle genetic variations occurring in many genes. In addition, it appears that prenatal and postnatal environmental factors can modify gene expression.

“That is how the genes work,” says Associate Professor Tania Markovic, director of Metabolism & Obesity Services at Royal Prince Alfred Hospital. “These genetic variations affect multiple sites involved in energy regulation, for example there are people who exercise more or less efficiently, genes seem to control the amount we fidget and how much energy we use to control our posture, and there are animal data suggesting that, depending on your genetic makeup, you may respond to a particular diet differently.”

Environmental changes have also been dramatic over the last 50 years and have significantly contributed to the obesity epidemic. If you consider the way our food has changed, our leisure pursuits and the jobs we do.

The way our cities and towns are designed can also make it more difficult to exercise, Professor Markovic says.

The way we engage with the internet and our habits with devices is not only a problem in that they encourage sedentary behaviour, but watching a bright screen later in the day can have an adverse effect on sleep quality, and we know that poor sleep changes appetite and our metabolism, she says.

The money

The national summit on obesity last year, convened by presidents of Australian medical colleges, listed, as the highest priority, recognising obesity as a chronic disease and not a lifestyle choice.

“This should be reflected in the case-mix classifications and funding mechanisms under the Medical Benefits Schedule (MBS) and Pharmaceutical Benefits Schedule (PBS) enabling health professionals to better manage the disease”.

To be eligible for care under chronic disease management is up to the discretion of the GP, as long as the individual has a chronic medical condition that is likely to be present for six months or more.

“People will argue that within the chronic care item numbers it is possible to offer care plans for people with obesity provided they have some sort of co-existent comorbidity, but it is quite clear that those Medicare items are actually pretty under prescribed anyway,” says Professor Timothy Gill, research programs director at the Boden Institute of Obesity, Nutrition and Exercise.

Both GPs and other health professionals complain that there is very little reimbursement for the amount of work required to undertake extensive care plans and provide services.

“Another concern is that what this system does is dissuade any focus on weight management at any stage of the development of weight problems,” says Professor Gill.

It is clear that the earlier you intervene in people who have a weight problem, the more likely you are of having success, he says.

“If you delay intervention in people with a serious weight problem until they get comorbidities, it’s ridiculous. Because it’s more difficult to treat that obesity, and now they’ve got coexisting health problems which also require attention and make it more difficult to manage their health generally.”

Another priority stressed at the obesity summit was the need for early, and better access to, services treatments, in part through government-subsidised anti-obesity medications. While there are three TGA-approved medications to treat obesity, not one is covered by the PBS.

“We only have a very small fraction, less than 2%, penetrance of bariatric surgery in Australia, and of that, only 15% is done in the public hospital system,” Dr Rigas says.

Without government help, patients may be out of pocket $200 to $400 per month for anti-obesity medication, or $10,000 to $20,000 for bariatric surgery.

“There is a lot of inequity here, especially for people with lower socioeconomic backgrounds, who are the ones primarily affected,” Dr Rigas says.

Without better funding we are basically telling patients with class III obesity, who are carrying 50 to 100kgs more than they should, that just exercise and diet should be able to fix them.

While Dr Rigas sympathises with government bodies that are scared that this change will open a Pandora’s box, not everyone needs all type of therapies.

There are staging systems, such as the Edmonton Obesity Staging System, that have been validated and found useful in risk stratifying patients to determine suitability for various treatment options.

The hope is that declaring obesity a disease will generate a sense of importance and urgency to the problem. Unfortunately not everyone agrees on the definition of “disease”, let alone the definition of obesity.

People get into detailed arguments about whether obesity meets all the conditions of what a disease is, Professor Gill says. “But at one stage homosexuality was a disease but depression wasn’t, so there is no clear definition of what a disease is. People say obesity is a BMI greater than 30, but that’s not what it is. That’s like saying diabetes is a fasting blood sugar greater than 7 mmol/L.”

Diabetes is a metabolic condition where the body is incapable of regulating blood glucose, and it is measured by fasting blood sugar.

“But the problem is not the fasting blood sugar, it is the metabolic disturbance,” Professor Gill says.

“So we are mixing up the way we define it, and what the condition actually is. So if the question is ‘should it be recognised as a disease for Medicare rebates?’ my answer would be yes,” Professor Gill says.