Tuesday, September 16, 2014

Is Food Addiction Better Described As Eating Addiction?

sharma-obesity-addiction-typesThe term “food addiction” has found its way into both the scientific and popular literature.

Now, a thoughtful paper by Johannes Hebebrand and colleagues, published in Neuroscience & Biobehavioral Reviews, argues that there is in fact little evidence for addiction to “food” per se (as you would see in addiction to a specific substance) and that therefore, it may be better to describe the addiction-like overconsumption of food as a behavioural addiction, in this case, an addiction to eating.

Eating is intrinsically rewarding and reinforcing, and food consumption is well-known to activate the reward system in the brain; this applies particularly in the physiological state of hunger. It is easy to see that the rewarding properties of food and their activation of the reward pathway might lead intuitively to the idea that food substances may have addictive properties. However, just because eating behavior engages these reward systems, it does not necessarily follow that specific nutrients (substances) are able to evoke a substance addiction. Instead, the complex activation of the reward system as the initial step of the process ending in addiction can be viewed as being dependent on eating (subjectively) palatable foods irrespective of their nutritional/chemical composition.”

Per se, foods are nutritionally complex and there is hardly any evidence to suggest that under normal physiological circumstances humans crave specific foods in order to ingest a specific ‘substance’. Instead, the diet of subjects who overeat typically contains a broad range of different, subjectively palatable foods. It can be argued that access to a diversity of foods, especially a diverse range of palatable foods, may be a pre-requisite for the development of addictive-like eating behavior.”

There is currently no evidence that single nutritional substances can elicit a Substance Use Disorder in humans according to DSM 5 criteria. In light of the lack of clinical studies that have aimed to detect addictions to specific nutrients, it cannot as yet be ruled out that a predisposed subgroup does indeed develop such a substance based addiction, which in theory may be substantially weaker than in the case of addictions based on well-known exogenous substances such as alcohol, cannabis, nicotine or opiates. The fact, that clinical case studies do not abound on an addiction like intake of specific nutrients or even specific foods, would suggest that such cases are rare, if they exist at all. Alternatively, the addiction is so weak that it is not adequately perceived and reported as such. This leads to the question as to the boundaries between excessive consumption and the beginning of a true addiction.”

Thus,

“…there is very little evidence to indicate that humans can develop a “Glucose/Sucrose/Fructose Use Disorder” as a diagnosis within the DSM-5 category Substance Use Disorders. We do, however, view both rodent and human data as consistent with the existence of addictive eating behavior. The novel DSM-5 (APA, 2013) currently does not allow the classification of an “Overeating Disorder” or an “Addictive Eating Disorder” within the diagnostic category Substance-Related and Addictive Disorders; indeed, the current knowledge of addictive eating behaviors does not warrant such a diagnosis. However, efforts should be made to operationalize the diagnostic criteria for such a disorder and to test its reliability and validity. It needs to be determined if such a disorder can occur distinct from other mental disorders.”

Overall I believe that reframing the perceived loss of control over food intake often reported by my patients as a “behavioural” rather than a “substance” addiction may be helpful in approaching this rather complex topic and may well open the path to novel therapeutic approaches more consistent with our current understanding of behavioural addictions.

@DrSharma
Vienna, Austria

ResearchBlogging.orgHebebrand J, Albayrak O, Adan R, Antel J, Dieguez C, de Jong J, Leng G, Menzies J, Mercer JG, Murphy M, van der Plasse G, & Dickson SL (2014). “Eating addiction”, rather than “food addiction”, better captures addictive-like eating behavior. Neuroscience and biobehavioral reviews PMID: 25205078

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Monday, September 15, 2014

Update on New Medications for Obesity

sharma-obesity-fda4Last week, while I was off on a brief holiday, two important events took place in the US with regard to obesity medications.

On September 10, the US-FDA granted approval for Contrave, a fixed combination of bupropion and naltrexone, two centrally active compounds, also used in the treatment of addictions.

Then, on September 11, an advisory panel appointed by the FDA, voted strongly in favour of approving the GLP-1 agonist liraglutide at the 3.mg dose for the treatment of obesity.

These two new entities would bring the currently approved prescription medications for the treatment of obesity in the US to six – a dramatic change from just a couple of years ago.

This is still a long shot away from the many effective treatments we have for treating other common conditions (e.g. there are more than 20 prescription medications approved for treating diabetes and almost 100 compounds for the treatment of hypertension).

Why would we need this many different medications for obesity? For the simple reason that not everyone will respond favourably or tolerate all of these compounds.

Given that obesity is a remarkably heterogeneous disorder and that these drugs have distinctly different modes of action, I would not expect all of these medications to work in all individuals.

It is also important to note that all of these drugs work best when combined with intense behaviour modification – no pill will ever serve as a substitute for a healthy diet and a daily dose of moderate to vigorous physical activity. But we also know that the latter alone, will rarely produce sustainable weight loss in the long-term.

Obviously, given the chronic nature of obesity, medications for obesity will need to be used long-term in the same manner that we use medications to treat other chronic conditions (e.g. diabetes, hypertension, etc.).

This means that we will need more long-term data on the efficacy and safety of these compounds.

Nevertheless, there is reason to hope that for many people with obesity related health problems, these new obesity medications will provide much-needed therapeutic options.

@DrSharma
Vienna, Austria

Disclaimer: I have served as a paid consultant and/or speaker for the makers of Contrave and liraglutide.

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Wednesday, September 3, 2014

Can Targeting Estrogen Receptors Alleviate Binge Eating Disorder?

sharma-obesity-mouse-eatingBinge eating disorder, a loss of control of food intake accompanied by dysphoric mood alterations, is more common in women than in men and may account for as much as 40% of severe obesity seen at bariatric centres.

Strangely enough, a new study by Xuehong Cao and colleagues from Baylor College of Medicine, Houston, Texas, published in the Journal of Clinical Investigation, shows that targeting estrogen receptors in the serotonergic neurons of brain centres involved in appetite regulation may alleviate this behaviour, at least in mice.

Previous observations in humans that women with binge eating often suffer from menstrual irregularity, presumably due to impaired functions of ovarian hormones (e.g. estrogens) and that circulating 17β-estradiol levels are inversely associated with binge eating, prompted these investigators to study the role of estrogen in binge eating behaviours in ovarectomised mice.

While estrogen administration resulted in markedly reduced binge eating behaviour in these mice, this effect was absent in genetically modified mice that lacked the estrogen receptor-α (ERα) in the dorsal raphe nuclei (DRN), an area particularly rich in serotonin (5-HT) neurons known to be important in appetite regulation (and sleep).

The researchers also showed that a conjugate that combines GLP-1 and estrogen into one molecule is far more effective in reducing binge eating behaviour than GLP-1 alone (again, this effect was much reduced in ERα KO mice) suggesting that such a conjugate may be used to specifically target GLP-1 receptor neurons, thereby perhaps avoiding any potential adverse effects of estrogen administration.

Obviously, there is a long way from such initial observations in mice to safe and effective treatments in humans.

Nevertheless, these observations should open a new field of interest in finding more effective pharmacological treatments for binge eating disorders or perhaps even more “common-garden-variety” obesity in humans.

@DrSharma
Gambach, Germany

ResearchBlogging.orgCao X, Xu P, Oyola MG, Xia Y, Yan X, Saito K, Zou F, Wang C, Yang Y, Hinton A Jr, Yan C, Ding H, Zhu L, Yu L, Yang B, Feng Y, Clegg DJ, Khan S, DiMarchi R, Mani SK, Tong Q, & Xu Y (2014). Estrogens stimulate serotonin neurons to inhibit binge-like eating in mice. The Journal of clinical investigation PMID: 25157819

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Friday, August 29, 2014

2014 Scopinaro Lecture

Nicola Scopinaro, MD, Professor of Surgery, University of Genoa Medical School, Italy

Nicola Scopinaro, MD, Professor of Surgery, University of Genoa Medical School, Italy

This morning, at the XIX World Congress of the International Federation of Surgery for Obesity and Metabolic Disorders (IFSO2014), I have the great honour of presenting the 2014 Scopinaro Lecture.

This lecture is named after Nicola Scopinaro, who in 1976 performed the first biliopancreatic diversion for the treatment of obesity.

The Scopinaro Lecture is the highest recognition for a non-surgeon to be awarded by IFSO.

In thinking about what to present, I settled on discussing the topic of whether or not obesity is a disease. Looking back over the work that I have done over the past 25 years, I came to realise that the issue of why some people with excess weight develop health problems and others don’t, has indeed fascinated me for a long time.

Initially, this interest was focussed on trying to understand why some people with obesity develop high blood pressure and others don’t. We were indeed able to show that part of this may be explained by differences in the expression of hormones involved in blood pressure regulation from fat tissue.

More recently, as many regular readers are well aware, I have broadened this interest in describing the limitations of BMI and advocating for a clinical staging system that classifies overweight and obese individuals based on how “sick” they are rather than how “big” they are.

Clearly, this work is of considerable interest to those involved in bariatric care (including bariatric surgeons), as it provides a framework for better prioritizing and assessing risk/benefit ratios than BMI or other anthropometric measures alone.

As I point out in my talk,

- The etiology of obesity is complex and multifactorial.

- The physiology of energy regulation is complex and subverts volitional attempts at weight loss.

- Access to obesity prevention and treatments must be driven by the recognised medical needs to address this condition.

- Multidisciplinary management of this life-long disorder requires resources similar to those required for other chronic diseases

In receiving this honour, I am fully aware that all of my work stands on the shoulders of the many researchers and clinicians who came before me and the considerable support and help that I have been fortunate enough to receive from my many students, trainees, colleagues and supervisors.

This award will certainly serve an a strong incentive to continue my work and advocacy for better treatments for obesity and the advancement of bariatric care.

@DrSharma
Montreal, QC

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Thursday, August 28, 2014

Call For Abstracts: Canadian Obesity Summit, Toronto, April 28-May 2, 2015

COS2015 toronto callBuilding on the resounding success of Kananaskis, Montreal and Vancouver, the biennial Canadian Obesity Summit is now setting its sights on Toronto.

If you have a professional interest in obesity, it’s your #1 destination for learning, sharing and networking with experts from across Canada around the world.

In 2015, the Canadian Obesity Network (CON-RCO) and the Canadian Association of Bariatric Physicians and Surgeons (CABPS) are combining resources to hold their scientific meetings under one roof.

The 4th Canadian Obesity Summit (#COS2015) will provide the latest information on obesity research, prevention and management to scientists, health care practitioners, policy makers, partner organizations and industry stakeholders working to reduce the social, mental and physical burden of obesity on Canadians.

The COS 2015 program will include plenary presentations, original scientific oral and poster presentations, interactive workshops and a large exhibit hall. Most importantly, COS 2015 will provide ample opportunity for networking and knowledge exchange for anyone with a professional interest in this field.

Abstract submission is now open – click here

Key Dates

  • Abstract submission deadline: October 23, 2014
  • Notification of abstract review: January 8, 2014
  • Early registration deadline: March 5, 2015

For exhibitor and sponsorship information – click here

To join the Canadian Obesity Network – click here

I look forward to seeing you in Toronto next year!

@DrSharma
Montreal, QC

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In The News

Diabetics in most need of bariatric surgery, university study finds

Oct. 18, 2013 – Ottawa Citizen: "Encouraging more men to consider bariatric surgery is also important, since it's the best treatment and can stop diabetic patients from needing insulin, said Dr. Arya Sharma, chair in obesity research and management at the University of Alberta." Read article

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