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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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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Friday, August 8, 2014

Healthy Obesity: More Questions Than Answers?

sharma-obesity-visceral-fat-mriRegular readers will be well aware of the evidence that a subset of people living with obesity can be remarkably healthy despite carrying a rather large amount of body fat.

This issue of “healthy obesity” was the topic of the 13th Stock Conference of the International Association of the Study of Obesity, the proceeding of which are now published in Obesity Reviews.

As the authors note,

“The ‘healthy obese’ phenotype was described in the 1980s, but major advancements in its characterization were only made in the past five years. During this time, several new mechanisms that may be involved in health preservation in obesity were proposed through the use of transgenic animal models, use of sophisticated imaging techniques and in vivo measurements of insulin sensitivity. However, the main obstacle in advancing our understanding of the metabolically healthy obese phenotype and its related long-term health risks is the lack of a standardized definition.”

The latter is a real problem because finding people with obesity, who are truly metabolically and otherwise healthy becomes harder the higher the BMI gets – this makes the study of this phenomenon rather challenging.

Nevertheless,

“One of the most consistent characteristics of metabolic health in obesity across studies in humans is reduced liver lipid. This is likely the consequence of increased capacity for storing fat coupled with improved mitochondrial function in adipose tissue and decreased de novo lipogenesis in liver. This can also result in decreased deposition of lipids, including bioactive species, in skeletal muscle. Decreased adipose tissue inflammation with decreased macrophages and a unique T-cell signature with an anti-inflammatory circulating milieu were also suggested to characterize metabolic health in obesity. Anecdotal data support a possible role for healthier lifestyle, including increased level of physical activity and healthier diet. It remains to be established whether a favourable metagenomic signature is a characteristic of metabolic health in obesity.”

Finland’s, Dr Kirsi Pietiläinen explained that,

“..three energy dissipation pathways, oxidative phosphorylation, fat oxidation and amino acid catabolism showed preserved pathway activities in subjects who are MHO at a level similar to their lean counterparts. In contrast, these pathways were significantly down-regulated in adipose samples from obese twins with metabolic disturbances. Another potential hallmark of metabolic health, a favourable inflammatory profile of the adipose tissue was also observed in the MHO twins. Also, the fat cells of the MHO twins were smaller with evidence of more active differentiation processes within the fat tissue. As multiple mitochondrial pathways are vital in adipocyte differentiation [29], it is possible that mitochondrial malfunction impairs the development of new fat cells, which in turn results in an inability of the adipose tissue to expand under conditions of energy excess. This failure of fat cell proliferation has long been suspected to constitute the framework for ectopic fat storage, insulin resistance and type 2 diabetes.”

Other speakers discussed other aspects including immune function and microbiata in this phenomenon.

Finally, the authors concluded that,

“identifying underlying factors and mechanisms associated with this phenotype will eventually be invaluable in helping the scientific and medical community understand factors that predispose, delay or protect obese individuals from metabolic disturbances. It is essential to underscore that the MHO concept presently only address the cardio-metabolic risks associated with obesity; it is therefore important that patients who are MHO are still very likely to present many other obesity-related complications such as altered physical and/or physiological functional status, sleep problems, articulation and postural problems, stigma, etc. Importantly, the MHO concept supports the fact that classification based on excess adiposity per se (e.g. BMI or body composition if available) should be supplemented with obesity-related comorbidities, e.g. with fasting insulin as proposed by the Edmonton obesity classification system.”

Certainly a space to watch as we learn more and more about the “healthy obesity” phenotype.

@DrSharma
Edmonton, AB

ResearchBlogging.orgSamocha-Bonet D, Dixit VD, Kahn CR, Leibel RL, Lin X, Nieuwdorp M, Pietiläinen KH, Rabasa-Lhoret R, Roden M, Scherer PE, Klein S, & Ravussin E (2014). Metabolically healthy and unhealthy obese – the 2013 Stock Conference report. Obesity reviews : an official journal of the International Association for the Study of Obesity PMID: 25059108

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Friday, July 11, 2014

Is Weight Gain Typical in Atypical Depression?

sharma-obesity-depressionDepression or major depressive disorder (MDD) is not only one of the most common psychiatric problems, it also comes in many flavours.

While melancholic or “typical” depression is characterized by a loss of pleasure in most or all activities (anhedonia), a failure of reactivity to pleasurable stimuli, psychomotor retardation and a strong sense of guilt, “atypical” depression is characterized by mood reactivity (paradoxical anhedonia), excessive sleep or sleepiness (hypersomnia), a sensation of heaviness in limbs, and significant social impairment as a consequence of hypersensitivity to perceived interpersonal rejection.

An important further distinction is that “typical” depression is commonly associated with loss of appetite and weight loss, whereas “atypical” depression typically involves increased appetite (comfort eating), often with significant weight gain.

Now a study by Aurélie Lasserre and colleagues from Switzerland, published in JAMA Psychiatry, looks at the risk for weight gain in patients with different forms of depression.

The prospective population-based cohort study, included 3054 randomly selected residents of the City of Lausanne (mean age, 49.7 years; 53.1% were women) with 5.5 years of follow-up.

Depression subtypes according to the DSM-IV, as well as sociodemographic characteristics, lifestyle (alcohol and tobacco use and physical activity), and medication, were elicited using the semistructured diagnostic interviews.

As expected, only participants with the “atypical” subtype of MDD at baseline had a higher increase in adiposity and were about 3.75 times more likely to have developed obesity during follow-up than participants without MDD.

This association remained robust even after adjustment for a wide range of confounders.

Thus, as the authors note,

The atypical subtype of MDD is a strong predictor of obesity. This emphasizes the need to identify individuals with this subtype of MDD in both clinical and research settings. Therapeutic measures to diminish the consequences of increased appetite during depressive episodes with atypical features are advocated.

Although we should be wary of those antidepressants that can cause weight gain, an early diagnosis and treatment of atypical depression may well prevent further weight gain and perhaps facilitate weight loss in patients with atypical depression.

Clearly, screening for “atypical” depression must be an essential part of obesity assessment and management.

@DrSharma
Edmonton, AB

ResearchBlogging.orgLasserre AM, Glaus J, Vandeleur CL, Marques-Vidal P, Vaucher J, Bastardot F, Waeber G, Vollenweider P, & Preisig M (2014). Depression With Atypical Features and Increase in Obesity, Body Mass Index, Waist Circumference, and Fat Mass: A Prospective, Population-Based Study. JAMA psychiatry PMID: 24898270

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Tuesday, July 8, 2014

Does BMI Underestimate Adiposity in Kids?

sharma-obesity-kids-scale2Regular readers are well aware of my reservations regarding the use of BMI as a diagnostic parameter in clinical practice. After all, while BMI may tell us how big someone is, it certainly is not a good measure of how sick someone is.

But to be honest, BMI was never intended as a measure of disease – it was (at best) introduced as a surrogate measure of adiposity (fatness).

Nevertheless, supporters of BMI continue to argue that it is still a good measure of fatness and as such should remain part of standard assessment – even in kids.

Now, a paper by Javed and colleagues, published in Pediatric Obesity, examines how well BMI performs as a means to identify obesity as defined by body fatness in children and adolescents.

The authors conducted a systematic review and meta-analysis of 37 studies in over 53,000 participants assessing the diagnostic performance of BMI to detect adiposity in children up to 18 years.

While the commonly used BMI cut-offs for obesity showed showed a high specificity (0.93) to detect high adiposity, the sensitivity was much lower (0.73) – particularly in boys.

This means that kids who exceed the current BMI cut-offs are indeed very likely to have fatter bodies (for what it’s worth).

On the other hand, relying on BMI cut-offs alone will miss as many as 25% of kids whose body fat percentage exceeds current definitions of adiposity.

Thus, assuming that bod fatness or adiposity is indeed a clinically useful measure of health, the use of BMI alone will ‘underdiagnose’ adiposity in a significant proportion of kids (especially boys) who may well be at risk from excess fat.

A word of caution about fatness is certainly in order – as in adults, much depends on exactly where the fat is located (abdominal or ectopic vs. subcutaneous) and other factors (e.g. cell size, inflammation, insulin sensitivity, etc.).

Thus, even if BMI was a perfect measure of body fat, it would probably still require further examinations and tests to determine exactly whether or not this “extra” fat poses a health risk.

As in adults, a clinical staging system similar to the Edmonton Obesity Staging System may be a fat better indicator of determining which kids may need to worry about their body fat and which don’t.

@DrSharma
Edmonton, AB

Hat tip to Kristi Adamo for pointing me to this study

ResearchBlogging.orgJaved A, Jumean M, Murad MH, Okorodudu D, Kumar S, Somers VK, Sochor O, & Lopez-Jimenez F (2014). Diagnostic performance of body mass index to identify obesity as defined by body adiposity in children and adolescents: a systematic review and meta-analysis. Pediatric obesity PMID: 24961794

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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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