Wednesday, October 1, 2014

How Does Stress Affect Eating Behaviour

sharma-obesity-brainOne of the best recognized psychosocial factors tied to food intake is stress. However, this relationship is far from straightforward. While acute stress is often associated with loss of appetite, chronic stress is generally associated with an increase in appetite and weight gain.

Now, a series of articles assembled in Frontiers in Neuroendocrine Science by Alfonso Abizaid1 (Carlton University, Canada) and Zane Andrews (Monash University, Australia), describe in detail the rather complex neuroendocrine factors that link stress to changes in ingestive behaviour.

The series includes articles on the role of neuroendocrine factors like GLP-1, NPY, ghrelin, oxytocin, dopamin, and bombesin but also articles linking stress-related eating behaviours to adverse childhood experiences, perinatal influences, circadian rhythms and reward-seeking behaviours.

I look forward to some interesting reads over the next few days and hope to summarize some of these articles in subsequent posts.

@DrSharma
Saint John, NB

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Friday, September 19, 2014

Does Mandatory Weight Loss Before Surgery Harm Patients?

weight scale helpMany surgical clinics require “mandatory” weight loss before approving patients for surgery, a requirement for which there is very little evidence that it influences post-surgical outcomes (despite the rather firm belief of many that it does).

While one may perhaps accept the need for pre-surgical weight loss when the primary objective is to make the surgery easier for the surgeon and safer for the patient, of greater concern is the practice in many centres that require “mandatory” weight loss based on the notion that patients need to demonstrate their “suitability” for surgery by achieving an arbitrary amount of weight loss in order to “qualify” and prove themselves “fit” for surgery.

That this latter requirement is not without actual risk for the patient and can lead to significant frustration and disruption of the patient-provider relationship is described in a phenomological study by Nicole Glenn and colleagues, published in Qualitative Health Research.

The study is based on in-depth interviews with seven candidates considering bariatric surgery and describes their lived experience and views about what the requirement to lose weight in oder to obtain surgery meant for them.

The article begins with a touching account of one patient:

“The surgeon says, “We need you to get your weight down a little more before we can approve you for surgery.” I fight back the tears as I drive home. Then I think, “I have to do this. I need this surgery.” I work my ass off; I eat nothing but salad for three weeks while I prepare real food for the rest of my family. I go to the gym late at night and settle for five hours sleep because there is no other time in my day with two small children to care for and a husband who works long hours. I struggle, but I’ll do whatever I have to. I come back for my next visit with the surgeon, and I’ve lost more than he had asked me to, yet he doesn’t even notice. He doesn’t comment on my weight at all! He says, “You’ll hear from my office with a surgical date.” That’s it?”

The paper focusses on four themes that emerge from the narratives.

1. Nod your head and carry on:

“[I know a few people who’ve had the surgery, and they all tell me that same thing—just do what you are told! I ran into a friend who had the surgery and was telling him about my frustrations. He said, “If the clinic staff want you to lose five pounds then you need to get the five pounds off and don’t put your personal opinion in there. Just nod your head and carry on.”]“

This behaviour, while understandable, can have unintended consequences for the patient-client relationship:

“To become perfect, to appear to be the ideal patient, a person might find it necessary to act the part. Is it possible to show who one really is when it is the ideal patient who needs to be seen? A person who waits to have bariatric surgery, who feels the need to prove him- or herself to access the surgery, might also find it necessary to hide or become secretive, to leave things out of the food journal or the stories told.”

“Imagine if one awaiting a hip replacement, for example, was first obligated to walk without pain? Why then would one be required to lose weight before weight loss surgery—to do the very thing the surgery provides? To get help, a person must reveal her struggle to the nurse, to name it, and in so doing to show herself as a failure. Such a person finds that she has no other choice. Alone, she cannot lose the weight, and without weight loss, the surgery will not happen. Nevertheless, in revealing this struggle, she risks losing the very thing she hopes to gain.”

2. Waiting and Weighing: Promoting Weight Consciousness to the Weight Conscious:

This section deals with the negative impact that this practice has by reinforcing focus and obsession with numbers on the scale when the real focus should be on health behaviours.

3. Paying For Surgical Approval Through Weight Loss:

“[I feel as if the surgery is being held for ransom, and if I don’t behave perfectly, I won’t get a chance. I mean, I see them obsessing over my charts and journal. No one even tries talking to me. The nurse and psychologist tell me, “No black or white thinking,” but here they are practicing exactly that!]“

“The irony of the perfect behavior required to lose weight and ultimately access weight-loss surgery amid suggestions to reject black and white thinking is not lost on the woman who waits. She should resist the urge to see the world as all or nothing, either this or that, and instead accept the complexities of the grey that exists in the world between black and white, yet she knows that she either loses weight or she loses surgery. It is black or white.”

4. Presurgical Weight Loss and Questioning the Need for Weight-Loss Surgery Altogether:

This section addresses the issue that patients, who do manage to lose substantial weight before surgery, may be faced with having to reconsider the need for surgery altogether thereby increasing internal conflict and enhancing uncertainty as to whether they have made the right decision to have surgery in the first place.

This is clearly a paper that all practitioners in bariatric clinics should read and be aware of.

As the authors point out, given the lack of good evidence that presurgical weight loss has any relevant impact on surgical or post-surgical outcomes, it may be high time to reconsider this potentially harmful practice.

@DrSharma
Edmonton, AB

ResearchBlogging.orgGlenn NM, Raine KD, & Spence JC (2014). Mandatory Weight Loss During the Wait For Bariatric Surgery. Qualitative health research PMID: 25185162

 

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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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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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Monday, September 1, 2014

Guest Post: Emotional Distress And Weight Gain

Erik Hemmiingsson, PhD, Obesity Research Centre, Karolinska Institute, Stockholm, Sweden

Erik Hemmiingsson, PhD, Obesity Research Centre, Karolinska Institute, Stockholm, Sweden

Today’s guest post comes from Erik Hemmingsson, PhD,  a Group Leader at the Obesity Center, Department of Medicine, Karolinska Institute, Stockholm, Sweden. His group studies the role of psychological and emotional distress in weight gain and obesity by mapping life events that influence stress, metabolism and body weight. Erik has a PhD in Exercise and Health Sciences from the University of Bristol (2004) and a PhD in Medicine from Karolinska Institutet.

I work as a researcher in a specialized obesity treatment center at a university hospital in Sweden. My job is to develop new and more effective treatment and prevention methods so that we can hopefully confine obesity to the history books some day.

For many years I mostly did studies on behaviour therapy combined with low energy diets. Since this did not result in any major breakthroughs, I decided to try something a little different.

I had been aware of that many of our patients had experienced difficult childhoods. There were so many sad stories, but I didn’t fancy doing any research on the topic, it was too painful. But then my attitude gradually started to change about a year ago. It was clear that our current treatment methods were woefully ineffective, but I also became more receptive to all those troublesome stories from the patients. Enough was enough, it was time act. So, like Neo in the Matrix movies, I decided to take the red pill, and delve deeper into the very uncomfortable subject of childhood abuse and adult obesity.

I searched the literature and quickly saw that there were more than enough studies for a systematic review and meta-analysis. I enlisted the help of Dr Kari Johansson and Dr Signy Reynisdottir, and got to work.

What we found very much confirmed all those clinical observations, i.e. there was a very robust association between childhood abuse and adult obesity. The association was also very consistent across difference types of abuse, with an increased risk of about 30-40%. There was also a dose-response association, i.e. the more abuse, the greater the risk of obesity.

While this study confirmed something very important, it was also clear that not everyone who suffers childhood abuse develops obesity, or that all obese individuals have suffered childhood abuse, or the effects would have been even more pronounced. But for me, the study proved that stressful childhood experiences can easily manifest as obesity many years later. This led me even deeper down the rabbit hole. I wanted to know why.

I decided to try and piece together different ideas about how obesity develops in relation to stressful life events. This resulted in a new conceptual causal model consisting of six different developmental stages. Like many diseases, obesity development is more likely when there is socioeconomic disadvantage (applies mainly to Europe and North America). Socioeconomic disadvantage can very easily trigger a chain of events that include adult distress, a disharmonious family environment, offspring distress, psychological and emotional overload, and finally disruption of homeostasis through such mechanisms as maladaptive coping responses, stress, mental health problems, reduced metabolism, appetite up-regulation and inflammation.

Much more research is needed to validate the model, but if there is some truth to this theory, which the childhood abuse meta-analysis clearly suggests that there is, then my hope is that we can use this information to develop more effective treatment and prevention methods.

My other hope is that some of the truly horrendous stigma, shame and discrimination that the obese experience can gradually be alleviated, since there is clearly a lot more to obesity etiology than the commonly held preconception that obese individuals are merely lazy and overindulgent.

After having done all this work on obesity etiology, I would say that my top-3 reasons we have an obesity epidemic (in no particular order) are socioeconomic inequality, the junk food invasion, and psychological and emotional distress patterns (usually established at an early age). And when you combine all three you have the perfect storm for weight gain.

You can find more information at my blog at www.holisticobesity.com

Erik Hemmingsson,
Stockholm, Sweden

References:

Hemmingsson E, Johansson K, Reynisdottir S. Effects of childhood abuse on adult obesity: a systematic review and meta-analysis. Obesity Reviews (epub 15 August 2014).

Hemmingsson E. A new model of the role of psychological and emotional distress in promoting obesity: conceptual review with implications for treatment and prevention. Obesity Reviews 2014, 15:769-779.

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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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