Last week, an article in the New York Times with the title “The Obesity-Hunger Paradox“, addressed the issue of food insecurity - or how, not knowing when or where your next meal will come from, can make you overeat - thus promoting obesity.

Interestingly, this month’s issue of OBESITY uses an animal model to illustrate a similar point.

In this study by Xingshenk Li and colleagues from the University of Alabama, one set of mice was first allowed free access to food for six weeks and was then mildly calorie restricted (5%) over three more weeks during which the animals were provided access to food only once a day. In a second experiment mice were either mildly calorie restricted or had free access to food.

Interestingly, one of the big changes in feeding behaviours with calorie restriction was overeating, where the mice ate almost four times the amount of food in a two hour period, than when they had free access to food.

Importantly, despite the overall calorie restriction, the researchers found no change in body weights - rather, the calorie-restricted mice appeared to become fatter, exchanging fat for lean tissue. They also showed a significant reduction in energy expenditure.

The researchers interpret their evidence as supporting the notion that the gorging behaviour in response to food “uncertainity” alters energy partitioning resulting in more effective triglyceride production and fat storage. This altered metabolism may in part be due to the hormonal changes resulting from the “stress” of calorie restriction.

Clearly, these findings should be of interest to those of us who wonder about the long-term effects of caloric restriction, meal skipping, and binge eating.

The study may also explain why chronic (especially intermittent) dieting can be counterproductive and in some individuals paradoxically increase fat stores.

Certainly the study should remind us that any restriction of food intake (whether voluntary or involuntary) can profoundly change our “feeding” behaviour and change the way our bodies handle calories.

The next time you wonder why you or your patients are not losing weight despite restricting calories, remember that there is apparently no end to the tricks our body will come up with to protect its weight.

AMS
Edmonton, Alberta

Regular readers of these pages are well aware of the close link between addictions and some forms of overeating. This topic is now nicely addressed in a commentary by Valerie Taylor (McMaster, Hamilton), Claire Curtis and Caroline Davis (both York University, in this week’s edition of CMAJ.

As they discuss,

“The concept of food addiction, which more accurately may reflect addiction to specific components of food, can be described in much the same way as other addictive behaviours. Both food and drugs induce tolerance over time, whereby increasing amounts are needed to reach and maintain intoxication or satiety. In addition, withdrawal symptoms, such as distress and dysphoria, often occur upon discontinuation of the drug or during dieting. There is also a high incidence of relapse with both types of behaviour.“

To further support their arguments, they cite the many imaging studies showing that specific areas of the reward or mesolimbic system, such as the caudate nucleus, the hippocampus and the insula, are activated both by drugs and by food.

Thus, the easy accessibility of highly palatable foods together with our innate preferences for such foods, can increase the likelihood that vulnerable people will “misuse” food, in much the same way that addicts misuse other drugs to blunt negative emotional states, such as depression, anxiety, loneliness, boredom, anger orinterpersonal conflict.

While the concept of addiction should not negate the role of free will and personal choice, it does provide a rationale for the including addiction screens as a routine part of assessment for obesity. It may also help explain the success of lifestyle programs that incorporate pharmacotherapy or behavioural strategies specifically designed to address the addictive component of this illness.

Thus, as pointed out by Taylor and colleagues, there is not only considerable overlap among the medications shown to interfere with food and drug abuse in animal models, but the many behavioural interventions developed for managing addictions (motivational interviewing, cognitive behavioural therapy and 12-step programs), are increasingly recognised as also being helpful in managing obesity.

Health professionals and decision makers charged with tackling the obesity epidemic would do well to familiarise themselves with the science of addictions and utilize learnings from addiction management in their counseling of patients presenting with excess weight.

AMS
Edmonton, Alberta

Dr. Hei Sook Sul

Yesterday, I had the pleasure of listening to Hei Sook Sul (picture) from the University of California, Berkeley, who spoke at the Alberta Diabetes Institute here in Edmonton (host Dennis Vance).

Sul’s group, which works on better understanding the molecular mechanisms underlying the synthesis of fatty acids, recently identified DNA-PK, a protein kinase that plays a role in DNA repair, as a possible key factor in the activation of fatty acid synthase (FAS), the enzyme that helps convert dietary carbohydrates to fat.

In a paper, recently published in the journal Cell, Sul’s group showed that feeding high-carb diets to mice with a disabled DNA-PK gene resulted in lower levels of body fat than in their normal counterparts. This was evidently due to their inability to convert carbs to fats, a key step when excess calories from carbs need to be stored for future use.

As always, one must be careful in jumping from findings in mice to humans, and although DNA-PK may well seem an attractive pharmacological target to prevent fat accumulation in people who eat high-carb diets, it is important not to forget that this enzyme also plays an important role in DNA repair, a possible critical factor in preventing cells from mutating into cancer cells.

Nevertheless, the elucidation of this important metabolic step - the conversion of dietary carbs to fat - is certainly a major breakthrough in our understanding of how the body metabolizes carbohydrates and definitely provides fascinating new insights into the complex workings of nutritional biology.

AMS
Edmonton, Alberta

Although, in the end I spent less than 24 hrs in the Emirates, one of the highlights of attending the 1st International Abu Dhabi Diabetes Conference, was the opportunity to once again hear David Cummings (Seattle) speak about how bariatric surgery can lead to the remission of type 2 diabetes. Cummings’ talk certainly provided plenty of food for thought on my long flight back to Canada.

As outlined in a newly released Diabetes Surgery Position Statement published in the latest issue of the Annals of Surgery, surgical approaches may well prove to be the treatment of choice in carefully selected patients with poorly controlled type 2 diabetes and a BMI greater than 30.

While the authors of the Statement emphasize the need for more clinical trials to investigate the future role of surgery in diabetes treatment, they also call for further investigations on the mechanisms of surgical control of diabetes (which are far from being fully understood).

Although weight loss itself clearly plays a significant role in the reversal of diabetes generally seen with bariatric surgery, with gastric bypass surgery, this reversal of diabetes often precedes the weight loss and there are likely neuroendocrine consequences to allowing food to bypass the duodenum that may substantially affect glucose metabolism (including regeneration of pancreatic beta-cells).

Thus, a better understanding of exactly how gastrointestinal surgery “cures” diabetes, will hopefully also open new avenues for pharmacological treatments that can mimic the effects of surgery in these patients.

Indeed, certain gut-hormones, which are known to be dramatically affected by gastric bypass surgery (e.g. GLP-1), have already been shown to have a beneficial effect both on diabetes and weight management (e.g. liraglutide).

Health professionals who want to learn more about this topic should consider attending the upcoming First Canadian Summit Metabolic Surgery for Type 2 Diabetes to be held in partnership with the Canadian Obesity Network and the Canadian Diabetes Association at the Hôtel Le Centre Sheraton, Montréal, May 6-7, 2010.

To watch a recent episode of 60 Minutes on CBS, which features interviews with Cummings and others discussing the surgical approach to type 2 diabetes, click here.

Very much appreciate hearing from my readers on their thoughts regarding whether or not diabetes surgery (vs. lifelong medications or injections) will significantly change how we treat diabetes in the future.

AMS
Edmonton, Alberta

Arab Food Pyramid

When we think of the global obesity epidemic, we tend to conjour up images of of US-Americans, literally hefting along excess pounds as they go about their lives across America. We may also recall that Canada and most other Western countries have a problem.

But, interestingly, nowhere is the obesity problem as big as in the countries of the Gulf Region and the Middle East (exceeded perhaps only by populations on remote Oceanic islands).

According to the United Arab Emirates global school-based student health survey (GSHS) 2005 fact sheet, over 30% of 13-15 year olds exceed the 85th percentile for body weights. The adult population (though it is hard to find accurate statistics) apparently does not fare much better.

Why, you may wonder, am I interested in this?

Because tonight I am heading out from Munich to speak on Saturday at the 1st International Abu Dhabi Diabetes Conference, in the United Arab Emirates.

Although the conference focusses on diabetes, it is obvious that the prime driver of the diabetes epidemic in that region of the world (as elsewhere) is the obesity crisis.

It is therefore not surprising that the organisers have opted to include sessions on obesity assessment and management (although most of the conference of course focusses on diabetes management, which I have often described as “palliative care”).

As should be obvious to anyone who has recently visited the UAE, population-based prevention measures in a society that spends most of its time indoors (I would too when it’s 40-50 degrees C outside) and enjoys food as one of the only officially endorsed “vices” (there are tough restrictions on alcohol, gambling and other worldly “pleasures”), is lilkely to be challenging if not simply impossible.

Given that the Arab susceptibility to obesity appears similar to other Asians in that they appear more prone to abdominal obesity with all its dire metabolic consequences, diabetes may in fact be the least of their worries.

I look forward to attending the meeting and learning more about the Arab “diabesity” epidemic from my friends and colleagues in the Emirates.

AMS
Munich, Germany

Today, I am attending the 8th World Congress on Trauma, Shock, Inflammation and Sepsis in Munich, Germany.

Interestingly, this conference features a whole series of seminars on the interdisciplinary management of obesity (under the rather unfortunate title ‘Fat Man – We Will Help You’ [sic]).

I have been invited to chair and speak at the session on medical therapy, but there are also sessions on adipose tissue biology, perioperative management, bariatric surgical procedures, and the emergency management of bariatric patients.

As I often say in my presentations to colleagues: it does not matter what discipline in medicine you practice – you will be seeing an increasing number of heavier patients with their own issues and complications.

The fact that a world conference on trauma should devote this much time to sessions on obesity assessment and management is clearly to be commended in the light of the global obesity epidemic.

The more all health professionals learn and understand the complexities and problems posed by heavier patients, the better we can serve this particularly vulnerable patient population.

AMS
Munich, Germany

Richard Lehner

New findings published by University of Alberta researchers in a recent issue of Cell Metabolism may point to a new pharmacological target for reducing fat and blood sugar levels in blood while also positively affecting energy expenditure (at least in mice).

The research team, led by Richard Lehner (picture), showed that genetically knocking out an enzyme called TGH (triacylglycerol hydrolase), which is normally involved in helping the liver (and other tissues) process fat, not only reduces blood fat levels but also improves insulin sensitivity and glucose tolerance.

Interestingly, the animals were also better able to utilize glucose and, despite consuming significantly more energy, they displayed increased locomotor activity and consequently did not gain weight.

As always, such studies in mice must be taken with a grain of salt in that there is usually a long way to go before (if at all) these findings pan out in new treatments for humans.

On the other hand, these studies do demonstrate the potential of TGH as a therapeutic target for lowering blood lipid levels and possibly body weight through a novel pathway.

AMS
Munich, Germany

In medical school I learnt that we have four senses of taste: sweet, sour, salty, and bitter.

Several years ago a fifth sense, umami, was officially added to this list. Umami is stimulated by glutamate (as in MSG) and apparently allows us to taste protein (as in meat, sea food, or cheese).

Now, Jessica Stewart and colleagues from Deakin University in Australia show that a sixth sense, i.e. the ability to orally “sense” the fat content of foods may explain differences in fat preferences (British Journal of Nutrition).

Indeed, previous studies in animals have suggested that oral hypersensitivity to fatty acids (the building blocks of fat) are associated with decreased fat intake and body weight.

In the current study, the investigators first examined the taste thresholds for different types of fatty acids (olate, linolate, and laurate) in 31 normal weight subjects and classified them as hypo- or hypersensitive. Subjects also completed a fat ranking task using custard containing varying amounts (0, 2, 6 and 10 %) of fat.

Hypersensitive subjects reported lower energy and fat intakes, had an increased ability to rank the custards based on fat content and also had a lower BMI levels.

These data suggest that the increased ability to detect nutritional fat may result in lower energy and fat intake, which in turn may result in lower body weights.

Obviously, the idea here is that people who are less sensitive to fat are likely to need more fat in their foods to get that same level of enjoyment as people with more sensitive fat receptors. Because of fat’s high caloric content, this means that they may in the end also end up with more calories, and thus, weight gain.

I can think of a number of interesting questions that these findings may prompt:

1) Is the increased ability to taste fat genetic or are changes in fat-sensitivity determined by habitual fat intake (gustatory plasticity)?

2) Does weight loss affect people’s ability to taste fat (resulting in them searching out fattier foods when on a diet)?

3) Does going on a low fat-diet increase fat sensitivity thereby allowing people to get the same pleasure out of low-fat foods?

4) Can we develop artificial compounds that can stimulate the fat receptors thereby mimicking a higher fat content of foods (like we do with artificial sweeteners)?

Lots of interesting questions, which may not only explain why some people derive more pleasure from fatty foods than others but also open new possibilities for the food industry to manipulate the taste of foods (hopefully to our benefit).

I’d love to hear from my readers regarding their thoughts on “tasting” fat.

AMS
Edmonton, Alberta

Over the past three days, newspapers across Canada have been publishing a three-part series on obesity by CanWest’s Sharon Kirkey.

For this mini-series, Sharon spoke to many prominent and outspoken Canadian Obesity Network members including Valerie Taylor (McMaster), Eric Doucet (Ottawa), Nikolas Christou (McGill), Robert Ross (Queens), Yoni Freedhoff (Ottawa) and researchers from the US on a wide range of subjects relevant to this topic. She also interviewed a number of people who have struggled with obesity and its many physical and psychosocial consequences.

As expected, not all experts agree on every aspect of the debate and some statements are clearly more controversial than others. Nevertheless, I would certainly view the articles as a balanced and insightful view of the true causes of the obesity epidemic and the possible solutions (or rather the barriers to solutions).

For those who missed the series, here are the links:

Part 1: The exercise myth: Physical activity plays an important role in healthy living, but it’s not enough to make you lose weight.

Part 2: The trouble with food: A look at the science and psychology of overeating.

Part 3: Fighting an epidemic: A search for the solution.

While readers may criticize that many topics relevant to the obesity discussion were not mentioned (e.g. gut bacteria, genetic programing, sleep deprivation, etc.), remember, this was a three-part not a ten-part series on this topic. 

Noticeably, the same articles appeared under different headings in different papers, in some with more controversial titles than in others (I guess the local editors wanted to add their own spin to attract readers).

Although, I believe that the articles do discuss both sides of the debate on each of the topics,  I am sure that the critics will find their pet-topic under- or mis-represented.  Indeed, I am convinced that many readers, especially those with their usual grudge and bias against obese people as well as those who have all the (simple) answers, will probably be unhappy.

I can only commend the editors of these papers (and of course Sharon) for taking on this important topic and not shying away from controversy, which I know these articles will provoke.

The more open debate we have on this subject, the better.

Appreciate views from any of my readers, who have read these articles.

AMS
Edmonton, Alberta

There is no doubt that dietitians are the health professionals most often looked to for advise on weight management.

It may therefore come as a surprise to many readers that although dietitians have vast knowledge about healthy eating and the dietary management of a wide range of diseases like diabetes, kidney disease, celiac disease and many others, most dietitians interestingly do not have specific training in treating obesity (the same can sadly be also said for the vast majority of doctors, nurses, exercise physiologists, or any other health profession you can think of).

No one is more acutely aware of this lack of expertise than the dietitians themselves, especially as they are so often called upon for dietary advise by people trying to manage their weight.

As anyone working in this field quickly recognizes (and regular readers of these pages will know this by now), eating or ingestive behaviour is only one part of the energy balance equation and even there, the many socio-psycho-biological factors that determine caloric intake are anything but simple.

I am therefore particularly pleased that the Dietitians of Canada have partnered with the Canadian Obesity Network to co-host the first pan-Canadian Learning Retreat on the Principles & Practice of Interdisciplinary Obesity Management for Dietitians, that is currently being held in Winnipeg.

The aim of the retreat is of course not to teach dietitians about counseling clients on healthy eating or even about nutritive approaches to weight losst. Rather, the retreat focusses on all of the other topics that dietitians need to know about in order to fully understand and appreciate the many factors that are essential for effective obesity management.

It is therefore not surprising that there is a lot of room on the program for the discussion of topics like weight bias, psychosocial factors, mental health, neurobiology of hunger and satiety, exercise physiology, body composition, and of course medical and surgical management of obesity.

Judging by the enthusiasm of the attendees, it appears that such a learning opportunity has been long overdue and I am certainly hopeful that events like this will help ensure that patients struggling with excess weight will have an increasing number of dietitians to turn to, who have been specifically trained in obesity management.

AMS
Winnipeg, Manitoba