Friday, June 27, 2014

Canadians Embark on Landmark Study on Managing Childhood Obesity

sharma-obesity-kids-scale2In line with  global trends, there is considerable concern in Canada on the rising prevalence of childhood obesity.

While much work continues to focus on preventing childhood obesity, far less is known about managing it.

Now, a virtual who-is-who of pediatric obesity researchers and clinicians from across Canada have embarked on a creating the CANadian Pediatric Weight Management Registry (CANPWR), the protocol of which appears in BMC Pediatrics.

CANPWR has three primary aims:

1. To document changes in anthropometric, lifestyle, behavioural, and obesity-related co-morbidities in children enrolled in Canadian pediatric weight management programs over a three-year period;

2. To characterize the individual-, family-, and program-level determinants of change in anthropometric and obesity-related co-morbidities;

3. To examine the individual-, family-, and program-level determinants of program attrition.

This prospective cohort, multi-centre study will include 1,600 children (2 – 17 years old with a BMI >=85th percentile) enrolled in eight Canadian pediatric weight management centres.

Data collection will occur at presentation and 6-, 12-, 24-, and 36-months follow-up.

Although the primary study outcomes are BMI z-score and change in BMI z-score over time a number of secondary outcomes including other anthropometric (e.g., height, waist circumference,), cardiometabolic (e.g., blood pressure, lipid profile, glycemia), lifestyle (e.g., dietary intake, physical activity, sedentary activity), and psychosocial (e.g., health-related quality of life) variables will also be assessed.

The researchers will also examine potential determinants of change and program attrition including individual-, family-, and program-level variables.

I am certain that the findings will be of considerable interest not just in terms of helping us better understand exactly how childhood obesity is being effectively managed in Canada (or not) but also provide important insights for planning future obesity management services for kids with overweight and obesity.

@DrSharma
Vancouver, BC

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Thursday, June 26, 2014

Guidelines for Managing Overweight and Obesity in Adults

the obesity societyRegular readers may recall a previous post on guidelines on obesity management released by The Obesity Society (TOS) together with other organisations, including the American Heart Association and the American College of Cardiology, at Obesity Week in Atlanta last year (2013).

The bottom line, as I have blogged before, was the revelation of just how little we actually know about obesity.

For what it is worth, the complete guidelines are now published as a supplement to its July issue of the Obesity journal (Guidelines (2013) for Managing Overweight and Obesity in Adults: Full Report).

According to The Obesity Society’s press release,

TOS is investing in the improved treatment of obesity by making the full guidelines available in print so they can serve as a go-to resource for health practitioners around the world. Whether you are a physician, nurse, nutritionist or fitness trainer, every professional interacting with individuals with obesity can find value in this insightful treatment guide.

No doubt, a tremendous amount of work went into developing these guidelines – whether they will substantially change practice remains to be seen.

@DrSharma
Vancouver, BC

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Tuesday, June 24, 2014

Time To Go Nuts About Nuts?

sharma-obesity-nutsNuts are reportedly chock full of all kinds of nutrients and are probably among the healthiest of snacks. However, they are also among the most calorie-dense foods – a small handful of nuts (~30 g) can easily add up to 150-200 cals.

So, do high consumers of nuts run the risk of weight gain?

This issue is discussed in depth by Sze Yen Tan and colleagues in a paper published in the American Journal of Clinical Nutrition, in which they review the effects of nuts on appetite, food intake, metabolism, and body weight.

While eating nuts may not exactly lead to weight loss, most studies find that consumption of “extra” calories as nuts leads to substantially less weight gain than may be expected based on their caloric content.

Their review reflect a number of ways in which nuts may have this effect:

Effect on hunger and appetite:

“…nut ingestion suppresses hunger and desire to eat and promotes fullness. These sensations may aid dietary compensation that offsets much of the energy contributed by nuts. However, strong compensation can also occur independently of reported appetitive effects. This may reflect imprecision in appetite measurement or a truly independent uncharacterized mechanism.”

Mastication (chewing):

“Nuts require considerable oral processing effort and this may, in part, account for the often-noted less-than-predicted effect of their consumption on body weight. The mechanical act of chewing reportedly generates satiation signals through cognitive, neural, endocrine, and physical (eg, gastric emptying) mechanisms; augments cephalic phase responses linked to appetite; influences digestion efficiency; modestly increases energy expenditure; and elicits dietary compensation.”

Nutrient absorption:

“A number of studies have evaluated the efficiency of energy absorption from ground and tree nuts through feeding trials. All showed substantive increases in fecal fat loss with nut consumption, although the values ranged widely from ∼5% to >20%”

Energy expenditure:

“Collectively, there is some evidence that nut consumption increases thermogenesis, but the data are not robust and there is no clear mechanism. One possibility is that the lipid from nuts is absorbed over a prolonged period of time, leading to a small but sustained source of substrate that fuels thermogenesis and could appear as an increase in REE.”

Fat metabolism:

“It has been proposed that nut consumption elevates fat oxidation and preferentially reduces body fat mass, especially in the viscera. These actions are attributed to their high unsaturated fat content….Human studies incorporating different nuts into the diet at realistic doses are needed to determine the effect of nut consumption on body composition.”

With regard to impact on body weight, the authors reach the following conclusions:

Adding nuts to habitual diets:

“Although there are reports of small, but significant increases in body weight with nut consumption, the preponderance of evidence indicates that under controlled or free-living situations, nut consumption does not promote weight gain.”

Eating nuts in calorie-restricted diets:

“The inclusion of nuts in energy-restriction regimens does not impede weight loss. In several trials in which nuts did not augment weight loss, there was a reduction in cardiovascular disease risk indexes in the nut-consuming groups, suggesting that such benefits derive from properties of the nuts rather than just weight change.”

Eating nuts in weight maintenance:

“Several studies assessing the role of nut consumption in weight-maintenance programs have noted a decrease in body weight from baseline. Whether this is due to a greater thermic effect of food or REE effect of the nuts compared with the foods they displaced in the diet has not been established. Nevertheless, current data indicate that the inclusion of nuts in a weight-maintenance program will not lead to weight gain and may aid weight loss.”

Thus, in summary, the authors conclude that,

“…evidence indicates that they pose little challenge to and may even aid weight management. This is attributable to the strong dietary compensation effects they elicit, inefficiency in the absorption of the energy they provide, and possibly an elevation of energy expenditure and fat oxidation.”

As a general caveat to all of these data, it needs to be noted that results varied widely depending on the types of nuts and how exactly these nuts were consumed (e.g. as snacks or added to meals – the former often being more favourable than the latter).

Also, many of the studies had relatively small number of participants and were of rather short duration.

Nevertheless, it does appear that going nuts about nuts may not be quite as detrimental to your weight as their energy content would suggest.

@DrSharma
Toronto, ON

ResearchBlogging.orgTan SY, Dhillon J, & Mattes RD (2014). A review of the effects of nuts on appetite, food intake, metabolism, and body weight. The American journal of clinical nutrition, 100 (Supplement 1) PMID: 24920033

 

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Monday, June 23, 2014

Does More Energy In And Out Make It Easier To Maintain Energy Balance?

sharma-obesity-caloric_balance_scaleFrom every thing we know about obesity, the simplistic model of energy-in-energy-out (or Eat-Less-Move-More) approach to managing weight has not led us to any meaningful advances in obesity management. The number of people who can successfully manage their weight by this approach in the long-term is so minuscule, that every “success story” is considered “newsworthy”.

Now, a provocative paper by Gregory Hand and Steven Blair, published in US Endocrinology, suggests that what matters for good health is the amount of energy flowing through the system rather than the state of energy balance.

Thus,

“Recent findings suggest that a high energy flux, maintained by increasing energy expenditure, can improve an individual’s metabolic profile without changing weight.”

This, essentially, is a fancy way of saying, that simply moving more calories through your body by burning more calories (even if you instantly eat them back) benefits the organism irrespective of any impact this may have on body weight – or that exercise is good for you even if you do not lose weight.
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Anyone familiar with Steven Blair’s work (fat and fit is better than skinny and unfit) – will recognize the theme – but couching it in a concept of energy flux is a novel and interesting spin to this idea.

Apart from providing a theoretical model for how exercise may benefit you even if you don’t lose any weight doing it, the model may also have implications for weight management.

Thus,

“The significance of the model of energy regulation is twofold: First, the model suggests that energy balance, and maintaining a stable weight is more easily achieved at a high energy flux. Second, a high energy flux can be achieved by matching a high energy intake with equivalent high energy expenditure, or by increasing energy stores (gaining weight). Of note is that these two characteristics of the model suggest that the biological system was designed to maintain a high energy flux, and increasing energy stores is a quite viable mechanism to achieve this level of energetics. An extensive body of research indicates that multiple and redundant mechanisms regulate the ‘drive’ for energy intake. The high energy flux is attained by matching the intake with expenditure and/or a change in energy storage. Weight gain is consistent with high energy flux combined with low energy expenditure, and it follows that attempting to achieve energy balance at a low energy flux (sedentary behavior combined with food restriction) is not a long-term strategy for weight maintenance.”

The biological question that pops into my mind of course is as to how exactly the body would sense this “flux”. While it is easy to see how the body would sense energy stores (e.g. through hormonal signals such as leptin), it is not clear how the body would monitor flux (after all, to regulate something, it needs to be measured).

This is not something that the authors delve into, thus leaving a somewhat unsatisfying gap in what otherwise makes for an interesting hypothesis.

@DrSharma
Toronto, ON

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Friday, June 20, 2014

Your Body Thinks Obesity Is A Disease

sharma-obesity-adipose-tissue-macrophageYesterday, the 4th National Obesity Student Summit (#COSM2014) featured a debate on the issue of whether or not obesity should be considered a disease.

Personally, I am not a friend of such “debates”, as the proponents are forced to take rather one-sided positions that may not reflect their own more balanced and nuanced opinions.

Nevertheless, the four participants in this “structured” debate, Drs. Sharon Kirkpatrick and Samantha Meyer on the “con” team and Drs. John Mielke and Russell Tupling on the “pro” team (all from the University of Waterloo) valiantly defended their assigned positions.

While the arguments on the “con” side suggested that “medicalising” obesity would detract attention from a greater focus prevention while cementing the status quo and feeding into the arms of the medical-industrial complex, the “pro” side argued for better access to treatments (which should not hinder efforts at prevention).

But a most interesting view on this was presented by Tupling, who suggested that we only have to look as far as the body’s own response to excess body fat (specifically visceral fat) to determine whether or not obesity is a disease.

As he pointed out, the body’s own immunological pro-inflammatory response to excess body fat, a generic biological response that the body uses to deal with other “diseases” (whether acute or chronic) should establish that the body clearly views this condition as a disease.

Of course, as readers are well aware, this may not always be the case – in fact, the state of “healthy obesity” is characterized by this lack of immunological response both locally within the fat tissue as well as systemically.

Obviously, it will be of interest to figure out why some bodies respond to obesity as a disease and others don’t – but from this perspective, the vast majority of people with excess weight are in a “diseased” state – at least if you asked their bodies.

While this is a very biological argument for the case – it is indeed a very insightful one: it is not the existence of excess body fat that defines the “disease” rather, how the body responds to this “excess” is what makes you sick.

As readers, are well aware, there are several other arguments (including ethical and utilitarian considerations) that favour the growing consensus on viewing obesity as a disease.

Of course,  calling obesity a disease should not detract us from prevention efforts, but, as I often point out, just because be treat diabetes or cancer as diseases, does not mean that we do not make efforts to prevent them.

If calling obesity a disease increases resources towards better dealing with this problem and helps take away some of the shame and blame – so be it.

@DrSharma
Waterloo, Ontario

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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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