Wednesday, July 23, 2014

In Memorium: Albert (Mickey) J Stunkard

Stunkard twinsAs I spend my days at the 9th Canadian Obesity Network’s Summer Bootcamp for young trainees from Canada and around the world, I was saddened to learn of the passing of Mickey Stunkard, clearly one of the biggest names in obesity research – at a healthy age of 92.

With well over 500 publications to his name, Mickey is perhaps best known for his twin studies showing that the body weight of adopted identical twins reared apart resembles each other and that of their biological parents rather than the weight of their adoptive parents.

This work helped establish the basis for much of the genetic work on obesity that followed, clearly showing that differences in body weight between two individuals are much more accounted for by their difference in genetics than by differences in their “lifestyles”.

These findings were often misused in “nature vs. nurture” debates, an issue that serious scientists have long laid to rest in light of our current understanding that the two cannot be discussed separately, simply because genes and lifestyle interact on virtually every level – from molecules, to cells, to behaviours.

Here is what one obituary had to say about Mickey:

“He surveyed obesity treatment studies in the late ’50s and found that the nation’s diet programs could claim only a 2 percent success rate. He was an early advocate for the use of bariatric surgery to induce weight loss. He also published the first modern account of binge eating in obese individuals.”

I have had to pleasure to often hear him speak at conferences.

He will be dearly remembered.

@DrSharma
Kananaskis, AB

 

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Tuesday, July 15, 2014

The Molecular Biology of Food And Mood

sharma-obesity-brainThe neuroendocrine systems that control ingestive behaviour are intimately linked to the parts of the brain that control mood.

Thus, it is increasingly evident that factors that affect energy homeostasis (diet and exercise) can have profound effects on mood while changes in mood can have significant effects on appetite and energy homeostasis.

But this relationship is far from straightforward – rather, it appears to be rather complex.

Readers interested in an overview of how these two systems interact in the brain may find a recent review by Chen Liu from the University of Texas Southwestern Medical Center, Dallas, published in Cell Metabolism of interest.

The authors review our current understanding of how mood and food are linked with particular attention to appetite, ingestive behaviour and energy homeostasis.

The article also touches on the effects of pharmacological and surgical treatments for obesity on mood.

Clearly clinicians need to be aware of the close links between these systems and draw on our current understanding of both in their counselling of patients presenting with weight gain and/or depression.

@DrSharma
Edmonton, AB

ResearchBlogging.orgLiu C, Lee S, & Elmquist JK (2014). Circuits Controlling Energy Balance and Mood: Inherently Intertwined or Just Complicated Intersections? Cell metabolism, 19 (6), 902-909 PMID: 24630814

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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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Thursday, July 10, 2014

Can Germs In Your Drinking Water Help Prevent Obesity?

sharma-obesity-tap-water1In my show I joke about how I intend to import water from the river Ganges as a new obesity treatment that I will appropriately name “RunFast”.

Jokes aside, a study by Zhongyi Chen and colleagues, published in the Journal of Clinical Investigation, shows that treating mice with genetically modified bugs delivered through their drinking water can protect them from becoming obese even when fed a high-fat diet.

To be exact, the researchers used a strain of e coli bacteria genetically engineered to produce N-acylphosphatidylethanolamines (NAPEs), which are precursors to the N-acylethanolamide (NAE) family of lipids, normally synthesized in the small intestine in response to feeding and known to reduce food intake.

As their study shows, administration of these modified bacteria in drinking water for 8 weeks dramatically lowered food intake, weight gain, body fat, insulin resistance and liver fat in mice on a high-fat diet.

These “protective effects” lasted for at least 4 weeks after removal of these bacteria from the drinking water.

In another set of experiments the researchers also showed that this strain of bacteria reduced weight gain in a genetic model of mouse obesity.

Contrary to what one may believe, this study neither supports nor refutes the idea that gut bacteria may be partly responsible for the obesity epidemic.

Rather, the study primarily shows that bacteria may be used as a delivery system for “therapeutic doses” of molecules to the intestines – in this case, resulting in the modification of appetite and metabolism.

I would not be surprised if the therapeutic use of bacteria (genetically modified or not) opens up a whole new dimension of therapeutics – not just for obesity.

@DrSharma
Edmonton, AB

ResearchBlogging.orgChen Z, Guo L, Zhang Y, L Walzem R, Pendergast JS, Printz RL, Morris LC, Matafonova E, Stien X, Kang L, Coulon D, McGuinness OP, Niswender KD, & Davies SS (2014). Incorporation of therapeutically modified bacteria into gut microbiota inhibits obesity. The Journal of clinical investigation PMID: 24960158

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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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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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