Monday, August 18, 2014

Hormonal Responses to Food Intake Begin in Your Mouth

ChewOnThisLogoIn my current show at the 33rd Edmonton International Fringe Theatre Festival, I joke about the importance of chewing your food. This has classically been noted to be of importance to allow the enzymes in saliva to begin the process of digestion.

However, now a fascinating study by Yong Zhu and colleagues from Iowa State University, published in Physiology and Behaviour shows that chewing prompts hormonal changes that vary based on the composition of the food.

In their study, ten healthy males volunteers underwent a sham-feeding experiments (you chew but do not swallow your food) after an overnight fast with 3-min chewing of water, high-fat (nuts), high-carbohydrate (cereal) or high-protein (cheese) food provided in a randomized order (on four separate occasions).

While plasma glucose levels increased slightly and plasma lipids decreased slightly after all test foods, the high-carbohydrate food elicited significantly higher insulin, and the high-protein food resulted in higher ghrelin compared to other test sessions.

The authors attribute these changes in part to neuronal signals transmitted through the vagal nerve, which can for e.g. stimulate glucagon release, thereby explaining the observed increase in plasma glucose levels after all foods.

This study shows that short-term oral exposure to different foods can result in metabolic and hormonal changes that are partly dependent on diet composition.

If nothing else, this study points to the fact that chewing is not simply about mechanically preparing food for swallowing – it is far more a process that puts the organism into a nutritive state with distinct metabolic and hormonal changes.

Chew your food!

@DrSharma
Edmonton, AB

ResearchBlogging.orgZhu Y, Hsu WH, & Hollis JH (2014). Modified sham feeding of foods with different macronutrient compositions differentially influences cephalic change of insulin, ghrelin, and NMR-based metabolomic profiles. Physiology & behavior, 135, 135-42 PMID: 24952264

 

.

VN:F [1.9.22_1171]
Rating: 0.0/10 (0 votes cast)
VN:F [1.9.22_1171]
Rating: 0 (from 0 votes)


Tuesday, August 5, 2014

Evidence for Benefit of Psychological Intervention Before Bariatric Surgery

sharma-obesity-psychotheralyCurrent bariatric surgery guidelines recommend psychological assessment prior to undergoing bariatric surgery. In some centres, this assessment is less than rigorous and, in cases where patients have been denied surgery because of psychological findings, providers have been accused of bias and discrimination.

Nevertheless, most people working in the field, tend to agree that, when present, emotional drivers of weight gain are best dealt with before rather than after surgery.

Now, a randomised controlled trial by Hege Gade and colleagues from Tromsø, Norway, published in The Journal of Obesity, shows the benefit of 10 weeks or cognitive behavioural intervention in patients seeking bariatric surgery, who present with dysfunctional eating behaviours.

A total of 98 (70% females) patients with a mean age of 43 years and BMI of 43.5 kg/m2 were randomly assigned to 10 weeks of weekly CBT-group therapy or usual nutritional support and education (controls).

The CBT sessions were included learning to recognize triggers of dysfunctional eating, identifying associated cognitions and emotions, initiating plans for change, and home-work tasks between sessions.

Compared the controls, the CBT-group showed a remarkable improvement in eating behaviours as well as improvements in depression and anxiety scores at the end of the intervention. They also experienced some modest weight loss (~3 kg).

While these benefits speak for the effectiveness of CBT, the study does not provide any outcome data post-surgery to show that these patients do better after surgery than the controls – that, I believe, remains to be shown.

Nevertheless, common sense suggests that dysfunctional (emotional) eating (when present) is perhaps best dealt with prior to surgery than after the procedure.

@DrSharma
Edmonton, AB

 

VN:F [1.9.22_1171]
Rating: 10.0/10 (1 vote cast)
VN:F [1.9.22_1171]
Rating: 0 (from 0 votes)


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

 

VN:F [1.9.22_1171]
Rating: 10.0/10 (2 votes cast)
VN:F [1.9.22_1171]
Rating: 0 (from 2 votes)


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

.

 

VN:F [1.9.22_1171]
Rating: 10.0/10 (1 vote cast)
VN:F [1.9.22_1171]
Rating: 0 (from 0 votes)


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

.

VN:F [1.9.22_1171]
Rating: 7.0/10 (2 votes cast)
VN:F [1.9.22_1171]
Rating: +1 (from 1 vote)

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

» More news articles...

Publications
  • No items
  • » Browse and download more journal publications...

    Watch Dr. Sharma in the News!

    Dr. Sharma - NEWS Videos

    Listen to Dr. Sharma!

    Dr. Sharma - on CBC.ca

    Watch Dr. Sharma on Listen Up


  • Subscribe via Email

    Enter your email address:

    Delivered by FeedBurner




  • Arya Mitra Sharma
  • Disclaimer

    Postings on this blog represent the personal views of Dr. Arya M. Sharma. They are not representative of or endorsed by Alberta Health Services or the Weight Wise Program.
  • Archives

     

  • RSS Weighty Matters

  • Click for related posts

  • Disclaimer

    Medical information and privacy
    Any medical discussion on this page is intended to be of a general nature only. This page is not designed to give specific medical advice. If you have a medical problem you should consult your own physician for advice specific to your own situation.


  • Meta

  • Obesity Links

  • If you have benefitted from the information on this site, please take a minute to donate to its maintenance.

  • Home | News | KOL | Media | Publications | Trainees | About
    Copyright 2008–2014 Dr. Arya Sharma, All rights reserved.
    Blog Widget by LinkWithin