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BMI Versus Fitness In Hypertension Risk

sharma-obesity-blood-pressureA higher BMI has long been associated with increased risk of hypertension (and there are many important physiological mechanisms at play to account for this relationship).

Now a study by Crump and colleagues published in JAMA Intern Medicine suggests that some of this risk may be mitigated by increased physical fitness.

The cohort study involving over 1.5 million Swedish young men in Sweden, who underwent standardized aerobic capacity, muscular strength, and BMI measurements obtained at a military conscription examination and were followed for up to 40 years.

Almost 100,000 men went on to develop hypertension, whereby both high BMI and low aerobic capacity (but not muscular strength) were associated with increased risk of hypertension, independent of family history or socioeconomic factors.

A combination of high BMI (overweight or obese vs normal) and low aerobic capacity (lowest vs highest tertile) was associated with the highest risk of hypertension.

The association with aerobic fitness was apparent at every level of BMI.

Form this study the authors conclude that high BMI and low aerobic capacity in late adolescence are associated with higher risk of hypertension in adulthood.

Although one must also be cautious in assuming causality with regard to associations found in such studies, the observations are certainly compatible with the notion that increased cardiorespiratory fitness may well mitigate some of the impact of increased BMI on hypertension risk.

@DrSharma
Edmonton, AB

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CON Co-Hosts the International Congress on Obesity in Vancouver

ICO 2015 CoutinhoAs Canada’s national representative in the World Obesity Federation (formerly IASO), the Canadian Obesity Network is proud to co-host the 13th International Congress on Obesity in Vancouver, 1-4 May 2016.

The comprehensive scientific program will span 6 topic areas:

Track 1: From genes to cells

  • For example: genetics, metagenomics, epigenetics, regulation of mRNA and non–coding RNA, inflammation, lipids, mitochondria and cellular organelles, stem cells, signal transduction, white, brite and brown adipocytes

Track 2: From cells to integrative biology

  • For example: neurobiology, appetite and feeding, energy balance, thermogenesis, inflammation and immunity, adipokines, hormones, circadian rhythms, crosstalk, nutrient sensing, signal transduction, tissue plasticity, fetal programming, metabolism, gut microbiome

Track 3: Determinants, assessments and consequences

  • For example: assessment and measurement issues, nutrition, physical activity, modifiable risk behaviours, sleep, DoHAD, gut microbiome, Healthy obese, gender differences, biomarkers, body composition, fat distribution, diabetes, cancer, NAFLD, OSA, cardiovascular disease, osteoarthritis, mental health, stigma

Track 4: Clinical management

  • For example: diet, exercise, behaviour therapies, psychology, sleep, VLEDs, pharmacotherapy, multidisciplinary therapy, bariatric surgery, new devices, e-technology, biomarkers, cost effectiveness, health services delivery, equity, personalised medicine

Track 5: Populations and population health

  • For example: equity, pre natal and early nutrition, epidemiology, inequalities, marketing, workplace, school, role of industry, social determinants, population assessments, regional and ethnic differences, built environment, food environment, economics

Track 6: Actions, interventions and policies

  • For example: health promotion, primary prevention, interventions in different settings, health systems and services, e-technology, marketing, economics (pricing, taxation, distribution, subsidy), environmental issues, government actions, stakeholder and industry issues, ethical issues

Early-bird registration is now open – click here

Abstract submission deadline is November 30, 2015 – click here

For more information including sponsorship and exhibiting at ICO 2016 – click here

I look forward to welcoming you to Vancouver next year.

@DrSharma
Toronto, ON

 

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Is the Metabolically Healthy Obesity Phenotype Irrelevant for Public Health?

sharma-obesity-public-opinionAnyone who has closely followed my writings on this topic will know by now that health for a given individual cannot be measured by simply stepping on a scale (or for that matter using a measuring tape).

There are indeed individuals who appear rather healthy even at BMI levels considered to be well into the obesity range (just how many depends on your definition of “healthy”).

In an article and commentary that appears in the American Journal of Epidemiology, Juan Pablo Rey-López and colleagues from the School for Policy Studies, University of Bristol,UK, argue that the notion of “metabolically healthy obesity” (MHO), if anything is distracting and even counterproductive to public health efforts to prevent obesity.

They argue that,

“the MHO phenotype is not benign and as such has very limited relevance as a public health target.”

Throughout the article, the authors indeed make the oft-heard arguments for a population wide approach based on the notion that even a small left-shift in the weight distribution curve (as popularized by Geoffrey Rose) can have a potentially large influence on the population burden of excess weight.

This is not something anyone would argue with – at least at a population level and when the issue is prevention.

Unfortunately, Rey-López and colleagues then fall into the trap of pooh-poohing the research efforts around better trying to understand exactly why there is such a variation in how excess weight may (or may not) affect an individual’s health.

“More efforts must be allocated to reducing the distal and actual causal agents that lead to weight gain, instead of the current disproportionate scientific interest in the biological processes that explain the heterogeneity of obesity.”

Furthermore, they argue against further investments into obesity treatments:

“Nevertheless, it should be openly recognized that further investments in this predominantly individual approach will not reverse the obesity epidemic, because 1) medical therapies or dramatic lifestyle changes do not modify the distal causes of obesity (i.e., modern processed food and the built environment) and 2) individualized lifestyle modifications are commonly unsuccessful and inaccessible.

The two facts that are largely ignored in this discussion are 1) that efforts at prevention (no matter how effective) are not helping the millions of people already living with this problem and 2) trying to find better treatments by learning more about the biology of this condition is exactly how we have found treatments for a host of other conditions ranging from diabetes to hypercholesterolemia and that these treatments have indeed allowed millions of people with these conditions to live productive and meaningful lives.

Personally, I find that the line of argument presented by the authors reeks of discrimination against people living with this problem. Thus, I cannot help but think that the authors consider people with obesity a “lost cause” not worthy of the investment into finding or providing better treatments.

Whether or not the discussions about MHO will help advance the field or not is certainly debatable.

Wether pitching prevention against treatment has the potential to actually harm people living with this problem is not.

@DrSharma
Edmonton, AB

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Risks Of Severe Obesity In Children And Young Adults

smaller_active_kids4972Yes, body fat is not a measure of health and it is possible to be healthy across a wide range of body weights. However, this may become harder and harder, the more weight you gain.

Thus, a study by Asheley Skinner and colleagues, published in the New England Journal of Medicine, shows that increased cardiometabolic risk is tightly linked with severe obesity both in children and young adults.

The study looks at cross-sectional data from overweight or obese children and young adults (3-19 yrs) who were included in the US National Health and Nutrition Examination Survey (NHANES) from 1999 through 2012.

Among 8579 children and young adults with a body-mass index at the 85th percentile or higher (according to the Centers for Disease Control and Prevention growth charts), 46.9% were overweight, 36.4% had class I obesity, 11.9% had class II obesity, and 4.8% had class III obesity.

Overall, for a given weight, males tended to have higher cardiometabolic risk than females.

Even after controlling for age, race or ethnic group, more severe obesity maps more likely to be associated with low HDL cholesterol level, high systolic and diastolic blood pressures, and high triglyceride and glycated hemoglobin levels.

Importantly, while this relationship was constantly present in males, the there were fewer significant differences in these variables according to weight category among female participants, suggesting that for a given body weight, girls were less likely to be at cardiometabolic risk compared to boys.

Thus, while body weight (or body fat) may not be a precise measure of individual health, the risk for having one or more cardiometabolic risk factor increases substantially with increasing severity of obesity.

However, it is also important to note that even in kids and youth with class III obesity, 70% of participants had normal lipids and about 90% of participants did not have elevated blood pressure or glycated hemoglobin.

This points to the fact that for a given body weight there is indeed wide variability in whether or not someone actually has cardiometabolic risk factors.

Thus, whether or not it makes sense to target every kid that presents with an elevated BMI for intervention, remains to be shown – most likely such an approach would probably not be cost-effective.

As in adults, it seems that interventions in kids are probably best targeted by global risk rather than simply by numbers on a scale.

@DrSharma
Edmonton, AB

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What Are The Health Benefits of Intentional Weight Loss?

sharma-obesity-weight-gainTo conclude this brief series on our new exhaustive review of the putative health benefits of long-term weight-loss maintenance, published in Annual Reviews of Nutrition, here is the summary paragraph of our findings:

“Obesity is well recognized as a risk factor for a wide range of health issues affecting virtually every organ system. There is now considerable evidence that intentional weight loss is associated with clinically relevant benefits for the majority of these health issues. However, the degree of weight loss that must be achieved and sustained to reap these benefits varies widely between comorbidities. Downsides of weight loss that is too rapid and/or extreme may occur, as in the increased risk of gallbladder disease, the presence of excess residual skin, or deterioration in liver histology. Uncertainty also remains about the potential benefit or harm of intentional weight loss on patients presenting with some chronic diseases and on overall mortality. Clearly, well- controlled prospective studies are needed to better understand the natural history of obesity and the impact of weight-management interventions on morbidity, quality of life, and mortality in people living with obesity.”

The is much left to be done and answering some of these questions will become progressively easier as better treatments for obesity become available.

@DrSharma
Kananaskis

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