Arguments Against Obesity As A Disease #2: Inconsistent Relationship Between Body Fat And Health
Yesterday, in my brief series on the pros and cons of calling obesity a chronic disease, I addressed the issue of BMI as a poor definition of obesity (understood here as “abnormal or excess body fat that affects health”). Another common argument I hear from those who do not support the notion of obesity as a chronic disease, is that there is an inconsistent relationship between body fat and health. This is no doubt the case. Indeed, whether or not your body fat affects your health depends on a range of factors – from your genetic predisposition to certain “complications” to the “nature” of your body fat, factors that cannot be captured or assessed by simply stepping on a scale. Often, this variability in the relationship between excess body fat and its impact on health, is used to argue against a “causal relationship” between the two. This argument is often presented along the lines of, “If obesity is a disease, how come I don’t have diabetes?”. Where the direct impact of excess body fat on health should be evident, is when the amount of excess fat poses a direct “mechanical” problem that impedes physical functioning. This impact, however, is likely to vary from one person to the next. A good example of this, is obstructive sleep apnea, where an increase in pharyngeal fat deposition is directly and causally related to the airway obstruction. The causal relationship of pharyngeal fat and the symptoms is directly evident by improvement in symptoms following surgical removal of the excess fat (an operation that is seldom undertaken due to possible complications and redeposition of fat). There is also substantial evidence that significant weight loss (such as induced by bariatric surgery) results in a dramatic improvement in apnea/hypopnea index and sometimes even in complete resolution of the problem. Yet, not everyone with excess weight develops obstructive sleep apnea. One of the factors that explains this variation, is the anatomical dimension of the pharyngeal space, which varies significantly from one person to the next. So, just how much excess fat in the neck region results in symptoms (if any) will necessarily be highly variable. This is not an argument against the relationship between excess body fat and obstructive sleep apnea, it is just the expected variation between individuals that is evident in many diseases. Likewise, when the amount of excess fat impairs the body’s capacity to perform essential functions (from mobility… Read More »
Guest Post: Complications of Cardiac Surgery in Severe Obesity
Today’s guest post comes from Tasuku Terada, a postdoctoral research fellow with the Bariatric Care and Rehabilitation Research Group (BCRRG), a multidisciplinary research collaboration, focused on improving the care and rehabilitation outcomes of patients with obesity. Dr. Terada is an Exercise Physiologist and 2015 Canadian Obesity Network, Obesity Research Bootcamp alumni. His research interests include the role of exercise in counteracting chronic health conditions associated with obesity. Obesity is a risk factor for cardiovascular disease, and referrals for coronary artery bypass graft surgery (CABG) have increased in patients with severe obesity (body mass index: BMI ≥40 kg/m2). In our recent study published in the Journal of American Heart Association, using data from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) registry, we show that patients with severe obesity were 53% more likely to have complications within 30 days of surgery and had threefold higher risk of infection compared to patients without obesity. In addition, the median hospital stay was one day longer in patients with severe obesity compared to patients without obesity. In patients with severe obesity, those who had diabetes and experienced infection stayed 3.2 times longer days in hospital compared to patients without either condition. Taken together, these results highlight a need for attentive care in bypass patients with severe obesity. Strategies to minimize the risks of infection and efforts to ensure good glucose control for patients with diabetes may also be important for better patient care quality and to reduce the length of hospital stay. This type of information should be useful to caregivers and lead to prevention or preparation for possible adverse outcomes. This study was supported by a Partnerships for Research and Innovation in the Health System (PRIHS) award from Alberta Innovates – Health Solutions (AIHS). Tasuku Terada Edmonton, AB
Are We Seeing An Upward Shift In Healthy Weights?
I don’t like the term “healthy” weights, because we have long learnt that good health is possible across a wide range of shapes and sizes. Nevertheless, epidemiologists (and folks in health promotion) appear to like the notion that there is such a weight (at least at the population level), and often define it as the weight (or rather BMI level) where people have the longest life-expectancy. Readers of this literature may have noticed that the BMI level associated with the lowest mortality has been creeping up. Case in point, a new study by Shoaib Afzal and colleagues from Denmark, published in JAMA, that looks at the relationship between BMI and mortality in three distinct populations based cohorts. The cohorts are from the same general population enrolled at different times: the Copenhagen City Heart Study in 1976-1978 (n = 13 704) and 1991-1994 (n = 9482) and the Copenhagen General Population Study in 2003-2013 (n = 97 362). All participants were followed up to November 2014, emigration, or death, whichever came first. The key finding of this study is that over the various studies, there was a 3.3 unit increase in BMI associated with the lowest mortality when comparing the 1976-1978 cohort with that recruited in 2003-2013. Thus, The BMI value that was associated with the lowest all-cause mortality was 23.7 in the 1976-1978 cohort, 24.6 in the 1991-1994 cohort, and 27.0 in the 2003-2013 cohort. Similarly, the corresponding BMI estimates for cardiovascular mortality were 23.2, 24.0, and 26.4, respectively, and for other mortality, 24.1, 26.8, and 27.8, respectively. At a population level, these shifts are anything but spectacular! After all, a 3.3 unit increase in BMI for someone who is 5’7″ (1.7 m) is just over 20 lbs (~10 Kg). In plain language, this means that to have the same life expectancy today, of someone back in the late 70s, you’d actually have to be about 20 lbs heavier. While I am sure that these data will be welcomed by those who would argue that the whole obesity epidemic thing is overrated, I think that the data are indeed interesting for another reason. Namely, they should prompt speculation about why heavier people are living longer today than before. There are two general possible explanations for this: For one these changes may be the result of a general improvement in health status of Danes related to decreased smoking, increased physical activity or changes in social determinants of health (e.g.… Read More »
Overview of Obesity Management in Primary Care
Given the vast number of individuals who could potentially benefit from effective long-term obesity management, there is no option but to manage most of this problem in primary care settings. While this approach can be highly effective, it does require training, resources and ongoing (lifelong?) interventions (not unlike most other chronic diseases). Now a rather comprehensive paper by Soleyman and colleagues from the University of Birmingham, Alabama, published in Obesity Reviews provides an overview of obesity management in primary care. As readers are well aware, our body weight are tightly regulated by a complex neuroendocrine system and defends us agains weight loss through a multi-faceted physiological response to prevent further weight loss and restore body weight. As the authors note, “To maintain weightloss, individuals must adhere to behaviours that oppose these physiological adaptations and the other factorsfavouring weight regain. However, it is difficult for peoplewith obesity to overcome physiology with behaviour over the long term. Common reasons for weight regain include decreased caloric expenditure, decreased self-weighing frequency, increased caloric intake, increased fat intake and eating disinhibition over time.” The paper provides a succinct overview of the evidence supporting behavioural, medical and surgical obesity treatments. It also reiterates the basic principles of obesity management as outlined in the various guidelines: 1. Obesity is a chronic disease that requires long-term management. It is important to approach patients with information regarding the health implications. 2. The goal of obesity treatment is to improve the health of the patient, and it is not intended for cosmetic purposes. 3. The cornerstone of therapy is comprehensive lifestyle intervention from informed PCPs or other healthcare professionals. 4. The initial goal of therapy is a weight loss of 5–10% in most patients, as this is sufficient to ameliorate many weight-related complications. However, weight loss of ≥10% may be needed to improve certain weight-related complications, such as obstructive sleep apnoea. 5. Consideration should be given to the use of a weight-loss medication or possible bariatric surgery, as the addition of these treatment modalities to lifestyle therapy can promote greater weight loss and maintain the weight loss for a longer period of time. 6. It is important for clinicians to evaluate the patient for weight-related complications, that can be improved by weight loss, and to consider such patients for more aggressive treatment. These recommendations (with minor variations) are also very much in line with the 5As of Obesity Management framework… Read More »
Liraglutide Leads The Way To Cardiovascular Risk Reduction?
Earlier this week, Novo Nordisk, the maker of Victoza and Saxenda, announced top-line results from the LEADER trial, which investigated the cardiovascular safety of liraglutide 1.8mg over a period of up to 5 years in more than 9,000 adults with type 2 diabetes at high risk of major adverse cardiovascular events. The trial compared the addition of either liraglutide 1.8 mg or placebo to standard care and apparently met the primary endpoint of showing non-inferiority as well as demonstrating superiority, with a significant reduction in cardiovascular risk. According to the news release, liraglutide demonstrated superior reduction of major adverse cardiovascular events in the primary endpoint of the study (composite outcome of the first occurrence of cardiovascular death, non-fatal myocardial infarction or non-fatal stroke), a reduction that that was derived from all three components of the endpoint. The safety profile of liraglutide in LEADER was reported as, “generally consistent with previous liraglutide clinical studies”. While it is hard to fully interpret the study, the detailed results of which will be reported at the American Diabetes Conference in a few months, this may well be a landmark trial both for diabetes but also for obesity medications. Thus, although LEADER did not test the higher liraglutide 3 mg dose indicated for obesity, it is indeed reassuring that at least the liraglutide 1.8 mg dose indicated for diabetes, did not increase (and even decreased) the risk for cardiovascular complications. This is of importance, as readers may be well aware that the history of anti-obesity medications is plagued with drugs that raised safety concerns regarding cardiovascular events. Thus, while we await the full results of the LEADER trial, there appears hope for optimism that with liraglutide we may finally have a drug for the treatment of obesity that has a favourable cardiovascular safety profile. That would be a landmark indeed. @DrSharma Edmonton, AB Disclaimer: I have received honoraria as a consultant and speaker for Novo Nordisk
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