Hindsight: Metabolic Rate in Obesity Hypertension
In 2000, one of my doctoral students, Iris Kunz examined the relationship between resting metabolic rate and obesity related hypertension in human volunteers. Based on our longstanding interest in the sympathetic nervous system, we hypothesized that increased sympathetic the increased sympathetic activity commonly associated with hypertension in obese subjects, would result in higher resting metabolic rates. For this study we used indirect calorimetry to determine basal substrate use and metabolic rate in 166 normotensive and hypertensive normal weight or obese subjects. It turned out that 42 of the 91 hypertensive subjects were on beta-adrenergic blockers and had significantly reduced metabolic rates – these were excluded from the subsequent analyses. In the remaining subjects, we found an almost 10% higher metabolic rate in the hypertensive compared to the normotensive subjects. This higher rate was associated with higher levels of plasma catecholamines and leptin, as well as an increased insulin response to an oral glucose load. In our paper published in HYPERTENSION, we discussed these findings a supporting our hypothesis that the elevated sympathetic activity seen in obese hypertensive subjects would be associated with an increased metabolic rate. Although these findings may not have any immediate clinical implications, they do provide some insight into how neurogenic and metabolic factors may play a role in obesity hypertension. Certainly, it is always comforting when actual findings are in line with what we would have predicted based on what we know about obesity, sympathetic activity, and metabolic rate. According to Google Scholar, this paper has been cited 46 times.
Interdisciplinary Bariatric Care
Yesterday, I gave a key note talk on why bariatric surgery should not be seen as a ‘quick fix’ for obesity at the 5th Annual Obesity Symposium hosted by the European Surgical Institute in Norderstedt (just outside Hamburg). I also participated in an interdisciplinary panel discussion of six interesting cases that were presented to us for comment. While all panelist agreed that surgical treatment is currently the most effective treatment for patients with severe obesity, several of us were also quick to point out that this does not make obesity a surgical disease. In fact, there was general agreement among the panelists that this is a condition that is best managed in a multidisciplinary setting which includes internists and psychiatrists as well as nurses and other allied health care providers. As one panelist pointed out, while the surgery may help the patient sustain weight loss, the many medical and psychosocial problems that patients often face before and after surgery need to be addressed in order for them to get the maximum benefit from the procedure. It was interesting, but not surprising, to note that surgeons from all three countries (Germany, Switzerland and Austria) universally complained about the fact that they often had nowhere to send their operated patients for follow-up leaving them with the burden of trying to provide what little support they could after surgery. While the surgeons fully realized that the underlying problems in cases where patients struggled or faced complications were seldom ‘surgical’, they often found it difficult to direct these patients to appropriate providers better qualified to deal with the psychosocial or mental issues that caused these problems. Thus, surgeons reported often finding themselves reoperating on ‘unsuccessful’ patients in the hope that a more drastic operation would fix the problem (which in most cases it didn’t). This speaks to the importance of ensuring that any increase in bariatric surgical capacity must be matched by an increase in capacity of other providers to assist in the care of these often complex patients. Unfortunately, in many setting, such services are either not available or significantly under funded, often leaving patients abandoned and struggling. This issue is certainly by no means unique to these countries. Rather it appears to be rather universal experience that, while attracting surgeons to do the operations is rather straightforward, finding competent physicians willing to work in this field is far more difficult. AMS London,… Read More »
Childhood Obesity: Role of Parents and Parenting
There are no doubt rare cases of childhood obesity that occur due to genetic, psychological, or other biological factors that are specific to just the kid and do not apply to anyone else in the family. In the vast majority of cases, however, familial or other factors resulting in childhood excess weight gain, affect more than just the kid. An excellent review and Scientific Statement on the role of targeting parents as ‘agents of change’ for treating obese children was just released by the American Heart Association and published in CIRCULATION. The paper evaluates the strength of evidence that particular parenting strategies can leverage behavior change and reduce positive energy balance in obese youth. As may be expected, the evidence is inconsistent. “For example, only 17% of the intervention studies reported differential improvements in child overweight as a function of parental involvement in treatment. On the other hand, greater parental adherence with core behavior change strategies predicted better child weight outcomes after 2 and 5 years in some studies.” The authors identify a number of important research gaps, including the assessment of refined parenting phenotypes, cultural tailoring of interventions, examination of family relationships, and incorporation of new technologies. Interestingly, the release of this statement coincides with the publication of a paper by Laurie Miller Brotman and colleagues from the New York University School of Medicine in the journal PEDIATRICS, suggesting that interventions aimed at generally improving parenting skills may reduce obesity risk in high-risk minority youth. The study included 186 minority youth at risk for behavior problems who enrolled in long-term follow-up studies after random assignment to family intervention or control condition at age 4. Follow-up Study 1 included 40 girls at familial risk for behavior problems; Follow-up Study 2 included 146 boys and girls at risk for behavior problems based on teacher ratings. Importantly, the family intervention aimed to promote effective parenting and prevent behavior problems during early childhood and did not not focus on physical health or attempt to specifically modify diets or physical activity. After five years (Study 1) and 3 years (Study 2), the kids randomized to intervention had significantly lower BMI compared to controls with lower rates of obesity (BMI ≥95th percentile) among intervention girls and boys. These changes in body weight were associated with improvements in physical and sedentary activity, blood pressure, and diet. Thus, as the authors point out, simply improving parenting skills… Read More »
Do Heart Hormones Regulate Brown Fat?
As some readers may be aware, the heart, apart from simply pumping blood through our arteries, also secretes hormones called natriuretic peptides, which play an important role in regulating blood volume. Natriuretic peptide levels tend to be markedly increased in patients with heart failure. Now, a study by Marica Bordicchiia and colleagues, from the Sanford-Burnham Medical Research Institute, Orlando, Florida, published in the Journal of Clinical Investigation suggests that this hormone may also markedly affect the formation and function of brown fat. As readers will recall, brown fat is an important determinant of caloric expenditure – a couple of ounces of this tissue can account for almost 20% of resting metabolic rate and therefore, not having enough of this tissue has been implicated as a risk factor for weight gain. In their study, Bordicchia and colleagues not only show that cultured human adipocytes exposed to atrial NP (ANP) and ventricular NP (BNP) not only grew more mitochondria but also showed increased expression of uncoupling protein (UCP1) with increased uncoupled and total respiration. Additional studies in mice showed that infusion of BNP into mice robustly increased UCP1 expression in both white and brown fat, with corresponding elevation of respiration and energy expenditure. Together these findings suggest an unrecognized role of there heart hormones in the regulation of caloric expenditure by promoting the “browning” of white adipocytes to increase energy expenditure. The authors point out that their discovery may point to a new explanation for the weight loss often associated with severe heart failure often referred to as ‘cardiac cachexia’. In addition, as brown fat represents a natural ‘defence mechanism’ to obesity, it will be interesting to see how this hormonal pathway can perhaps be harnessed to prevent or treat obesity in humans. AMS Philadelphia, PA Bordicchia M, Liu D, Amri EZ, Ailhaud G, Dessì-Fulgheri P, Zhang C, Takahashi N, Sarzani R, & Collins S (2012). Cardiac natriuretic peptides act via p38 MAPK to induce the brown fat thermogenic program in mouse and human adipocytes. The Journal of clinical investigation PMID: 22307324 .
Why Are There No Obese Men in Canada and Why Does Nobody Care?
OK, actually there are plenty of obese men in Canada – in fact slightly more than obese women. In addition, the health risks of obese men are somewhat higher than those of obese women, if only because men tend to accumulate visceral and abdominal fat rather than deposit the excess weight on their hips and thighs. As faithful readers may recall, I have previously discussed the differences between men and women when it comes to how they perceive their excess weight. Thus, not surprisingly, women make up well over 80% of participants in most weight loss programs, even in those that provide medical or surgical obesity management. This topic will now be the theme of a Café Scientifique (Is Canada ignoring obesity in men?), to be held on Wednesday, February 15, 2012, 5:00 p.m. to 7:00 p.m. at Edmonton City Hall. The event, co-sponsored by the Canadian Institute of Health Research Institute of Gender and Health and the Canadian Obesity Network, will try to find answers to questions like the following: If more men than women live with excess weight in Canada, why, when we hear statistics about rising obesity levels these gender trends are often overlooked. Why are men affected by obesity more than women, and why do we talk about it less? Is biology to blame? As a society, are we more willing to accept obesity in men? And are they getting the help they need? Join moderator Mark Connolly of CBC News Edmonton and some of Canada’s top researchers and health professionals, together with a patient sharing his experience, to discuss what’s driving the issue, and what can be done about it. Featured speakers: Dr. Kim Raine, Professor, School of Public Health, University of Alberta Dr. Daniel Birch, Professor, Department of Surgery, University of Alberta J. Jacque E. Lovely, Clinical Nurse Specialist, Alberta Health Services Provincial Bariatric Resource Team Marty Enokson, Patient and advocate This event is free, but space is limited. Please RSVP: cook@obesitynetwork.ca AMS Philadelphia, PA
Why Banning Sugar Will Not Solve Obesity
Last week, the media erupted in reports and commentaries prompted by an article by Robert Lustig and colleagues front the University of California, published in the journal NATURE, calling on governments to regulate sugar in a fashion akin to alcohol. Although the media referred to this piece as a ‘new study’, the article did not actually provide any new data – it was merely an ‘opinion piece’ suggesting legislative approaches to the ill-effects of eating too much sugar. Presented as a possible solution to the obesity epidemic, the jist of the arguments more or less were as follows: worldwide sugar consumption has increased, sugar is toxic and addictive and, therefore, regulating sugar like alcohol or tobacco (including taxation and limiting access to individuals below the age of 17), would reduce obesity and prevent metabolic syndrome. In a number of media interviews, I took issue both with the proposal to tax and ban sugar as well as the rather simplistic causal linking of sugar to the obesity epidemic. Here is why: 1) While there is no doubt that overconsumption of sugar (like consuming too much salt (not sodium!), trans-fats, alcohol, or perhaps processed foods in general) may well promote ill health, these links may be far less robust or scientifically proven than the article suggests. More importantly, there is very little evidence from high-quality intervention studies (outside of the rather artificial setting of a clinical trial) that the proposed population measures (namely attempting to restrict sugar consumption by banning or taxing it) would have the desired effect on obesity or anything else – if there are such examples, the article certainly fails to mention them. 2) As any reader of these pages will also realize, obesity is a multifactorial complex condition driven by a myriad of socioeconomic, psychological, and biological factors – some of which do indeed make many of us prone to ‘overconsume’ salt, sugar, fats, and perhaps alcohol or illicit drugs. In the case of sugar, the article unfortunately fails to seriously delve into what exactly these socioeconomic, psychological, or biological drivers to consume more sugar may be (beyond simply suggesting that sugar is cheap, omnipresent and ‘addictive’). Unfortunately, by reducing the solution to the obesity epidemic to simply a matter of banning and taxing sugar, the article not only reinforces the widely held stereotype that obese people are obese simply because they eat too much (in this case… Read More »
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