Obesity Weekend Roundup, February 14, 2014

As not everyone may have a chance during the week to read every post, here’s a roundup of last week’s posts: Guest Post: Everything You Must Know About Pregnancy and Weight Gain Four Fiery Facts About Losing Weight With Hot Sauce Five Sobering Facts About Ghrelin And Emotional Eating Why High-Intensity Exercise Makes You Crave Cucumbers Cn TXTng hlp U lse w8? Have a great Sunday! (or what is left of it) @DrSharma Edmonton, AB

Why High-Intensity Exercise Makes You Crave Cucumbers

There is no doubt that exercise is one of the most powerful ways to “work up an appetite”. But now, a study by Daniel Crabtree and colleagues from the University of Aberdeen, published in the American Journal of Nutrition, suggests that high-intensity exhaustive exercise may paradoxically increase the appeal of low-caloric foods. The researchers used functional magnetic resonance imaging (fMRI) to compare neural responses to visual food stimuli after intense exercise and rest in fifteen healthy male volunteers. Compared to the rest situation, intense exercise significantly suppressed subjective appetite responses as well as ghrelin concentrations while significantly increasing the release of peptide YY (a satiety signal). In addition, after exercise subjects showed a greater neural appetitive response (activation of the insula and putamen and reduced activity in the orbitofrontal cortex) to images of low-calorie foods (e.g. cucumbers, lettuce, etc.) but lower responses to images of high-caloric foods. Thus is appears that an acute bout of intense exercise may act as a natural appetite suppressant that tricks the brain into finding low-calorie foods more appealing than fried chicken and pizza. Unfortunately, the evidence that this approach may actually help you lose weight and keep it off is lacking. As the authors point out, “Research has shown that reductions in sensations of appetite after high-intensity exercise are short lived, and appetite responses may rebound over several hours after exercise.” My guess is that when appetite rebounds, it does so with a vengeance, explaining why exercise alone is such a poor weight loss strategy (despite all its other proven health benefits). If you have personally experienced intense cravings for cucumber after intense exercise, I’d certainly love to hear your story. @DrSharma Edmonton, AB Crabtree DR, Chambers ES, Hardwick RM, & Blannin AK (2014). The effects of high-intensity exercise on neural responses to images of food. The American journal of clinical nutrition, 99 (2), 258-67 PMID: 24305681

Obesity Weekend Roundup, Novemer 1, 2013

As not everyone may have a chance during the week to read every post, here’s a roundup of last week’s posts: When Is Your Baby Due and Other Unhelpful Weight Remarks From Health Professionals What’s The Stupidest Remark You’ve Heard From a Health Professional About Your Weight? Overstatement of Findings in Nutrition and Obesity Research? Taste Trumps Health in Food Choices? Do Ghrelin-Stabilizing Antibodies Contribute to Obesity? Have a great Sunday! (or what is left of it) @DrSharma Edmonton, AB

Post-Surgery Weight Regain: Hormonal and Metabolic Factors

In yesterday’s post, I discussed the importance of dietary factors in weight regain after bariatric surgery. In this post, I will discuss the role of hormonal and metabolic factors identified in our systematic review of post-surgical weight regain published in Obesity Surgery. It is now widely assumed that the efficacy of bariatric surgery is not solely dependent on causing a “restriction” or simply “malabsorbtion” of calories. Rather, there is now growing consensus that the key reason why bariatric surgery works is through its impact on gut hormones and neurological signals from the gut that significantly reduce hunger and/or satiety. Thus, it is not surprising that in our review we found several studies that noted a significant relationship between post-surgical levels of the “hunger hormone” ghrelin and post-surgical weight regain. Patients who experienced less weight loss or greater weight regain after sleeve gastrectomy and/or roux-en-y bypass surgery demonstrated higher fasting and post-prandial ghrelin levels. Elevated ghrelin levels were also found to correlate with a return of hunger in patients with regain. Other evidence points to the role of hypoglycaemia in promoting weight regain in some patients. Reactive hypoglycaemia after bariatric surgery may result from the rapid transit of ingested carbohydrates into the small intestine thereby generating an early and significant insulin surge which results in a reactive hypoglycaemia shortly after a meal. This would in turn prompt snacking and increased caloric ingestion resulting in weight regain. While there is currently no medical treatment to deal with ghrelin elevations, the latter problem can potentially be managed by dietary measures, including the avoidance of high-glycemic index foods. Given that there are many gut hormones that may be altered by bariatric surgery and their individual roles are still poorly understood, it is clear that we will need further studies to better understand how these factors may explain why some patients failure to lose weight after surgery or show a greater tendency for weight regain. @DrSharma Chicago, IL Karmali S, Brar B, Shi X, Sharma AM, de Gara C, & Birch DW (2013). Weight Recidivism Post-Bariatric Surgery: A Systematic Review. Obesity surgery PMID: 23996349   .

Obesity & Energetic Offerings, Aug 2, 2013

For several months now, my colleagues at the University of Alabama have been compiling a weekly list of selected obesity related articles in a list they call Obesity and Energetic Offerings. Obesity & Energetic Offerings are brought to you by the UAB NORC and Office of Energetics and compiled by David B. Allison, Michelle Bohan-Brown, Emily Dhurandhar, John Dawson, and Andrew Brown. The following is a selection of articles from this week’s list  – the link headings are theirs, not mine: Featured Perceived Hill Slant and Obesity: Perception Does Not Care about How You Feel. US pediatric population-level associations of DXA-measured percentage of body fat with four BMI metrics with cutoffs. Metformin improves healthspan and lifespan in mice. Findings Contrary to Hypotheses or Popular Ideas Cesarean mode of delivery was not clearly associated with BMI or overweight. No association between obesity and depressive disorder in adolescents at high risk for depression. RCT: A low-carbohydrate diet is as safe as Mediterranean or low-fat diets in preserving/improving renal function among moderately obese participants with or without type 2 diabetes. RCT: Acute ingestion of sugar-free red bull energy drink has no effect on upper body strength and muscular endurance in resistance trained men. RCT: Addition of personalized e-feedback in the enhanced program provided limited additional benefits compared to a standard commercial Web-based weight-loss program. RCT: n3 PUFAs Do Not Affect Adipose Tissue Inflammation in Overweight to Moderately Obese Men and Women. RCT: No effect of caffeine Intake on short bouts of physical activity or energy expenditure. RCT: No effect of conjugated linoleic acid and vitamin E on glycemic control, body composition, and inflammatory markers in overweight type 2 diabetics. Resveratrol Blunts the Positive Effects of Exercise Training on Cardiovascular Health in Aged Men. Thinness, rather than excess weight, is associated with decreased light, moderate and high intensity physical activity in Japanese pre-school children. Study vs Headlines From ConscienHealth: “Headlines That Bite: Mosquitoes Cause Childhood Obesity?” USA Today: Are mosquitoes a cause of childhood obesity? Study: Child Outdoor Physical Activity is Reduced by Prevalence of the Asian Tiger Mosquito. Caloric Restriction Dietary Restriction Induced Longevity Is Mediated by Nuclear Receptor NHR-62 in Caenorhabditis elegans. Caloric Restriction-Mediated Induction of Lipid Metabolism Gene Expression in Liver is Enhanced by Keap1-Knockdown. RCT: A study of caloric restriction versus standard diet in overweight men with newly diagnosed prostate cancer. Clinical The impact of pharyngeal fat tissue on the pathogenesis of obstructive sleep apnea. RCT: Evaluation of a… Read More »