Relationship between sleep apnea, fat distribution, and insulin resistance in obese children.

BACKGROUND: Obstructive sleep apnea (OSA) is associated with obesity, inflammation, and insulin resistance. The role of fat distribution in OSA pathogenesis has not been established in children. The objective of the study is to examine the relationship between fat distribution, OSA, and insulin resistance in an unselected population of obese children. METHODS: All obese (BMI > 95th percentile) children (ages 5-18 y) seen at a pediatric obesity clinic were invited to participate. Subjects underwent polysomnography, and were tested for dyslipidemia, inflammation, and insulin resistance measured by the homeostasis model assessment (HOMA). In a subset of subjects, magnetic resonance (MRI) imaging was used to determine the abdominal visceral and subcutaneous adipose tissue areas and magnetic resonance spectroscopy (MRS) spectroscopy was used to intramyocellular lipids in leg muscles. MEASUREMENTS AND MAIN RESULTS: 31 obese subjects enrolled and completed polysomnography and serum testing, and 19 subjects underwent MRI/MRS. The mean age was 12.6 ± 3.0 y and the mean body mass index (BMI) was 39.5 ± 11.2 kg/m(2). Forty-eight percent had OSA (mean apnea hypopnea index [AHI] 6.26 ± 6.77 events/h) Subjects with OSA had significantly increased BMI, log HOMA, triglycerides, and leptin compared to those without OSA. In regression analysis, only BMI z-score was associated with log HOMA. In the subset of patients with imaging data, visceral fat area was strongly predictive of AHI (p = 0.003, r(2) = 0.556). BMI z-score, gender, and age were not predictive. CONCLUSIONS: Visceral fat distribution is independently predictive of OSA severity in obese children.

Roux-en-Y gastric bypass enhances energy expenditure and extends lifespan in diet-induced obese rats.

Gastrointestinal weight-loss surgery (GIWLS) is currently the most effective treatment for severe obesity, with Roux en-Y gastric bypass (RYGB) among the best of the available surgical options. Despite its widespread clinical use, the mechanisms by which RYGB induces its profound weight loss remain largely unknown. This procedure effects weight loss by altering the physiology of weight regulation and eating behavior rather than by simple mechanical restriction and/or malabsorption as previously thought. To study how RYGB affects the physiology of energy balance, we developed a rat model of this procedure. In this report, we demonstrate that RYGB in diet-induced obese (DIO) rats induces a 25% weight loss, prolongs mean survival by 45%, and normalizes glucose homeostasis and lipid metabolism. RYGB induced a 19% increase in total and a 31% increase in resting energy expenditure (REE). These effects, along with a 17% decrease in food intake and a 4% decrease in nutrient absorption account for the normalization of body weight after this procedure. These effects indicate that surgery acts by altering the physiology of weight regulation and help to explain the effectiveness of RYGB in comparison to restrictive dieting and other forms of dietary and pharmacological therapies for obesity. The clinical effectiveness of RYGB and its physiological effects on body weight regulation and energy expenditure (EE) suggest that this operation provides a unique opportunity to explore the mechanisms of energy homeostasis and to identify novel therapies for obesity and related metabolic diseases.

Best practice updates for pediatric/adolescent weight loss surgery.

The objective of this study is to update evidence-based best practice guidelines for pediatric/adolescent weight loss surgery (WLS). We performed a systematic search of English-language literature on WLS and pediatric, adolescent, gastric bypass, laparoscopic gastric banding, and extreme obesity published between April 2004 and May 2007 in PubMed, MEDLINE, and the Cochrane Library. Keywords were used to narrow the search for a selective review of abstracts, retrieval of full articles, and grading of evidence according to systems used in established evidence-based models. In light of evidence on the natural history of obesity and on outcomes of WLS in adolescents, guidelines for surgical treatment of obesity in this age group need to be updated. We recommend modification of selection criteria to include adolescents with BMI >or= 35 and specific obesity-related comorbidities for which there is clear evidence of important short-term morbidity (i.e., type 2 diabetes, severe steatohepatitis, pseudotumor cerebri, and moderate-to-severe obstructive sleep apnea). In addition, WLS should be considered for adolescents with extreme obesity (BMI >or= 40) and other comorbidities associated with long-term risks. We identified >1,085 papers; 186 of the most relevant were reviewed in detail. Regular updates of evidence-based recommendations for best practices in pediatric/adolescent WLS are required to address advances in technology and the growing evidence base in pediatric WLS. Key considerations in patient safety include carefully designed criteria for patient selection, multidisciplinary evaluation, choice of appropriate procedure, thorough screening and management of comorbidities, optimization of long-term compliance, and age-appropriate fully informed consent.

Adolescent obesity and bariatric surgery.

PURPOSE OF REVIEW: Examines the effects of bariatric surgery on adolescent obesity. RECENT FINDINGS: The risks and outcomes of bariatric surgery in adolescence are presently being defined and may be somewhat different from those in adults. Adolescents may have a greater risk of weight regain, and greater risk of noncompliance to treatment after surgery. However, long-term outcomes are not yet available, and the underlying metabolic benefits appear to be substantial and similar to those of adults. SUMMARY: Morbid obesity in adolescents has severe acute and chronic complications. Bariatric surgery in adolescents seems as well tolerated as in adults when performed in centers with appropriate experience and adequate surgical volume. The pathophysiologic implications of bariatric surgery are profound. A better understanding of the mechanisms leading to postsurgical improvement in insulin resistance and weight loss could lead to the development of other therapies to achieve the same effects with lesser morbidities.

Effects of sibutramine treatment in obese adolescents: a randomized trial.

BACKGROUND: Increased prevalence of adolescent obesity requires effective treatment options beyond behavior therapy. OBJECTIVE: To see whether sibutramine reduced weight more than placebo in obese adolescents who were receiving a behavior therapy program. DESIGN: 12-month, 3:1 randomized, double-blind trial conducted from July 2000 to February 2002. SETTING: 33 U.S. outpatient clinics. PARTICIPANTS: 498 participants 12 to 16 years of age with a body mass index (BMI) that was at least 2 units more than the U.S. weighted mean of the 95th percentile based on age and sex, to the upper limit of 44 kg/m2. INTERVENTIONS: Site-specific behavior therapy plus 10 mg of sibutramine or placebo. Blinded study medication dose was uptitrated to 15 mg or placebo at month 6 if initial BMI was not reduced by 10%. MEASUREMENTS: Body mass index, waist circumference, body weight, fasting lipid and glycemic variables, safety, and tolerability. RESULTS: Seventy-six percent of patients in the sibutramine group and 62% of patients in the placebo group completed the study. The estimated mean treatment group difference at month 12 (linear mixed-effects model) favored sibutramine for change from baseline in BMI (-2.9 kg/m2 [95% CI, -3.5 to -2.2 kg/m2]) and body weight (-8.4 kg [CI, -9.7 to -7.2 kg]) (P < 0.001 for both). The sibutramine group had greater improvements in triglyceride levels, high-density lipoprotein cholesterol levels, insulin levels, and insulin sensitivity (P < or = 0.001 for all). The rate of tachycardia was greater with sibutramine vs. placebo (12.5% vs. 6.2%; difference, 6.3 percentage points [CI, 1.0 to 11.7 percentage points]) but did not lead to increased withdrawal (2.4% vs. 1.5%; difference, 0.9 percentage point [CI, -1.7 to 3.5 percentage points]). LIMITATIONS: The 1-year study duration precluded assessment of long-term weight maintenance and putative health benefits and harms, and 24% and 38% of the sibutramine and placebo groups, respectively, did not complete follow-up. CONCLUSIONS: Sibutramine added to a behavior therapy program reduced BMI and body weight more than placebo and improved the profile of several metabolic risk factors in obese adolescents.

Best practice guidelines in pediatric/adolescent weight loss surgery.

OBJECTIVE: To establish evidence-based guidelines for best practices in pediatric/adolescent weight loss surgery (WLS). RESEARCH METHODS AND PROCEDURES: We carried out a systematic search of English-language literature in MEDLINE on WLS performed on children and adolescents. Key words were used to narrow the field for a selective review of abstracts. Data were extracted, and evidence categories were assigned according to a grading system based on established evidence-based models. Eight pertinent case series, published between 1980 and 2004, were identified and reviewed. These data were supplemented with expert opinions and literature on WLS in adults. RESULTS: Recommendations focused on patient safety, reduction of medical errors, systems improvements, credentialing, and future research. We developed evidence-based criteria for eligibility, assessment, treatment, and follow-up; recommended surgical procedures based on the best available evidence; and established minimum guideline requirements for data collection. DISCUSSION: Lack of adequate data and gaps in knowledge were cited as important reasons for caution. Physiological status, comprehensive screening of patients and their families, and required education and counseling were identified as key factors in assessing eligibility for surgery. Data collection and peer review were also identified as important issues in the delivery of best practice care.

Obesity and the liver: developmental perspectives.

Obesity now affects 15% of children and adolescents in the United States. Many of the complications of obesity are seen in children, including fatty liver disease, gallstones, hyperlipidemia, insulin resistance, and type 2 diabetes. Infants and children also have unique susceptibilities to and manifestations of liver disease caused by total parenteral nutrition. In addition to genetic and environmental influences on obesity, there is increasing evidence supporting the idea of "metabolic programming," in which environmental influences at critical periods during development have permanent effects on an individual's predisposition to obesity and metabolic disease. Understanding the role the liver plays in the development and expression of the metabolic program will provide important insight into the pathogenesis and treatment of fatty liver disease, and of obesity itself.