Associations of surgical and nonsurgical weight loss with knee musculature: a cohort study of obese adults

BACKGROUND

Marked weight loss reduces lean body mass and quadriceps thickness. It is unclear whether muscle loss varies according to the method of weight loss.

OBJECTIVE

This study compared the association of surgical versus nonsurgical weight loss with change in vastus medialis (VM) properties in obese adults.

METHODS

Twenty obese patients (body mass index ≥ 30 kg/m(2)) who lost weight via laparoscopic gastric banding were matched for weight loss with obese patients who lost weight nonsurgically. The thickness and fat infiltration of VM were assessed at baseline and a mean of 2.4 years later.

RESULTS

After adjusting for confounders, the annual change in VM thickness was -2.9% in the surgical group and -.5% for the nonsurgical group (P = .02). There was also a tendency toward an increased risk for VM fat infiltration to be reduced when weight loss occurred nonsurgically (OR 5.1, 95% CI .8-32.8; P = .09).

CONCLUSIONS

Compared with nonsurgical weight loss, laparoscopic gastric banding was associated with greater VM muscle thickness loss. Relative to laparoscopic gastric banding, there was also a tendency toward an increased risk for VM fat infiltration to be reduced with nonsurgical weight loss. Close attention to preserving muscle properties at the knee when significant amounts of weight loss have occurred is required. Physical therapy may be important in the management of patients after laparoscopic gastric banding in an attempt to preserve skeletal muscle mass.

Should the sympathetic nervous system be a target to improve cardiometabolic risk in obesity?

The sympathetic nervous system (SNS) plays a key role in both cardiovascular and metabolic regulation; hence, disturbances in SNS regulation are likely to impact on both cardiovascular and metabolic health. With excess adiposity, in particular when visceral fat accumulation is present, sympathetic activation commonly occurs. Experimental investigations have shown that adipose tissue releases a large number of adipokines, cytokines, and bioactive mediators capable of stimulating the SNS. Activation of the SNS and its interaction with adipose tissue may lead to the development of hypertension and end-organ damage including vascular, cardiac, and renal impairment and in addition lead to metabolic abnormalities, especially insulin resistance. Lifestyle changes such as weight loss and exercise programs considerably improve the cardiovascular and metabolic profile of subjects with obesity and decrease their cardiovascular risk, but unfortunately weight loss is often difficult to achieve and sustain. Pharmacological and device-based approaches to directly or indirectly target the activation of the SNS may offer some benefit in reducing the cardiometabolic consequences of obesity. Preliminary evidence is encouraging, but more trials are needed to investigate whether sympathetic inhibition could be used in obesity to reverse or prevent cardiometabolic disease development. The purpose of this review article is to highlight the current knowledge of the role that SNS plays in obesity and its associated metabolic disorders and to review the potential benefits of sympathoinhibition on metabolic and cardiovascular functions.

Pioglitazone treatment enhances the sympathetic nervous system response to oral carbohydrate load in obese individuals with metabolic syndrome

CONTEXT

Insulin resistance is associated with blunted sympathetic nervous system (SNS) response to carbohydrate ingestion which may contribute to postprandial hypotension and impaired body weight homeostasis.

OBJECTIVE

This study was conducted to examine the effects of pharmacological insulin sensitization on whole-body norepinephrine kinetics during a standard 75-g oral glucose tolerance test (OGTT) in obese, insulin resistant subjects with metabolic syndrome.

METHODS

Un-medicated individuals (n=42, mean age 56±0.8 yrs, body mass index 34±0.6 kg/m(2)) were randomised to 12-weeks pioglitazone (PIO, 15 mg for 6 weeks, then 30 mg daily) or placebo using a double-blind, parallel group design. Whole-body norepinephrine kinetics (arterial norepinephrine concentration, calculated spillover and clearance rates), spontaneous cardiac baroreflex sensitivity, heart rate and blood pressure were measured at times 0, 30, 60, 90 and 120 minutes during OGTT. Insulin sensitivity was assessed by euglycemic hyperinsulinemic clamp (M) and Matsuda index.

RESULTS

PIO increased clamp derived glucose utilisation by 35% (P<0.001) and there were concurrent reductions in inflammatory status and plasma triglycerides (P<0.05). Fasting norepinephrine kinetic parameters were unaltered. PIO treatment was associated with lower plasma insulin incursions, greater reduction in diastolic blood pressure and enhanced baroreflex sensitivity during OGTT (P all <0.05). The overall norepinephrine spillover response (AUC(0-120)) increased significantly in the PIO group (group × time interaction, P=0.04), with greatest increment at 30 minutes post-glucose (101±38 ng/min at baseline versus 241±48 ng/min post treatment, P=0.04) and correlated with percent improvement in M.

CONCLUSIONS

PIO enhances the early postprandial SNS response to carbohydrate ingestion.

Shorter Mandibular Length is Associated with a Greater Fall in AHI with Weight Loss

RATIONALE

Obesity is a major risk factor towards the development of obstructive sleep apnea, while significant weight loss (both conservatively managed and surgically assisted) has a variable effect upon its severity. Differences in the effect of weight loss on obstructive sleep apnea may be due to underlying craniofacial characteristics.

OBJECTIVES

To determine whether craniofacial characteristics can predict OSA treatment response to significant weight loss.

METHODS

We analyzed craniofacial measurements from lateral cephalograms performed at baseline on 57 patients enrolled in a previously reported 2-year randomized clinical weight loss trial (laparoscopic adjustable gastric band surgery versus conservatively [dietician and very low calorie diet] treated). Group mean weight loss was ∼ 13% (mean weight loss 131 to 114 kg), with corresponding reduction in mean apnea-hypopnea index (AHI) from 61 to 41 events/h. Computer assisted lateral cephalogram analysis was undertaken by three trained staff blinded to treatment. We analyzed lateral cephalogram and demographic data at baseline (cross-sectional) and change over two years (interventional) in 54 patients.

MEASUREMENTS AND MAIN RESULTS

Baseline cross-sectional analysis indicated no cephalometric measurement correlated significantly with baseline AHI when corrected for neck circumference. The percentage change in AHI over 2 years correlated with a shorter menton-gonion distance (i.e., mandibular body length). The % change in AHI correlated with the % weight change (R(2) = 0.25, p < 0.001) and mandibular body length (R(2) = 0.19, p = 0.002). The % change in AHI correlated with combined weight change and mandibular body length (combined R(2) = 0.31, p < 0.001).

CONCLUSIONS

Weight loss as a therapeutic option for severe OSA with severe obesity may be predicted by shorter mandibular body length as measured by lateral cephalometry.

Arterial norepinephrine concentration is inversely and independently associated with insulin clearance in obese individuals with metabolic syndrome

CONTEXT

Impaired insulin clearance contributes to the hyperinsulinemia of obesity, yet relatively little is known concerning the pathophysiological determinants of insulin clearance in obese populations.

OBJECTIVE

To examine the cross-sectional relationship between insulin clearance and resting sympathetic nervous system activity in a cohort of obese subjects with metabolic syndrome.

PARTICIPANTS AND METHODS

Unmedicated, nonsmoking subjects (31 male, 27 female; aged 56 ± 1 year; body mass index 33.7 ± 0.6 kg/m(2)) underwent euglycemic hyperinsulinemic clamp to determine insulin sensitivity (M) and insulin clearance, assessment of norepinephrine kinetics, peripheral arterial tonometry, Doppler echocardiography, and oral glucose tolerance test.

RESULTS

Univariate correlation analyses showed inverse associations between insulin clearance and arterial norepinephrine concentration (r = -0.44, P = .0006), calculated norepinephrine spillover rate (r = -0.33, P = .01), augmentation index (AI, r = -0.37, P = .005), and positive associations with M (r = 0.30, P = .02), Matsuda insulin sensitivity index (r = 0.27, P = .04), and cardiac output (r = 0.27, P = .04). Insulin clearance and sensitivity did not differ between genders, however females had higher AI compared to males (35 ± 3% versus 14 ± 2%, P < .001). In age and gender adjusted stepwise regression analyses, arterial norepinephrine concentration alone explained 19% of the variance in insulin clearance. When all significant variables were entered into the regression model, arterial norepinephrine, AI, gender, and M were independent predictors of insulin clearance, together explaining 41% of the variance.

CONCLUSIONS

Arterial norepinephrine concentration is inversely and independently associated with whole-body insulin clearance rate in obese individuals with metabolic syndrome. Prospective studies are needed to determine the direction of causality and the chronology of interactions between insulin clearance and sympathetic neural activity.

Fat-free mass loss generated with weight loss in overweight and obese adults: What may we expect?

There is concern that intentional weight loss may generate excessive loss of fat-free mass (FFM). Idealists target minimal loss of FFM, while others consider that FFM loss of up to 25% of weight loss is acceptable. In a cross-sectional study of 275 weight-stable, overweight or obese adults, we used whole-body dual-energy X-ray absorptiometry to measure FFM. A range of models was used to estimate the expected ΔFFM/Δweight ratio required to attain the body composition of a weight-stable individual at a lower body mass index (BMI). Higher BMI was associated linearly with higher FFM in men and women. Proportional ΔFFM/Δweight was influenced by sex, BMI and age. Direct scatter plot analysis, quadratic curve fit modelling and linear FFM-BMI modelling provided similar estimates for each model of ΔFFM/Δweight ratio, with 40% for men and 33% for women. These results show that the 25% rule is inappropriate and our estimates are higher than those generally reported after intentional weight loss indicating favourable preservation of FFM.

Sympathetic activity and markers of cardiovascular risk in nondiabetic severely obese patients: the effect of the initial 10% weight loss

BACKGROUND

Obesity is associated with elevated cardiovascular mortality, which may be attributed, in part, to sympathetic nervous system (SNS) activation and an associated poor metabolic profile. We examined the effects of laparoscopic adjustable gastric band (LAGB) on SNS activity and cardiovascular profile when the initial weight loss of 10%, corresponding to the recommendation of clinical guidelines, was reached.

METHODS

Direct muscle sympathetic nerve activity (MSNA, microneurography), baroreflex function, and cardiovascular profile were examined before and after a predetermined weight loss of 10% in 23 severely obese nondiabetic individuals.

RESULTS

The 10% weight loss was achieved at an average of 7.3 ± 1.4 months (range = 1.3-23.3 months). This was associated with significant improvement in office systolic and diastolic blood pressure (BP) (-12 mm Hg and -5 mm Hg, respectively), a decrease in MSNA (33 ± 3 to 22 ± 3 bursts per minute), improvement in cardiac (16 ± 3 to 31 ± 4 ms/mm Hg) and sympathetic (-2.23 ± 0.39 to -4.30 ± 0.96 bursts/100 heartbeats/mm Hg) baroreflex function, total cholesterol (5.33 ± 0.13 to 4.97 ± 0.16 mmol/L), fasting insulin (29.3 ± 2.4 to 19.6 ± 1.1 mmol/L), and creatinine clearance (172 ± 11 to 142 ± 8 ml/min). None of the cardiovascular risk improvement related to the rate of weight loss. The change in systolic and diastolic BP correlated with change in waist circumference (r = 0.46, P = 0.04; r = 0.50, P = 0.02, respectively).

CONCLUSIONS

The initial 10% weight loss induced by LAGB was associated with substantial hemodynamic, metabolic, SNS, and renal function improvements. Changes in waist circumference appear to be an important factor contributing to BP adaptation after LAGB surgery.

Control of type 2 diabetes after 1 year of laparoscopic adjustable gastric banding in the helping evaluate reduction in obesity (HERO) study

AIMS

The 5-year, open-label, prospective, observational helping evaluate reduction in obesity (HERO) study (N = 1106) examines efficacy and safety of the LAP-BAND AP(®) laparoscopic adjustable gastric band (LAGB) in obese patients. This interim analysis assessed the control of type 2 diabetes (T2D), 1 year after the implantation of the LAGB.

METHODS

Baseline T2D was defined by chart review or use of antidiabetic medications or haemoglobin A1c (HbA1c) ≥ 7.0%. Control of T2D at 1 year was defined as A1c <7.0% (with or without antidiabetic medications).

RESULTS

After 1 year, 187 of 273 patients with T2D at baseline had adequate data available to assess T2D status, of which 135 patients (72.2%) achieved target control of T2D compared with 42.8% control rate at baseline. Independent predictors of achieving target control at 1 year included the following: (i) shorter diabetes duration odds ratio (OR) 0.914 [95% confidence interval (CI), 0.839, 0.995, p = 0.038], (ii) not using insulin therapy OR 0.16 (95% CI, 0.06, 0.47, p < 0.001) and (iii) greater mean % weight loss OR 1.176 (95% CI, 1.093, 1.266, p < 0.001). Patients using insulin at baseline were 84% less likely to achieve control of T2D after 1 year; each additional year of diabetes at baseline reduced the likelihood of good control by 9%; and each 1% of weight loss increases the likelihood of good control by 18%. Rates of device-related adverse events and reoperations were low and were not significantly different between patients with and without baseline T2D at 1 year.

CONCLUSIONS

Greater % weight loss, not using insulin therapy, and shorter disease duration predicted increased likelihood of target control of T2D, 1 year after implantation of the LAGB.

Relationship between mental health and foot pain

OBJECTIVE

Although mental health is related to the persistence of musculoskeletal pain, our understanding of the relationship between mental health and foot pain is limited. Subsequently, we conducted a 3-year longitudinal study to examine the relationship between mental health and foot pain in a community-based population.

METHODS

Eighty-three community-dwelling participants (mean ± SD body mass index [BMI] 35.3 ± 9.0 kg/m2) who had foot pain at study inception in 2008 and for whom measures of mental health (Short Form 36 [SF-36] health survey mental component summary [MCS]) were available, were invited to take part in this followup study in 2011. Change in foot pain was determined by the difference between the Manchester Foot Pain and Disability Index score at baseline and followup; therefore, a decrease in the score indicated improved foot pain and an increase indicated deterioration in foot pain. Linear regression was used to determine the factors affecting change in foot pain.

RESULTS

Of the 62 respondents (75% response rate, 49 women and 13 men), there were 27 (44%) whose foot pain deteriorated. A higher MCS score of the SF-36 health survey at baseline was associated with a slower progression of foot pain (β coefficient −0.29, 95% confidence interval −0.42, −0.01), adjusted for age, sex, BMI, and physical health.

CONCLUSION

Mental health is associated with changes in foot pain. Clinicians dealing with this population should consider the contribution of mental health in their management and treatment of foot pain.

A randomized controlled trial of the effects of pioglitazone treatment on sympathetic nervous system activity and cardiovascular function in obese subjects with metabolic syndrome

CONTEXT

Insulin resistance and sympathetic nervous system overactivity are closely associated and contribute to cardiovascular risk.

OBJECTIVE

The objective of the study was to test the hypotheses that pharmacological improvement in insulin sensitivity would (1) attenuate sympathetic neural drive and (2) enhance neuronal norepinephrine uptake.

PARTICIPANTS AND METHODS

A randomized, double-blind trial was conducted in 42 obese, unmedicated individuals with metabolic syndrome (mean age 56 ± 1 y, body mass index 34 ± 0.6 kg/m(2)) who received 12 weeks of pioglitazone (PIO; 15 mg for 6 wk, then 30 mg daily) or matched placebo. Clinical measurements included whole-body norepinephrine kinetics [spillover rate, plasma clearance, and the steady state ratio of tritiated 3,4-dihydroxyphenylglycol to tritiated norepinephrine ([(3)H]-DHPG to [(3)H]-NE) as an index of neuronal uptake-1], muscle sympathetic nerve activity, spontaneous baroreflex sensitivity, euglycemic hyperinsulinemic clamp, oral glucose tolerance test, ambulatory blood pressure, and Doppler echocardiography.

RESULTS

PIO treatment increased glucose uptake by 35% and was accompanied by significant reductions in diastolic blood pressure and improved left ventricular diastolic and endothelial function. Resting muscle sympathetic nerve activity burst frequency decreased by -6 ± 3 burst/min compared with baseline (P = .03), but the magnitude of change was not different from placebo (P = .89). Norepinephrine spillover and clearance rates and baroreflex sensitivity were unchanged. Post hoc subgroup analyses revealed an 83% increase in [(3)H]-DHPG to [(3)H]-NE ratio in hyperinsulinemic (P = .04) but not normoinsulinemic subjects (time × group interaction, P = .045). Change in [(3)H]-DHPG to [(3)H]-NE ratio correlated with improvements in diastolic blood pressure (r = -0.67, P = .002), the ratio of early (E) to late (A) peak transmitral diastolic inflow velocity (r = 0.62, P = .008), E wave deceleration time (r = -0.48, P = .05), and Δinsulin area under the curve0-120 during the oral glucose tolerance test (r = -0.42, P = .08).

CONCLUSIONS

Compared with placebo, PIO does not affect resting sympathetic drive or norepinephrine disposition in obese subjects with metabolic syndrome. Treatment induced changes in the [(3)H]-DHPG to [(3)H]-NE ratio related to reduction in hyperinsulinemia and improvements in diastolic function.

Self-reported access to and quality of healthcare for diabetes: do the severely obese experience equal access?

BACKGROUND

Given reported pejorative views that health professionals have about patients who are severely obese, we examined the self-reported views of the quality and availability of diabetes care from the perspective of adults with type 2 diabetes (T2DM), stratified by body mass index (BMI).

METHODS

1795 respondents to the Diabetes MILES - Australia national survey had T2DM. Of these, 530 (30%) were severely obese (BMI ≥35 kg/m²) and these participants were matched with 530 controls (BMI <35 kg/m²). Data regarding participants' self-reported interactions with health practitioners and services were compared.

RESULTS

Over 70% of participants reported that their general practitioner was the professional they relied on most for diabetes care. There were no between-group differences in patient-reported availability of health services, quality of interaction with health practitioners, resources and support for self-management, or access to almost all diabetes services.

DISCUSSION

Participants who were severely obese did not generally report greater difficulty in accessing diabetes care.

Sentinel lymph node biopsy now has a limited role in melanoma management

SLNB is confirmed as a prognostic test but does not influence melanoma-specific survival at 10 years. SLNB-negative patients still need regular review and can still die from their melanoma. SLNB-positive patients should be carefully counselled regarding the risks and very limited benefit (if any) of proceeding to CL. SLNB should not be regarded as essential or standard of care for patients with melanomas. SLNB should be discussed with patients with intermediate-thickness melanoma. Note that ‘discuss’ is not the same as ‘offer’ or ‘recommend’. The discussion should include: • SLNB does not alter survival prospects • SLNB provides added accuracy to survival prognostic figures−−70% vs. 90% for melanoma Breslow thickness of 1.2–3.5 mm • SLNB has a 10% complication rate • If positive, no added treatment can be offered that has demonstrated survival benefits−− this includes no apparent survival benefit in proceeding to CL−− SLNB-positive patients can be offered enrolment into further melanoma studies.

The effects of dietary weight loss on indices of norepinephrine turnover: modulatory influence of hyperinsulinemia

OBJECTIVES

This study was conducted to examine (1) the effects of dietary weight loss on indices of norepinephrine (NE) turnover and (2) whether baseline hyperinsulinemia modulates sympathetic neural adaptations.

METHODS

Obese individuals aged 56 ± 1 year, BMI 32.5 ± 0.4 kg/m(2) , with metabolic syndrome, underwent a 12-week hypocaloric diet (HCD, n = 39) or no treatment (n = 26). Neurochemical measurements comprised arterial dihydroxyphenylalanine (DOPA), 3,4-dihydroxyphenylglycol (DHPG), and NE concentrations, the steady-state ratio of [3H]-DHPG to [3H]-NE, as an index of neuronal uptake, and calculated whole-body plasma NE clearance and spillover rates.

RESULTS

Body weight decreased by -7.4 ± 0.5% in HCD group (P < 0.001) and was accompanied by reductions in DOPA, NE, and DHPG averaging -14 ± 5% (P = 0.001), -23 ± 4% (P <0.001), and -5 ± 4% (P = 0.03), respectively. NE spillover rate decreased by -88 ± 39 ng/min (P = 0.01), whereas neuronal uptake and NE plasma clearance were unchanged. Despite similar weight loss, hyperinsulinemic subjects exhibited greater reductions in NE and NE spillover rate, compared to normoinsulinemic subjects (group by time interaction P < 0.05).

CONCLUSIONS

Weight loss is associated with down-regulation of sympathetic nervous activity but no overall alteration in disposition indices. Hyperinsulinemic subjects derive a greater sympathoinhibitory benefit during weight loss.

Weight change and change in tibial cartilage volume and symptoms in obese adults

INTRODUCTION

There is a paucity of data examining the effects of weight change on knee joint structures and symptoms. This study examined the effect of weight change on change in knee cartilage volume and symptoms in an obese cohort.

METHODS

112 obese subjects (Body Mass Index ≥30 kg/m(2)) were recruited from various community sources to examine the effect of obesity on musculoskeletal health. Tibial cartilage volume, determined by MRI, and knee symptoms, determined by the Western Ontario and McMaster Osteoarthritis Index (WOMAC) were collected at baseline and an average of 2.3 years later.

RESULTS

Percentage weight change was associated with change in medial tibial cartilage volume (β -1.2 mm(3), 95% CI -2.3 to -0.1 mm(3), p=0.03) that was consistent throughout the spectrum of weight loss through to mild weight gain. Percentage weight change was not associated with change in the lateral tibial (p=0.93) or patella (p=0.32) cartilage volumes. Percentage weight change was associated with change in all WOMAC subscales (all p≤0.01): pain (β -1.8 mm, 95% CI -3.2 to -0.4 mm), stiffness (β -1.6 mm, 95% CI -2.5 to -0.7 mm) and function (β -6.9 mm, 95% CI -11.6 to -2.1 mm).

CONCLUSIONS

The linearity of effect implies that weight loss is associated with reduced medial cartilage volume loss and improved knee symptoms, while weight gain is associated with increased medial cartilage volume loss and worse knee symptoms. These results suggest that in obese people, small amounts of weight change may have the potential for a disease modifying effect on both knee joint structure and symptoms. While weight loss is an important primary management strategy in obese individuals, avoidance of further weight gain should also be a clinical goal.

Severe obesity and diabetes self-care attitudes, behaviours and burden: implications for weight management from a matched case-controlled study. Results from Diabetes MILES--Australia

AIMS

To investigate whether diabetes self-care attitudes, behaviours and perceived burden, particularly related to weight management, diet and physical activity, differ between adults with Type 2 diabetes who are severely obese and matched non-severely obese control subjects.

METHODS

The 1795 respondents to the Diabetes MILES--Australia national survey had Type 2 diabetes and reported height and weight data, enabling BMI calculation: 530 (30%) were severely obese (BMI ≥ 35 kg/m(2); median BMI = 41.6 kg/m(2)) and these were matched with 530 control subjects (BMI < 35 kg/m(2); median BMI = 28.2 kg/m(2)). Diabetes self-care behaviours, attitudes and burden were measured with the Diabetes Self-Care Inventory-Revised. Within-group and between-group trends were examined.

RESULTS

The group with BMI ≥ 35 kg/m(2) was less likely to achieve healthy diet and exercise targets, placed less importance on diet and exercise recommendations, and found the burden of diet and exercise recommendations to be greater than the group with BMI < 35 kg/m(2). The group with BMI ≥ 35 kg/m(2) was more likely to be actively trying to lose weight, but found weight control a greater burden. These issues accentuated with increasing obesity and were greatest in those with BMI > 45 kg/m(2). There were no between-group differences in other aspects of diabetes self-care: self-monitoring of blood glucose, use of medications and smoking. Moderate-to-severe symptoms of depression were independently associated with reduced likelihood of healthy diet and physical activity, and with greater burden associated with diet, physical activity and weight management.

CONCLUSIONS

Severely obese people with diabetes demonstrated self-care attitudes, behaviours and burdens that infer barriers to weight loss. However, other important diabetes self-care behaviours are supported equally by severely obese and non-severely obese individuals.