Key result
Successful weight loss maintenance preserved reductions in whole-body norepinephrine spillover rate, whereas muscle sympathetic nerve activity rebounded by 20 ± 5 bursts/100 heartbeats (P=0.0003).
Why the study?
Does active weight loss versus weight loss maintenance alter sympathetic nervous system activity in untreated subjects with metabolic syndrome?
RCT (n=18)
randomized
Does active weight loss versus weight loss maintenance alter sympathetic nervous system activity in untreated subjects with metabolic syndrome?
p-value: p=0.0003
While active weight loss reduces sympathetic nervous system overactivity in metabolic syndrome, weight maintenance leads to a rebound in muscle sympathetic nerve activity despite sustained weight loss.
Weight loss may reduce SNS overactivity in MetS; leaves open durability of benefits during maintenance and impact on outcomes.
CONTEXT: Sympathetic nervous system (SNS) overactivity participates in both the pathogenesis and adverse clinical complications of metabolic syndrome (MetS) obesity. OBJECTIVE: We conducted a prospective lifestyle intervention trial to compare the effects of active weight loss and extended weight loss maintenance on SNS function and MetS components. METHODS: Untreated subjects (14 males, four females; mean age, 53 ± 1 yr; body mass index, 30.9 ± 0.9 kg/m(2)) who fulfilled Adult Treatment Panel III criteria were randomized to 12-wk hypocaloric diet alone (n = 8) or together with aerobic exercise training (n = 10). This was followed by a 4-month weight maintenance period. Measurements of muscle sympathetic nerve activity (MSNA) by microneurography, whole-body norepinephrine kinetics, substrate oxidation by indirect calorimetry, baroreflex sensitivity, plasma renin activity (PRA), and MetS components were performed. RESULTS: Body weight decreased by 9.3 ± 0.8% at wk 12 (P < 0.001), and this was maintained. During active weight loss, norepinephrine spillover rate decreased by 23 ± 16% (P = 0.004), MSNA by 25 ± 3 bursts per 100 heartbeats (P < 0.001), and PRA by 0.25 ± 0.09 ng/ml · h (P = 0.007), whereas baroreflex sensitivity increased by 5.2 ± 2.2 msec/mm Hg (P = 0.005). After weight maintenance, beneficial effects of weight loss on norepinephrine spillover rate were preserved, whereas PRA and MSNA rebounded (by 0.24 ± 0.11 ng/ml · h, P = 0.02; and 20 ± 5 bursts/100 heartbeats, P = 0.0003), and baroreflex sensitivity was attenuated. CONCLUSIONS: Divergent effects of successful weight loss maintenance on whole-body norepinephrine spillover rate and MSNA suggest organ-specific differentiation in SNS adaptation to weight loss under conditions of negative vs. stable energy balance.
No takes yet. Share an insight, caveat, or question.
Straznicky et al. (2010) conducted an RCT in Metabolic syndrome obesity (n=18). Weight loss maintenance vs. Active weight loss phase was evaluated on Muscle sympathetic nerve activity (MSNA) and whole-body norepinephrine kinetics (p=0.0003). Successful weight loss maintenance preserved reductions in whole-body norepinephrine spillover rate, whereas muscle sympathetic nerve activity rebounded by 20 ± 5 bursts/100 heartbeats (P=0.0003).
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: