Independent Evolution of Heart Autonomic Function and Insulin Sensitivity During Weight Loss

Abstract

In order to investigate the improvement of insulin resistance and cardiac autonomic function along massive weight loss, 12 obese women were evaluated before, and 3 and 12 months after Roux‐en‐Y gastric bypass. The 12‐month values were compared to those of BMI‐matched controls. Insulin sensitivity was assessed by euglycemic clamp and the cardiac autonomic function by the analysis of the Heart Rate Variability (HRV). After surgery, glucose uptake progressively increased from 4.3 ± 0.5 mg/kg lean body mass (LBM)/min preoperative (pre‐op) to 4.9 ± 0.5 and 7.0 ± 0.5, 3‐ and 12‐month postoperative (post‐op) (P = 0.04 and P = 0.006 vs. pre‐op), whereas the cardiac autonomic function showed a biphasic pattern. HRV values increased 3 months post‐op, and decreased at 12 months, thus indicating an early sympathetic withdrawal followed by a later reactivation (e.g., the standard deviation of the normal‐to‐normal intervals was 116 ± 7 ms in pre‐op, 161 ± 10 at 3 months, P = 0.008 vs. pre‐op, and 146 ± 15 at 12 months, P = 0.03 vs. pre‐op and P = 0.02 vs. 3 m). Insulin sensitivity was significantly related to body weight (P = 0.02), whereas the cardiac indexes were significantly linked to the profile of energy intake (e.g., HRV triangular index vs. energy intake P = 0.003). No significant relationship linked insulin sensitivity to the cardiac autonomic indexes. Insulin sensitivity and cardiac parameters of the 12‐month post‐op patients were similar to their matched controls. During massive weight loss, the cardiac autonomic deregulation and insulin resistance improved concomitantly but independently from each other. Our results suggest that the extent of the improvement is associated with the final body weight.

Effects of Physical Training on Cardiac Modulation in Normal Weight, Overweight, and Obese Individuals: A Comparative Study

“…In fact, all these results show that the causes of impairment in cardiac autonomic modulation are still unclear, thus requiring further investigation on the correlation between autonomic dysfunctions and possible metabolic disorders; however this supposition was not addressed in the present study [29][30]. On the other hand, our study has shown that physical training can attenuate the cardiac autonomic modulation impairment in both obese and overweight women.…”

Effect of Low-Energy Diets Differing in Fiber, Red Meat, and Coffee Intake on Cardiac Autonomic Function in Obese Individuals With Type 2 Diabetes

“…Weight loss induced by caloric restriction appears to exert favorable effects on ANS activity via enhancing vagal activity and/or reducing sympathetic modulation in overweight or obese otherwise healthy individuals (7)(8)(9)(10)(11)(12). However, the results across studies are inconsistent, and the mechanisms implicated in these effects are unclear.…”

“…In glucose-tolerant obese subjects, chronic hyperinsulinemia was associated with persistent baroreflex downregulation and episodic (postprandial) sympathetic dominance, and reversal of these changes by weight loss suggested a causal role for insulin (13). However, in normoglycemic obese women, weight loss after Roux-en-Y gastric bypass independently improved HRV and glucose uptake (10). Caloric restriction in overweight individuals over 6 months was accompanied by improved vagal activity and reduced sympathetic activity only when combined with exercise despite weight loss comparable to caloric restriction only (11).…”

Análisis de variabilidad del ritmo cardiaco y su relación con la sensibilidad insulínica en pacientes obesos y con sobrepeso

“…Por otra parte, la RI se define como una disminución a la respuesta fisiológica a la insulina por parte de los tejidos, particularmente a nivel del tejido muscular y adiposo 27 . Si se considera a la obesidad y el sobrepeso como la característica principal de la muestra del presente estudio, se presume que existe un estilo de vida poco saludable, caracterizado por el desbalance entre el gasto y el consumo calóri-co, constituyendo una serie de factores de riesgo para el desarrollo de anormalidades metabólicas, disautonomía y síndrome metabólico 7,28 . Sumado a esto, existen estudios epidemioló-gicos que han demostrado que la obesidad y RI, se asocian con un incremento de la FC de reposo debido a un estímulo adrenérgico 20 .…”