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Metabolic and endocrine benefits

Post-op teens maintain metabolic and endocrine gains

YGB-induced energetic adaptations were observed in TEE and its components after surgery, the majority of the adaptive thermogenesis occurred by 1.5 months after surgery

Extremely obese adolescents who underwent Roux-en-Y gastric bypass (RYGB) surgery had substantial health benefits, according to a paper Energetic adaptations persist after bariatric surgery in severely obese adolescents, published in the journal Obesity. The research demonstrated that surgery induced persistent energetic, metabolic and endocrine adaptation, as well as improving insulin sensitivity, decreasing heart rate and reducing inflammation.

Although it is known that bariatric surgery results in energetic changes that are favourable to weight loss, exactly how this process works and whether the process is as effective in extremely obese adolescents is yet to be determined.

Therefore, the paper’s authors decided to examine the “energetic, metabolic, and neuroendocrine responses to RYGB surgery in extremely obese adolescents” after surgery, and the report:

  • on the changes in weight and body composition using a multi-compartment model;
  • measure changes in neuroendocrine factors;
  • measure 24-h energy expenditure (EE) and substrate utilization using room respiration calorimetry; and
  • identify neuroendocrine factors associated with the changes in EE and substrate utilisation.

The 12-month prospective study recruited 11 extremely obese adolescents and compared the outcomes from surgery against a five control patients matched for initial weight, BMI and body composition.


The mean age at enrolment was 16.5 ± 0.8 years in the RYGB group and 14.8 ± 1.2 years in the control group (p=0.03), and at baseline there were no significant differences between the groups. In the RYGB group, mean total weight lost was 44±19kg (30%±11%) of initial body weight at 12 months. Body composition changed significantly in the RYGB group (p< 0.001), but not in the controls.

Total EE (TEE) and its components measured by 24-h calorimetry and adjusted for age and sex, showed significant group × time interactions (p= 0.001-0.01), but not in the control group. TEE and sleep EE declined by 24% and 24% at 1.5 months, and then remained at the suppressed level at 6 and 12 months after surgery.

Postsurgical TEE (kcal/day), BMR (kcal/min), and sleep EE (kcal/min) were still significantly lower than baseline (p=0.001).  In addition to changes in basal energy requirements, the energy expended in physical activity also declined.

In addition, the researchers note that RYGB-induced energetic adaptations were observed in TEE and its components after surgery, the majority of the adaptive thermogenesis occurred by 1.5 months after surgery.

“We demonstrate that energetic adaptations in response to RYGB surgery in severely obese adolescents 1) are not totally explained by weight, FFM, or FM loss, 2) are associated with changes in insulin, leptin, adiponectin, T3, gut hormones, and SNS activity, and 3) persist 12 months after surgery despite a diminishing rate of weight loss,” the researchers note. ““The elucidation of these adaptations induced by weight loss after RYGB surgery will be instrumental in guiding the clinical management of these patients to prevent recidivism and future research into alternate surgical and nonsurgical treatments for morbid obesity.”

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