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Changes in Basal Metabolic Rate following Gastric Bypass surgery

Published online by Cambridge University Press:  06 September 2018

F. Naseer
Affiliation:
Nutrition Innovation Centre for food and Health (NICHE), Ulster University, School of Biomedical Science, Coleraine BT52 1SA, UK
R.K. Price
Affiliation:
Nutrition Innovation Centre for food and Health (NICHE), Ulster University, School of Biomedical Science, Coleraine BT52 1SA, UK
A. Boyd
Affiliation:
Nutrition Innovation Centre for food and Health (NICHE), Ulster University, School of Biomedical Science, Coleraine BT52 1SA, UK
T. Redpath
Affiliation:
Nutrition Innovation Centre for food and Health (NICHE), Ulster University, School of Biomedical Science, Coleraine BT52 1SA, UK
D. Liddy
Affiliation:
Nutrition Innovation Centre for food and Health (NICHE), Ulster University, School of Biomedical Science, Coleraine BT52 1SA, UK
M.B.E. Livingstone
Affiliation:
Nutrition Innovation Centre for food and Health (NICHE), Ulster University, School of Biomedical Science, Coleraine BT52 1SA, UK
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Abstract

Type
Abstract
Copyright
Copyright © The Authors 2018 

Gastric Bypass (GB) surgery continues to be one of the few effective treatments for sustainable weight loss in obese individuals (Reference Colquitt, Pickett and Loveman1). Apart from the primary weight loss mechanisms of energy restriction and malabsorption, studies have postulated that GB is associated with an increased shift in energy expenditure (EE) that contributes to sustained weight loss in the longer-term (Reference Faria, Faria and Buffington2Reference Stylopoulos, Hoppin and Kaplan5). However this positive effect on EE in humans remain equivocal. The effect has mainly been observed in experimental animal studies which adjusted EE for changes in total body weight (TBW) and body composition (BC) observed postoperatively (Reference Hao, Mumphrey and Townsend3Reference Stylopoulos, Hoppin and Kaplan5).

The aim of this study was to assess the impact of GB on Basal Metabolic Rate (BMR) in 17 GB patients (5 males; BMI 45·8 ± 6·3 kg/m2; 47·2 ± 13 y) and 13 time-matched and weight-stable controls (5 males; BMI 25·8 ± 4·3 kg/m2; 39·4 ± 15·1 y) at baseline (one month pre-surgery) and at three months post-surgery. BMR was measured under standardised conditions using indirect calorimetry (ECAL, Metabolic Health Solutions). Lean body mass (LBM) and fat mass (FM) were measured using dual energy X-ray absorptiometry (DEXA, GE Healthcare). BMR values were expressed per kg of TBW, LBM and FM. A paired sample t-test was used to compare changes in BMR between baseline and 3 months post-surgery.

Mean absolute BMR (kJ/day), TBW (kg), BMI (kg/m2), LBM (kg) and FM (kg) significantly decreased by 16·1 ± 21%, 16·9 ± 4·3%, 16·7 ± 4·4%, 9·8 ± 4·7% and 24·7 ± 7·1% respectively in patients (P < 0·05) and by -0·5 ± 24·4% 1·1 ± 2·4%, 0·4 ± 2·8%, 0·3 ± 3·1% and 2·1 ± 8·1% respectively in controls (all non-significant). When expressed relative to TBW and LBM, GB attenuated the compensatory reductions in BMR while BMR expressed relative to FM increased three months post-surgery in patients.

Fig. 1. Changes in BMR expressed per kg of TBW, LBM, and FM at three months post-surgery in patients and controls. FM fat mass, LM lean body mass, TBW total body weight.

In conclusion, weight loss following GB is associated with a favourable increase in BMR when expressed relative to postoperative changes in TBW and BC. This may contribute to the successful weight loss outcomes observed postoperatively. Further research is warranted to elucidate the underlying mechanism for this apparent beneficial impact of GB on BMR.

References

1.Colquitt, J, Pickett, K, Loveman, E et al. (2014) Cochrane Database of Syst Rev 8(8).Google Scholar
2.Faria, S, Faria, O, Buffington, C et al. (2012) Obes Surg 22(9), 14501455.Google Scholar
3.Hao, Z, Mumphrey, M, Townsend, R et al. (2016) Obes Surg 26(9), 21732182.Google Scholar
4.Nestoridi, E, Kvas, S, Kucharczyk, J et al. (2012) Endocrinology 153(5), 2234–44.Google Scholar
5.Stylopoulos, N, Hoppin, AG & Kaplan, LM (2009) Obesity 17(10), 1893–47.Google Scholar
Figure 0

Fig. 1. Changes in BMR expressed per kg of TBW, LBM, and FM at three months post-surgery in patients and controls. FM fat mass, LM lean body mass, TBW total body weight.