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. 2020 Aug;30(8):3119-3126.
doi: 10.1007/s11695-020-04654-6.

Rate and Determinants of Excessive Fat-Free Mass Loss After Bariatric Surgery

Malou A H Nuijten  1 , Valerie M Monpellier  2 , Thijs M H Eijsvogels  1 , Ignace M C Janssen  2 , Eric J Hazebroek  3 , Maria T E Hopman  4
Affiliations

Rate and Determinants of Excessive Fat-Free Mass Loss After Bariatric Surgery

Malou A H Nuijten et al. Obes Surg. 2020 Aug.

Abstract

Purpose: Fat-free mass (FFM) loss is a concerning aspect of bariatric surgery, but little is known about its time-course and factors related with excessive FFM loss. This study examined (i) the progress of FFM loss up to 3 years post-bariatric surgery and (ii) the prevalence and determinants of excessive FFM loss.

Materials and methods: A total of 3596 patients (20% males, 43.5 ± 11.1 years old, BMI = 44.2 ± 5.5 kg/m2) underwent sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) surgery. Bioelectrical impedance analysis was performed preoperatively and 3, 6, 9, 12, 18, 24 and 36 months post-surgery. Changes in body composition were assessed by mixed model analysis. Prevalence of excessive FFM loss (based on three different cutoff values: ≥ 25%, ≥ 30% and ≥ 35% FFM loss/weight loss (= %FFML/WL)) was estimated and its determinants were assessed by linear regression analysis.

Results: Highest rates of FFM loss were found at 3 and 6 months post-surgery, reflecting 57% and 73% of peak FFM loss, respectively. Prevalence of excessive FFM loss ranged from 14 to 46% at 36 months post-surgery, with an older age (β = 0.14, 95%CI = 0.10-0.18, P < .001), being male (β = 3.99, 95%CI = 2.86-5.12, P < .001), higher BMI (β = 0.13, 95%CI = 0.05-0.20, P = .002) and SG (β = 2.56, 95%CI = 1.36-3.76, P < .001) as determinants for a greater %FFML/WL.

Conclusion: Patients lost most FFM within 3 to 6 months post-surgery. Prevalence of excessive FFM loss was high, emphasizing the need for more vigorous approaches to counteract FFM loss. Furthermore, future studies should assess habitual physical activity and dietary intake shortly after surgery in relation to FFM loss.

Keywords: Bariatric surgery; Body composition; Fat-free mass.

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Conflict of interest statement

MAH Nuijten declares that she has no conflict of interest. VM Monpellier works as research coordinator at the Nederlandse Obesitas Kliniek. TMH Eijsvogels declares that he has no conflict of interest. IMC Janssen is medical director of the Nederlandse Obesitas Kliniek. EJ Hazebroek declares that he has no conflict of interest. MTE Hopman declares that she has no conflict of interest.

Figures

Fig. 1
Fig. 1
Changes in fat mass (a) and fat-free mass (b) with respect to preoperative measures up to 36 months post-surgery. Error bars reflect standard deviation (1SD). *P < 0.05 with respect to former measurement. Fat mass significantly decreased to 52.1% of preoperative fat mass at 18 months post-surgery, followed by a significant increase in fat mass. FFM significantly decreased to 14.5% of preoperative FFM at 18 months post-surgery, with no significant changes up to 36 months post-surgery. Highest rates of fat mass loss and FFM loss were observed at 3 and 6 months post-surgery
Fig. 2
Fig. 2
Weight loss with respect to preoperative weight with its proportions of fat mass loss and FFM loss. Bars reflect weight loss in kilogrammes with standard deviation. Percentages of fat mass loss and FFM loss are displayed within the bars. FM, fat mass; FFM, fat-free mass. Proportion of FFM loss of total weight loss decreased from 3 to 9 months post-surgery and subsequently increased again up to 24.7% at 36 months post-surgery
Fig. 3
Fig. 3
Prevalence of excessive FFM loss in our cohort at each measuring point based on the cutoff values of ≥ 25%, ≥ 30% and ≥ 35% FFML/WL. For each cutoff value, prevalence of excessive FFM loss decreased from 3 to 9 months post-surgery. Thereafter, prevalence increased again up to 36 months post-surgery
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