Long-Term Body Composition Changes in Women Following Roux-en-Y Gastric Bypass Surgery

Abstract

Background: Although most individuals experience successful weight loss following Roux-en-Y gastric bypass (RYGB), weight regain is a concern, the composition of which is not well documented. Our aim was to evaluate changes in body composition and handgrip strength as a measure of functional status in participants from a previous 1-year post-RYGB longitudinal study who had undergone RYGB approximately 9 years prior.

Methods: Five women from an original larger cohort were monitored pre-RYGB and 1.5 months, 6 months, 1 year, and 9 years post-RYGB. Body composition was assessed at all time points using dual energy x-ray absorptiometry and multiple dilution. Handgrip strength was measured using a digital isokinetic hand dynamometer (Takei Scientific Instruments, Ltd, Tokyo, Japan).

Results: Mean time to final follow-up was 8.7 years. Lean soft tissue (LST) loss over the ~9-year period was on average 11.9 ± 5.6 kg. Compared with 1-year post-RYGB, 9-year LST was 4.4 ± 3.0 kg lower ( P = .03). Fat-free mass decreased over the 9-year period by 12.6 ± 5.8 kg. Mean fat mass (FM) decreased from 75.4 ± 22.6 kg pre-RYGB to 35.5 ± 21.5 kg 1 year post-RYGB but then trended toward an increase of 8.6 ± 7.0 kg between 1 year and 9 years post-RYGB ( P = .053). Loss of LST was correlated with loss of handgrip strength ( r = 0.64, P = .0005).

Conclusion: The continued loss of lean mass associated with decreased handgrip strength occurring with long-term trend toward FM regain post-RYGB is concerning. The loss of LST and functional strength carries particular implications for the aging bariatric population and should be investigated further.

Keywords: Roux-en-Y gastric bypass; bariatric; dual-energy x-ray absorptiometry; fat-free mass; handgrip strength; lean body mass; lean tissue; obesity.

FIGURE 1

Changes in DXA measured tissue compartments after RYGB by individual including (A) lean soft tissue, (B) fat free mass, (C) total bone mass, and (D) DXA fat mass. Abbreviations: RYGB, Roux-en-Y gastric bypass; DXA, dual energy X-ray absorptiometry; mo, month; LST, lean soft tissue; FFM, fat free mass; FM, fat mass; BMC, bone mineral content. Time points are baseline (pre-RYGB) and 1.5-months, 6-months, 1-year, and 9-years after RYGB surgery. See Table 1 for mean values and significance.

FIGURE 2

Changes in handgrip strength after Roux-en-Y gastric bypass (RYGB) surgery are correlated with changes in lean soft tissue measured by DXA. (A) Changes in handgrip force over time by individual, (B) correlation between lean soft tissue and handgrip force, (C) handgrip force by age compared to manufacturer normal values by age. Abbreviations: DXA, dual energy X-ray absorptiometry; mo, month. Time points are baseline (pre-RYGB) and 1.5-months, 6-months, 1-year, and 9-years after RYGB surgery. Normal handgrip strength values derived from handgrip device manufacturer (Model T.K.K., Grip D, Takei Scientific Instruments, Ltd. Japan).

FIGURE 3

Comparison between methods for assessment of (A) fat mass, and (B) fat free mass 9-years post-Roux-en-Y gastric bypass (RYGB) surgery. Abbreviations: 4-comp, 4-component model calculated from density by air displacement plethysmography (ADP) using the BOD POD instrument, total body water (TBW) by deuterium dilution, and total bon mineral content (BMC) by dual-energy X-ray absorptiometry (DXA) using the following equation: Fat Mass, kg = 2.747 × (body volume, l) – 0.7145 × (TBW, l) + 1.4599 (BMC, kg) – 2.0503 × (body weight, kg).