Sarcopenia, Muscle Mass and Protein Intake in Adults Older Than 65 Years After Earlier Bariatric Surgery

Abstract

Background: Metabolic and bariatric surgery (MBS) is a proven treatment for obesity. Yet weight loss is accompanied by loss of muscle which may predispose to sarcopenia. The prevalence of low muscle mass in older adults after MBS remains unexplored, even though this group is more vulnerable to sarcopenia.

Methods: This cross-sectional study investigated sarcopenia and low muscle mass by comparing adults older than 65 years with previous MBS (BAR) to patients following nonsurgical obesity management (CON). A sample size of 100 was estimated from appendicular lean mass (ALM) in a similar study in younger adults. Patients were recruited from the University Hospitals Leuven Obesity Clinic, Belgium. Study assessments included dual-energy X-ray absorptiometry, handgrip, short battery of physical performance, blood sampling and self-reported dietary intake. Sarcopenia was defined according to the European Working Group on Sarcopenia in Older People (EWGSOP1) criteria using obesity-specific cut-off points and sarcopenic obesity by the European Society for Enteral and Parenteral Nutrition (ESPEN) and the European Association of the Study of Obesity (EASO) consensus definition. Main endpoints were sarcopenia and ALM normalized to body mass index (%ALM/BMI). A multiple linear regression model was fitted to predict ALM.

Results: We included 50 participants per group (male, BAR 40%, CON 35%). BAR participants were older (68.3 ± 3.2 years vs. 70.7 ± 3.9, p < 0.01), and more had diabetes (52% vs. 28%). BAR lost more bodyweight after MBS than CON following nonsurgical treatment (BAR 31.6 ± 9.5% vs. CON 12.1 ± 8.42%, p < 0.001). Fat free mass (FFM) was lower for BAR than for CON, but %ALM/BMI was not different (64.7 ± 18.1% vs. 62.6 ± 15.8, p = 0.53). Twenty percent to 56% of participants had low muscle mass, depending on sex and criterium, but only 3% met the criteria for sarcopenia and 9% for sarcopenic obesity. Protein intake tended to be higher in BAR than in CON (1.36 ± 0.36 g/kg FFM/day vs. 1.25 ± 0.27, p = 0.09). Most participants did not meet optimal protein intake recommendations after BMS nor for older adults in general. In the linear regression model, muscle mass increased with male sex, BMI, adiposity and protein intake and decreased with age, (adjusted R² 0.80). Neither BAR compared to CON nor surgery type or other clinical parameters influenced muscle mass.

Conclusion: Older adults with previous MBS were not more likely to develop sarcopenia than older adults following nonsurgical treatment. Rather, age, adiposity and low protein intake lower muscle mass, predisposing to sarcopenia.

Trial registration: clinicaltrials.gov identifier: NCT05582668.

Keywords: bariatric surgery; body composition; dietary proteins; obesity; sarcopenia; skeletal muscle.

FIGURE 1

Flow diagram of study recruitment.

FIGURE 2

Protein intake by group compared to protein recommendations. All bars are mean for the groups. (a) Total dietary intake compared to minimum recommendations after MBS of 60 g/day. (b) Intake/actual bodyweight (ABW) compared to recommended intake for older adults of > 1 g/kg/day. (c) Intake/ideal bodyweight (IBW) compared to recommended intakes of 1.5 g/kg/IBW recommendation after MBS. (d) Intake/fat free mass compared to EAR of 1.6 g/kg FFM for older adults determined by the indicator amino acid oxidation (IAAO) method.

FIGURE 3

Linear model effects on appendicular lean mass (ALM) sex. BAR vs. CON did not improve model fit but is included visually for comparison purposes. Shaded grey areas are 95% confidence intervals. Plot d depicts the effect of BMI on the x‐axis and the interaction effect between BMI and fat proportion through shading of data points.