Postoperative changes in body composition occurred asynchronously across multiple physiological domains in patients with gastric and colorectal cancer, with body weight and skeletal muscle index reaching nadir at approximately 3 months while phase angle and extracellular water ratio showed the most prominent changes on postoperative day 1.
Key Findings
Results
Body weight and skeletal muscle index (SMI) gradually declined after surgery, reaching their lowest levels at approximately 3 months postoperatively, followed by partial recovery at 6 and 12 months without complete restoration to preoperative values in several subgroups.
Study enrolled 138 patients: 61 with gastric cancer (GC) and 77 with colorectal cancer (CRC)
Assessment points included preoperative period, postoperative day 1, and 3, 6, and 12 months postoperatively
Complete restoration to preoperative values was not achieved in several subgroups by 12 months
Recovery was characterized as 'partial' at the 6- and 12-month timepoints
Results
Phase angle (PhA) declined abruptly on postoperative day 1, representing the most prominent early postoperative change in this parameter.
The decline in PhA on postoperative day 1 was described as 'abrupt', contrasting with the gradual decline seen in body weight and SMI
PhA is a bioelectrical impedance analysis parameter reflecting cellular integrity and nutritional status
Advanced-stage and chemotherapy-treated patients appeared to show slower normalization of PhA
The asynchronous timing of PhA changes distinguished it from the trajectory of SMI and body weight
Results
Extracellular water to total body water ratio (ECW/TBW) peaked on postoperative day 1, co-occurring with the abrupt decline in phase angle as the most prominent early postoperative changes.
ECW/TBW peaked at postoperative day 1, indicating acute fluid shifts and cellular stress immediately following surgery
Advanced-stage and chemotherapy-treated patients appeared to show slower normalization of ECW/TBW
ECW/TBW represents the ratio of extracellular water to total body water and reflects fluid distribution and hydration status
The simultaneous peak of ECW/TBW and nadir of PhA on day 1 formed a distinct early postoperative pattern separate from the later muscle mass trajectory
Results
Patients with low skeletal muscle mass showed persistently lower SMI values throughout the 12-month follow-up period.
Low skeletal muscle mass was identified as one of several clinically vulnerable subgroup characteristics
SMI recovery patterns were described as 'less complete' in low skeletal muscle mass patients compared to those with normal muscle mass
These findings were described as 'descriptive subgroup patterns' without formal inferential statistical comparisons reported in the abstract
The persistent deficit suggests preoperative muscle status may influence postoperative recovery trajectory
Results
Elderly patients, patients with advanced-stage disease, and chemotherapy-treated patients showed descriptive patterns suggestive of less complete recovery of SMI, PhA, and ECW/TBW.
Four vulnerable subgroups were identified: elderly patients, patients with low skeletal muscle mass, advanced-stage disease patients, and chemotherapy-treated patients
Advanced-stage and chemotherapy-treated patients appeared to show slower normalization of both PhA and ECW/TBW specifically
These patterns were explicitly characterized as 'descriptive' and 'suggestive', indicating exploratory rather than confirmatory findings
The authors noted these findings provide 'a basis for future hypothesis-driven studies'
Results
Body composition changes occurred asynchronously across multiple physiological domains following curative surgery for gastric and colorectal cancer.
The study evaluated four body composition parameters: body weight, SMI, PhA, and ECW/TBW
Early-changing parameters (PhA and ECW/TBW) showed peak changes on postoperative day 1, while body weight and SMI showed gradual decline with nadir at approximately 3 months
The asynchronous pattern was observed across both GC (n=61) and CRC (n=77) patient groups
This prospective longitudinal design captured serial changes from preoperative baseline through 12 months postoperatively
Methods
The study was a prospective longitudinal design enrolling 138 patients undergoing curative surgery for gastric or colorectal cancer with serial body composition assessments over 12 months.
138 total patients: 61 with gastric cancer and 77 with colorectal cancer
Body composition was assessed using bioelectrical impedance analysis parameters including SMI, PhA, and ECW/TBW
Measurement timepoints included preoperative baseline, postoperative day 1, and 3, 6, and 12 months after surgery
The study was described as prospective and longitudinal, aimed at describing recovery patterns rather than testing specific hypotheses
What This Means
This research suggests that the body does not recover uniformly after cancer surgery — instead, different aspects of body composition change on different timescales. In 138 patients who had surgery to remove gastric or colorectal cancer, researchers tracked four measures of body composition from before surgery through one year afterward. They found that muscle mass and body weight declined slowly, hitting their lowest point around three months after surgery before partially rebounding, while a different set of measures reflecting cellular health (phase angle) and fluid balance (ECW/TBW ratio) changed dramatically within the very first day after surgery.
This research also suggests that certain groups of patients may have a harder time recovering. Older patients, those who already had low muscle mass before surgery, those with more advanced cancer, and those who received chemotherapy all showed patterns of less complete recovery across one or more of the body composition measures studied. Notably, patients with low pre-surgery muscle mass continued to have lower muscle mass throughout the entire 12-month follow-up, suggesting that preoperative muscle status may set the ceiling for how well patients recover.
The practical implication of these findings is that monitoring a single measure of recovery at a single time point may not capture the full picture of how a patient is doing after cancer surgery. Because different body composition measures change at different times and at different rates, serial assessments using multiple measures over an extended follow-up period may be needed to fully understand postoperative recovery. The authors frame these findings as descriptive and exploratory, providing a foundation for future research to test whether targeted interventions for high-risk groups — such as pre-surgery muscle-building programs or post-surgery nutritional support — could improve recovery outcomes.
Check Your Own Numbers
Upload your bloodwork. We'll cross-reference your results against this study and 4,700 others.
Kang J, Kim S, Shin D, Kim M, Jeong W, Baek S, et al.. (2026). Asynchronous Recovery of Body Composition After Curative Surgery for Gastric and Colorectal Cancer: A Prospective Longitudinal Study.. Nutrients. https://doi.org/10.3390/nu18193172