Association of Weight Cycling with MRI-based Thigh Muscle Quality and Knee-adjacent Obesity: Osteoarthritis Initiative Data.

Background Repeated episodes of weight loss and regain, termed "weight cycling," may be associated with sarcopenia. Purpose To compare 48-month changes in MRI-based thigh muscle volume, proportion of intermuscular adipose tissue (IMAT), and knee-adjacent subcutaneous adipose tissue (KaSAT) thickness between weight-stable weight cyclers and weight-stable noncyclers. Materials and Methods In this secondary analysis of Osteoarthritis Initiative data conducted from February 2004 to October 2015, participants with less than a 5% cumulative weight change from baseline to the 48-month follow-up were classified as weight cyclers or noncyclers based on the root mean square error of individual regression models of annual body mass index measurements. The outcomes included changes in MRI-based thigh muscle volume, proportion of IMAT, and KaSAT thickness of the right thigh and knee between baseline and follow-up. Linear regression models were used to evaluate the associations between weight cycling and the outcomes; the models were adjusted for demographic, anthropometric, metabolic, and lifestyle factors. Results A total of 1433 participants were included (mean age, 60.9 years ± 8.9 [SD]; 750 female). Weight cyclers (n = 77) had greater muscle volume loss than noncyclers (n = 1356) (-3.71% [95% CI: -6.08, -1.35] vs -1.03% [95% CI: -2.62, 0.57]; P = .003). There was no evidence of a difference in IMAT proportion change (weight cyclers: 2.55% [95% CI: 0.70, 4.40]; noncyclers: 2.61% [95% CI: 1.36, 3.87]; P = .93) or in KaSAT thickness change (weight cyclers: 12.30% [95% CI: 6.26, 18.30]; noncyclers: 12.20% [95% CI: 8.12, 16.20]; P = .97). Conclusion In participants who maintained stable weight over 48 months, weight cycling was associated with an increased loss of MRI-based thigh muscle volume, whereas no evidence of a difference was found for changes in IMAT proportion. The KaSAT thickness increased in all participants, but there was no evidence of a difference between weight cyclers and noncyclers. © RSNA, 2026 Supplemental material is available for this article. See also the editorial by Roemer in this issue.