Long-term weight-loss maintenance in obese patients with knee osteoarthritis: a randomized trial.

A formula low-energy diet (LED) reduces weight effectively in obese patients with knee osteoarthritis, but the role of LED in long-term weight-loss maintenance is unclear. We aimed to determine the effect of intermittent LED compared with daily meal replacements on weight-loss maintenance and number of knee replacements over 3 y. The design was a randomized trial with participants aged >50 y who had knee osteoarthritis and a body mass index [BMI (in kg/m)] ≥30. Participants were recruited from the osteoarthritis outpatient clinic at Copenhagen University Hospital in Frederiksberg, Denmark; they had previously completed a 68-wk lifestyle intervention trial and achieved an average weight loss of 10.5 kg (10% of initial body weight). Participants were randomly assigned to either the intermittent treatment (IN) group with LED for 5 wk every 4 mo for 3 y or to daily meal replacements of 1-2 meals for 3 y [regular (RE) group]. Attention by dietitians and the amount of formula products were similar. Primary outcomes were changes in body weight and proportion of participants receiving knee replacements. Outcomes were analyzed on the intention-to-treat-population with the use of baseline-carried-forward imputation for missing data. A total of 153 participants (means ± SDs: BMI: 33.3 ± 4.6; age: 63.8 ± 6.3 y; 83% women) were recruited between June and December 2009 and randomly assigned to the IN ( = 76) or RE ( = 77) group. A total of 53 and 56 participants, respectively, completed the trial. Weight increased by 0.68 and 1.75 kg in the IN and RE groups, respectively (mean difference: -1.06 kg; 95% CI: -2.75, 0.63 kg; = 0.22). Alloplasty rates were low and did not differ (IN group: 8 of 76 participants; RE group: 12 of 77 participants; = 0.35). After a mean 10% weight-loss and 1-y maintenance, additional use of daily meal replacements or intermittent LED resulted in weight-loss maintenance for 3 y. These results challenge the commonly held assumption that weight regain in the long term is inevitable. This trial was registered at clinicaltrials.gov as NCT00938808.