Intermittent versus on-demand use of a very low calorie diet: a randomized 2-year clinical trial.

OBJECTIVES: To compare two different very low calorie diet (VLCD)-based weight maintenance strategies. DESIGN AND SETTING: A randomized 2-year clinical trial performed at the Department of Body Composition and Metabolism, Sahlgrenska University Hospital, Sweden. SUBJECTS: A total of 334 patients, body mass index (BMI) >30 kg m-2, aged 18-60 years. INTERVENTIONS: All the patients started with 16 VLCD weeks. Subjects in the intermittent group were then scheduled to use VLCD for 2 weeks every third month, whilst patients in the on-demand group were instructed to use VLCD whenever their body weight passed an individualized cut-off level. Irrespective of the treatment group, all the subjects were recommended a hypocaloric diet during VLCD-free periods. MAIN OUTCOME MEASURES: Changes in body weight, body composition, anthropometric variables and cardiovascular risk factors. RESULTS: Completers in both groups maintained highly significant weight losses after 2 years: 7.0 +/- 11.0 kg (6.2 +/- 9.5%) in the intermittent group and 9.1 +/- 9.7 kg (7.7 +/- 8.1%) in the on-demand group (P < 0.001, ns between groups). Male completers in the on-demand group lost significantly more weight than men in the intermittent group, 14.5 +/- 11.0 kg vs. 4.0 +/- 10.5 kg, respectively (P < 0.01). Most cardiovascular risk factors improved during the first year, whilst anthropometric measures, insulin, HDL- and LDL-cholesterol were also significantly improved after 2 years of treatment. CONCLUSION: Clinically significant weight reductions were achieved after 2 years of VLCD-based treatment. The structure of VLCD treatment during the maintenance phase did not affect weight loss in the total study population, whilst male subjects might benefit from the VLCD on-demand strategy.