Objective: Very-low-calorie diets (VLCDs), providing <800 kcal/d, have been used since the 1970s to induce rapid weight loss. Previous reviews of the literature have disagreed concerning the relative efficacy of VLCDs vs. conventional low-calorie diets (LCDs) for achieving long-term weight loss.
Research methods and procedures: We sought to update findings on the clinical use, safety, and efficacy of VLCDs and to perform a meta-analysis of randomized trials that compared the long-term efficacy of LCDs and VLCDs. Original research articles were retrieved by a Medline search and from prior reviews of VLCDs. Trials were included only if they were randomized comparisons of LCDs and VLCDs and included a follow-up assessment at least 1 year after maximum weight loss. Data were abstracted by both authors regarding: duration of VLCD, total length of treatment, attrition, short- and long-term weight loss, changes in weight-related comorbidities, and adverse effects.
Results: Six randomized trials were found that met inclusion criteria. VLCDs, compared with LCDs, induced significantly greater short-term weight losses (16.1 +/- 1.6% vs. 9.7 +/- 2.4% of initial weight, respectively; p = 0.0001) but similar long-term losses (6.3 +/- 3.2% vs. 5.0 +/- 4.0%, respectively; p > 0.2). Attrition was similar with VLCD and LCD regimens.
Discussion: VLCDs did not produce greater long-term weight losses than LCDs. In the United States, the use of liquid meal replacements as part of a 1000 to 1500 kcal/d diet may provide an effective and less expensive alternative to VLCDs. In Europe, VLCDs are used with less intensive medical supervision than in the United States, which reduces the cost of this approach.