Prevention of weight regain after weight loss is a major challenge. Studies employing passive follow up of weight loss maintenance indicate that 50-80% of participants gradually regain all their lost weight and 50% of this weight regain occurs within the first year. This has led to the development of active weight loss maintenance programs which provide specific interventions to try and prevent this weight regain. To date there is no consensus or clear understanding of the components or strategies necessary for a successful weight loss maintenance intervention. Previous reviews have concluded that pharmacotherapy and group support are most effective for weight loss maintenance. However, prolonged use of pharmacotherapy for weight loss maintenance may be unsafe and providing support, whether face-to-face or by telephone contact, may be unsustainable in the longer term. Therefore, an understanding of the effectiveness of interventions with a specific dietary component for weight loss maintenance following weight loss is important, and a review focused on this strategy is required.
The primary objective of this systematic review was to assess the effectiveness of weight loss maintenance interventions that included a specific diet strategy on prevention of weight regain following weight loss.
Types of participants
Study eligibility criteria consisted of those with weight loss maintenance interventions trialed on participants who had recently lost weight, usually as part of a prior weight loss intervention study component, and with participants ≥18 years with a body mass index >24.9 kg/m2prior to weight loss. Studies were considered if the participants had existing co-morbidities associated with overweight and obesity; however, they were excluded if participants had major medical problems or psychological illness.
Types of intervention(s)
Weight loss maintenance intervention strategies considered eligible were manipulation of a specific dietary component including prescribed diets, guidelines, advice and/or support to adhere to a dietary prescription.
Types of studies
Only randomized controlled trial study designs were considered.
Types of outcomes
The primary outcome measures were weight change, body mass index change, waist circumference change and body fat change.
Published and unpublished studies in the English language from 1970 to January 2012 were identified from six electronic databases.
Methodological quality was assessed by two independent reviewers using the standardized critical appraisal instrument from the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument.
Data were extracted using the JBI data extraction form for experimental studies and included participant characteristics, intervention characteristics, study retention rates, and weight outcomes (weight change; kg or %, body mass index, waist circumference).
The impact of interventions on weight outcomes was described in a narrative format within each group of studies. The effectiveness of weight loss maintenance interventions was also assessed using the criteria of maintenance of ≥5% of initial weight loss. When studies were sufficiently similar and results were reported as either change scores or final values, and presented as means with standard deviations, data were pooled in a meta-analysis.
Sixty-four articles representing 56 studies were included in this review. Twenty seven studies prescribed a diet intervention, 11 meal replacements, two re-feeding time and type, and 16 support delivery mode interventions. Of the 56 studies, only 14 reported significant results for weight loss maintenance (Diet n=6, Meal replacements, n=1, Re-feeding n=1, Support delivery mode n=6).
Currently there are many weight loss maintenance interventions being trialed but few have been found to be effective at maintaining >5% of initial weight loss. Whether this is due to the intervention itself being ineffective or simply the lack of reporting of this outcome, it is clear that more studies are needed to address this issue.
Implications for practice
To facilitate long-term maintenance of lost weight, health professionals need to advise clients that a specific weight loss maintenance strategy is needed following initial weight loss. Further evidence is required in terms of which intervention components are most effective.
Implications for research
To strengthen the current evidence base on weight loss maintenance interventions, additional high quality randomized controlled trials that closely adhere to the Consolidated Standards of Reporting Trials guidelines are required. Studies investigating different approaches to achieving a long-term reduction in energy intake are needed along with evaluation of different approaches to providing support for behavior change during weight loss maintenance.