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05-10-2011 | Cardiometabolic | Article

Little evidence for frequently used weight loss method


Free abstract

MedWire News: UK researchers say there is little evidence that a frequently used lifestyle modification program is effective for helping obese and overweight people lose weight.

The transtheoretical model stages of change (TTM SOC) model was found to have limited impact on weight loss, about 2 kg or less, and there was "no conclusive evidence" for sustainable weight loss.

"TTM describes the sequential behavior change in an individual from an unhealthy behavior to a healthy one," explain Nik Tuah (Imperial College London) and co-authors.

"Studies have shown that the TTM SOC can be used to plan dietary interventions, for short term weight loss amongst overweight and obese individuals over a minimum of three months." However, "the effectiveness of TTM for weight loss beyond 1 year is inconsistent," they say.

To assess the effectiveness of TTM-based dietary and physical activity interventions for sustained weight loss in overweight (body mass index [BMI] 25-30 kg/m2) and obese (BMI >30 kg/m2) adults, the authors searched the literature for randomized controlled clinical trials using TTM SOC as a model, theoretic framework, or guideline in designing lifestyle modification strategies.

A total of five studies, involving 3910 participants, met the inclusion criteria. Of the participants, 1834 were randomly allocated to intervention groups and 2076 to control groups. The trials varied in length of intervention (from 6 weeks to 24 months), with a median length of 9 months.

Tuah et al report that the use of TTM SOC resulted in "minimal weight loss" of about 2 kg or less, and there was "minimal evidence" for sustainable weight loss amongst participants.

However, other significant positive outcomes were noted, such as change in physical activities, behavior, and dietary intake.

Weight gain was among the adverse events reported, notes the team, and the trials did not report other important outcomes such as health-related quality of life, morbidity, and cost.

"The impact of TTM SOC in weight loss management may depend on how it is used in combination with other strategies," comment Tuah et al. "In practice, TTM SOC must be applied with caution because it has a variable impact depending on how it is used and with what other factors," they conclude.

The findings were published in the Cochrane Database of Systematic Reviews.

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By Nikki Withers