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A randomized trial comparing weight loss treatment delivered in large versus small groups
The International Journal of Behavioral Nutrition and Physical Activity
|September 25, 2014
Summary
Smaller groups led to significantly greater weight loss in obesity treatment compared to large groups. This was linked to better adherence, suggesting group size impacts behavioral intervention effectiveness.
Area of Science:
- Obesity research
- Behavioral science
- Clinical trial methodology
Background:
- Behavioral interventions for obesity are often group-based.
- The impact of group size on weight loss outcomes is not well-understood.
- This study evaluated weight changes in large versus small groups for obesity treatment.
Purpose of the Study:
- To compare the effectiveness of large group (LG) versus small group (SG) behavioral interventions for obesity.
- To determine if group size influences weight loss at 6 and 12 months.
- To explore the relationship between group size, treatment adherence, and weight loss.
Main Methods:
- 66 obese adults were randomized into LG (30 members/group) or SG (12 members/group) treatment.
- Interventions included 24 weekly sessions followed by 6 monthly contacts.
- Weight change was analyzed using a mixed-effects model.
Main Results:
- SG participants achieved significantly greater weight loss at 6 months (-6.5 kg vs. -3.2 kg) and 12 months (-7.0 kg vs. -1.7 kg) compared to LG participants.
- Adherence to treatment and self-monitoring was better in SG.
- Improved adherence fully mediated the effect of group size on weight loss.
Conclusions:
- Obesity treatment in smaller groups may lead to better weight loss and maintenance.
- Enhanced adherence in smaller groups appears to be the key mechanism.
- The efficiency of large group interventions should be weighed against the superior outcomes of smaller groups.
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