Improving adherence to weight management strategies: information length and implementation intentions

Objective: Adherence to weight management strategies may be undermined where lengthy strategy explanations limit engagement and understanding, weakening intervention efficacy. By contrast, implementation intentions have been shown to promote adherence across various health behaviours. This study investigated the impact of explanation length and implementation intentions on adherence to brief weight management strategies. Methods: Participants (n=200) with a BMI above 25 and an interest in losing weight were recruited from a commercial weight management service provider. Participants received information about one of four weight management strategies on a smartphone application in either a brief or detailed format and were asked to plan their use of the strategy with implementation intentions or were given tips on strategy use. Participants received daily prompts over a 2-week period to report whether they used their assigned strategy. Proposed moderators (need for cognition and planning skills) were measured at baseline. Results: Strategy adherence was greater with brief information (M=74%, SD=23) compared to detailed information (M=69%, SD=23), however this small effect size (d = 0.24) was not statistically significant (p=.13). There was no moderation by need for cognition (p=.25). Adherence did not differ significantly between implementation intentions (M=71%, SD=27) and tips (M=72%, SD=21; p=.73), however there was moderation by planning skills (p=.04); as predicted, adherence was greater with implementation intentions compared to tips among those with poorer planning skills. Conclusions: Shorter explanation length and implementation intentions (in poorer planners) may enhance adherence to brief weight management strategies; further investigation is required to confirm these effects.