Planning to lose weight: randomized controlled trial of an implementation intention prompt to enhance weight reduction among overweight and obese women.
OBJECTIVE
The trial investigates the effects of augmenting an established weight-reduction intervention with implementation intention prompts.


METHODS
Fifty-five overweight or obese women (ages 18 to 76 years; body mass index from 25.28 to 48.33) enrolled in a commercial weight reduction program were randomly assigned to either an implementation intention prompt or a control condition. Data were collected twice, with a time gap of 2 months.


METHODS
The primary outcome was participants' change in weight and body mass index from preintervention to follow-up.


RESULTS
Repeated measures analysis of variance revealed a significant Time = Condition interaction: On average, implementation intention prompt participants lost 4.2 kg (95% confidence interval = 3.19, 5.07), whereas control participants lost 2.1 kg (95% confidence interval = 1.11, 3.09). The change in frequency of planning mediated the effects of the intervention on weight and body mass index change.


CONCLUSIONS
Among obese or overweight women participating in a commercial weight loss program, those who learn to form implementation intentions can achieve greater weight reduction. Planning facilitation is a key mechanism explaining enhanced weight loss generated by implementation intention formation.
Luszczynska
Aleksandra
A
Department of Psychology, University of Sussex, Falmer, ESX, England. al85@sussex.ac.uk
Sobczyk
Anna
A
Abraham
Charles
C
D000293:Adolescent; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D035061:Control Groups; D004038:Diet, Reducing / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D015438:Health Behavior; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D033182:Intention; D008875:Middle Aged; D009043:Motor Activity; D009752:Nutritional Status; D009765:Obesity / Q000178:diet therapy*; D010934:Planning Techniques; D011615:Psychotherapy, Group / Q000379:methods; D012944:Social Support; D011795:Surveys and Questionnaires; D015431:Weight Loss