Effects of a Web-Based, Evolutionary Mismatch-Framed Intervention Targeting Physical Activity and Diet:a Randomised Controlled Trial

BackgroundThis study sought to test the effectiveness of a 12-week, novel online intervention (Evolife) aiming to increase physical activity level (PAL) and reduce energy intake (EI) among overweight/obese adults. The intervention used an evolutionary mismatch message to frame health information in an engaging way, incorporating evidence-based behaviour change techniques to promote autonomous motivation, self-efficacy and self-regulatory skills.MethodMen and women aged 35–74 years with a BMI of 25–40 kg/m2 were eligible. Participants were randomised to receive either the intervention (comprising a face-to-face introductory session, 12 weeks’ access to the Evolife website and a pedometer) or a control condition (face-to-face introductory session and NHS online health resources). PAL was measured objectively and EI was self-reported using 3-day weighed food records. Secondary measures included BMI, waist circumference and blood pressure.ResultsSixty people met inclusion criteria; 59 (30 intervention) completed the trial (mean age = 50; 56% male). Differences between groups’ change scores for PAL and EI were of small effect size but did not reach significance (d = 0.32 and d = − 0.49, respectively). Improvements were found in both groups for PAL (int: d = 0.33; control: d = 0.04), EI (int: d = − 0.81; control: d = − 0.16), waist circumference (int: d = − 0.30; control: d = − 0.17) and systolic blood pressure (int: d = − 0.67; control: d = − 0.28).ConclusionThe intervention did not lead to significantly greater improvement in PAL or reduction in EI than a minimal intervention control, although the changes in the intervention group were of meaningful effect size and comparable with positive outcomes in larger intervention trials.Trial RegistrationThis trail was registered on www.clinicaltrials.gov on 16 January 2017 (appeared online 26 January 2017), reference NCT03032731