Improved confidence in performing nutrition and physical activity behaviours mediates behavioural change in young adults: Mediation results of a randomised controlled mHealth intervention.
The burden of weight gain disproportionally affects young adults. Understanding the underlying behavioural mechanisms of change in mHealth nutrition and physical activity interventions designed for young adults is important for enhancing and translating effective interventions.



First, we hypothesised that knowledge, self-efficacy and stage-of-change for nutrition and physical activity behaviours would improve, and second, that self-efficacy changes in nutrition and physical activity behaviours mediate the behaviour changes observed in an mHealth RCT for prevention of weight gain.



Young adults, aged 18-35 years at risk of weight gain (n = 250) were randomly assigned to an mHealth-program, TXT2BFiT, consisting of a three-month intensive phase and six-month maintenance phase or to a control group. Self-reported online surveys at baseline, three- and nine-months assessed nutrition and physical activity behaviours, knowledge, self-efficacy and stage-of-change. The mediating effect of self-efficacy was assessed in multiple PROCESS macro-models for three- and nine-month nutrition and physical activity behaviour change.



Young adults randomised to the intervention increased and maintained knowledge of fruit requirements (P = 0.029) compared to controls. Intervention participants' fruit and takeaway behaviours improved to meet recommendations at nine months, with a greater proportion progressing to action or maintenance stage-of-change (P < 0.001 and P = 0.012 respectively) compared to controls. Intervention participants' vegetable and physical activity behaviours did not meet recommendations, thereby halting progress to action or maintenance stage-of-change. Indirect effects of improved nutrition and physical activity behaviours at three- and nine-months in the intervention group were explained by changes in self-efficacy, accounting for 8%-37% of the total effect.



This provides insights into how the mHealth intervention achieved part of its effects and the importance of improving self-efficacy to facilitate improved eating and physical activity behaviours in young adults.
School of Life and Environmental Sciences, Charles Perkins Centre, University of Sydney, NSW 2006, Australia. Electronic address: stephanie.partridge@sydney.edu.au.
Stephanie R
SR
Partridge
Sydney School of Public Health, Charles Perkins Centre, University of Sydney, NSW 2006, Australia. Electronic address: kevin.mcgeechan@sydney.edu.au.
Kevin
K
McGeechan
Sydney School of Public Health, Charles Perkins Centre, University of Sydney, NSW 2006, Australia. Electronic address: adrian.bauman@sydney.edu.au.
Adrian
A
Bauman
Sydney School of Public Health, Charles Perkins Centre, University of Sydney, NSW 2006, Australia. Electronic address: philayrath.phongsavan@sydney.edu.au.
Philayrath
P
Phongsavan
School of Life and Environmental Sciences, Charles Perkins Centre, University of Sydney, NSW 2006, Australia. Electronic address: margaret.allman-farinelli@sydney.edu.au.
Margaret
M
Allman-Farinelli
D000293:Adolescent; D000328:Adult; D004032:Diet; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D015438:Health Behavior; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D008297:Male; D009752:Nutritional Status; D010349:Patient Compliance; D020377:Self Efficacy; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D017216:Telemedicine; D016896:Treatment Outcome; D015430:Weight Gain; D015431:Weight Loss; D055815:Young Adult
Behaviors; Nutrition; Obesity; Prevention; Self-efficacy; Young adults; mHealth