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Table 1 Characteristics of intervention studies examining potential mediators/predictors of weight control, physical activity, and food intake (n = 35)

From: Successful behavior change in obesity interventions in adults: a systematic review of self-regulation mediators

Characteristics Number of studies Characteristics Number of studies
Study design (n = 35)   Intervention (n = 35)  
Trial   Aim  
NCT 6 Weight loss 15
NRCT 1 Weight maintenance 6
RCT 28 Exercise adherence 3
Arms   Health promotion 8
1 arm 6 Other 2
2 arms 18 Theoretical grounds b  
3 arms 8 SCT 23
4 or + arms 3 TTM 5
Sample size   SDT 3
<100 2 Other 8
100-199 12 N.R. 4
200-299 11 Intervention setting  
≥300 10 University 15
   Hospital/clinic 3
Participants (n = 35)   Exercise/fitness club 12
Gender   Community 3
Women only 13 Web 1
Both genders 22 Other 1
Mean age, years   Intervention length  
25-44 23 <6 months 6
45-64 11 6-12 months 16
N.R. 1 12-24 months 12
BMI   ≥24 months 1
25-29.9 2 Post-intervention follow-up (n = 11)
30-34.9 14 <6 months 1
35-39.9 4 6-12 months 5
≥40 8 12-24 months 4
N.R. 7 ≥24 months 1
Characteristics Number of studies Characteristics Number of studies
Mediation analysis (n = 10)   Outcomes  
Type of test   Weight change (n = 26)  
Regression-based 2 Short-term (<12 months) 9
P and H/bootstrap 4 Long-term (≥12 months) 17
SEM/bootstrap 4   
Mediation approach (and criteria) a Physical activity (n = 19)  
Baron and Kenny 3 Short-term (<12 months) 11
MacKinnon et al. 7 Long-term (≥12 months) 8
Shrout and Bolger 2 Self-reported (MVPA) 15
MacArthur 1 Self-reported (LPA) 2
   Self-reported (Energy Exp.) 1
Quality assessment score Objectivec, d 4
Quality score (EPHPP tool; n = 35)   
Weak 7 Food/energy intake (n = 11) e  
Moderate 15 Short-term (<12 months) 7
Strong 13 Long-term (≥12 months) 4
Quality score (Rhodes tool; n = 10) Total energy intake 3
Low 0 Fat/saturated fat 6
Moderate 10 Fruit/vegetable 7
High 0 Other (CH; protein) 1
  1. Notes: NCT, non-controlled trial; NRCT, non-randomized controlled trial (for example, a study comparing two interventions, but without a real control group); RCT, randomized controlled trial (Note: two studies referred to post hoc analyses of existing RCTs, for outcomes that were not planned originally); N.R., not reported; P and H, Preacher and Hayes mediation procedures; SEM, structural equation modeling; EPHPP, Effective Public Health Practice Project; SCT, socio-cognitive theory; TTM, transtheoretical model; SDT, self-determination theory; MVPA, moderate and vigorous physical activity; LPA, lifestyle physical activity; Energy Exp., energy expenditure. aTwo studies used more than one mediation approach. bSix studies used more than one theoretical framework. cObjective assessments included accelerometry (n = 1), pedometry (n = 1), and actual attendance to a fitness club (n = 2). dTwo of the studies also assessed self-reported physical activity. eThree studies assessed more than one outcome.