Effectiveness And Influencing Factors Of Body Fat Reduction Intervention Program For Adolescents Based On Cross-lagged Panel Model

PurposeThe first purpose of this study is to explore the intervention effects and long-term effects of fat loss intervention on adolescent morphology,exercise capacity,exercise self-efficacy,self-esteem,and moderate physical activity using a comprehensive intervention model that improves the home-school integrated mode.The second purpose is to investigate the influencing factors of changes in body fat percentage in intervention phase and follow-up phase.MethodsThe research subjects were 100 middle school students(49 Males,51 Females)in Beijing,who were randomly divided into control group and experimental group.Before the intervention,all subjects went through the process of collecting indicators such as body composition and exercise capacity testing questionnaire filling.The intervention group received three times a week of exercise intervention(resistance training from4:30 pm to 5:00 pm and aerobic exercise from 5:00 pm to 5:30 pm),one health education every two weeks,and calorie restriction intervention(guidance on semi-free diet with calorie intake limited to within 75%of total consumption,record of calories and food types by parents and regular checks).The control group did not receive any intervention or restriction.The total intervention period was 12 weeks,and all subjects underwent post-intervention testing after stopping the intervention and follow-up testing 12 weeks after stopping the intervention,respectively.The testing indicators include age,height,weight,lean body mass,body fat mass,body fat percentage,BMI,vital capacity,vital capacity/body weight ratio,exercise self-efficacy,self-esteem,moderate-to-vigorous physical activity(MVPA),50m run,kneeling plank support,kneeling push-up,standing long jump,4*10m shuttle run,supine lift,and 1000m/800m run.Statistical analysis was performed using SPSS26.0,and paired samples T-test and independent samples T-test were used to compare data between different groups and before and after intervention.A stratified regression model was used to evaluate the influencing factors of intervention effects and long-term effects,and a cross-lagged model was constructed using AMOS25.0 to determine causality.ResultsA total of 98 subjects completed the entire study and provided complete data,including 49 in the intervention group(25 males and 24 females)and 49 in the control group(23 males and 26 females).(1)After 12 weeks of intervention,the intervention group showed significant improvements in weight,BMI,lean body mass,body fat mass,body fat percentage,female 50m sprint,kneeling push-ups,supine lifts,vital capacity,male 1000m run,male self-esteem,exercise self-efficacy,and MVPA compared to baseline(P=0.000).Follow-up after 12 weeks found that weight,BMI,lean body mass,body fat mass,and body fat percentage increased compared to the end of the intervention(P=0.000),and the increase in the intervention group was higher than in the control group(P=0.000);the increase in weight,BMI,body fat mass,and body fat percentage for both males and females in the intervention group was significantly higher than in the control group(P=0.000).(2)The fitting degree of the influence factor model on body fat percentage change was good and statistically significant even after controlling for age and gender.During the intervention stage,changes in the intervention group’s body fat percentage were influenced by changes in self-esteem(β=-0.217,P=0.000),MVPA(β=-0.144,P=0.019),and baseline body fat percentage(β=-0.066,P=0.061),R~2=0.608;changes in body fat percentage in the control group were influenced by baseline MVPA(β=-0.206),body fat percentage(β=-0.095),exercise self-efficacy(β=-0.074),and self-esteem(β=-0.092),R~2=0.401.The stratified regression model(R~2=0.859)for body fat percentage in the intervention group during follow-up showed that lower self-esteem(β=-0.107)and decreased body fat percentage during the intervention period(β=-0.107)were positively correlated with an increase in body fat percentage.(3)The cross-lagged model showed no causal relationships between exercise self-efficacy,MVPA,self-esteem,and body fat percentage in the control group at any stage,indicating poor fit.In the intervention group,there were no causal relationships between self-esteem and body fat percentage.During the intervention stage,MVPA positively predicted body fat percentage to a moderate extent(β=0.875,P=0.000),while during follow-up,changes in exercise self-efficacy negatively predicted body fat percentage to a small extent(β=-0.250,P=0.000),and changes in MVPA negatively predicted body fat percentage to a large extent(β=-0.512,P<0.01).(4)The changes in body fat percentage(β=0.142),MVPA(β=-2.035),and exercise self-efficacy(β=-1.97)measured after the intervention significantly and negatively affected the rate of decline in fat loss effectiveness.Conclusion:The 12-week fat loss intervention significantly increased adolescents’exercise quality,self-esteem,exercise self-efficacy,and MVPA based on the reduction in body fat percentage,and the increase in self-esteem and MVPA was associated with the increase in the intervention effect,and the increase in exercise self-efficacy and self-esteem was also associated with the reduction in body fat percentage in the control group without the intervention.The fat loss effect faded to different degrees 12 weeks after the termination of the intervention.The higher the obesity level of the adolescents,the greater the reduction in body fat percentage after the intervention and the fading of the effect after stopping the intervention,and the higher the increase in MVPA and exercise self-efficacy,the lower the rate of fat loss effectiveness fading.Adolescents should maintain good exercise habits and psychological status to avoid the fading effect of fat loss.