Relationship of exercise program participation with weight loss in adults with severe obesity: assessing psychologically based mediators.
BACKGROUND
Although exercise is related to weight loss, minimal energy expenditures typical in deconditioned persons explain only small portions of this reduction. Thus, it has been suggested that exercise-induced changes in psychological variables associated with appropriate eating may be mediators.


METHODS
Adults with obesity (N = 106; Mean BMI = 42.0; SD = 6.0 kg/m), volunteering for a cognitive-behavioral exercise support program and group nutrition information, were assessed on overall mood, self-efficacy for controlled eating, self-regulation skills usage for appropriate eating, recalled volume of physical activity, body mass index (BMI), and waist circumference at baseline and at month six.


RESULTS
All within-subject changes were significant (P < 0.001) and as expected, changes in volumes of physical activity were significantly related to BMI (β = -0.52) and waist circumference (β = -0.63) changes. These relationships were partially mediated by changes in self-efficacy and self-regulation scores. Mediation of mood changes did not, however, reach statistical significance.


CONCLUSIONS
In severely obese persons initiating behaviorally supported exercise, weight loss may be better accounted for by changes in psychological predictors of improved eating such as self-efficacy and self-regulation than by direct energy expenditure. Implications for weight loss theory development and clinical applications were discussed.
Annesi
James J
JJ
YMCA of Metropolitan Atlanta, Atlanta, GA; and Southern Regional Health System, Riverdale, GA 30303, USA. jamesa@ymcaatlanta.org
Gorjala
Srinivasa
S
D000328:Adult; D000339:Affect; D003071:Cognition; D004038:Diet, Reducing / Q000523:psychology*; D015444:Exercise / Q000523:psychology*; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D015999:Multivariate Analysis; D009767:Obesity, Morbid / Q000523:psychology / Q000534:rehabilitation*; D011582:Psychological Theory; D020377:Self Efficacy; D012944:Social Support; D014481:United States; D015431:Weight Loss