Background: Successful weight loss and maintenance are challenging, underscoring the importance of
understanding mediators of short and longer-term success. Factors such as disinhibition and restraint
have been linked with unhealthy eating patterns, but also with successful weight control. Several
dimensions of restraint (i.e., flexible, rigid) and disinhibition (i.e., internal, external) have been identified.
These analyses examine whether subscale dimensions of restraint, disinhibition and hunger are mediators
of weight loss in women enrolled in a randomized clinical trial of a commercial weight loss program.
Method: Adult women (n=442) were randomized to one of three treatment arms, Jenny Craig (JC)
Centre-based, JC Direct (telephone-based), and usual care (UC) and are being followed for 24 months.
Sub-scales from the Eating Inventory, including Total, Internal and External Disinhibition, Total, Flexible,
and Rigid Restraint, and Total, Internal Locus and External Locus Hunger, are examined as mediators of
6- and 12-month weight change.
Results: Treatment group weight change differences were observed at 6 (JC=-8.9 kg (sd=5.0) vs UC=-3.1
kg (sd=5.0), p < .005) and 12 months (JC=-9.9 kg (sd=7.6) vs UC = -2.8 kg (sd=6.7), p < .0003). External
disinhibition and total, rigid, and flexible restraint were significant mediators of 6-month weight change.
Significant mediators of 12-month weight change included total (B=-0.77), flexible (B=-.346), and rigid
(B=-.086) restraint.
Conclusions: Results suggest that changes in external disinhibition, and multiple aspects of restraint are
important mediators of weight loss. Future analyses will examine the importance of these constructs for
long-term weight loss maintenance.