Association between Self-Weighing and Percent Weight Change: Mediation Effects of Adherence to Energy Intake and Expenditure Goals

Abstract

Background

To date, no investigators have examined electronically recorded self-weighing behavior beyond nine months or the underlying mechanisms of how self-weighing may impact weight change.

Objective

1) Examine electronically recorded self-weighing behavior in a weight loss study; 2) examine the possible mediating effects of adherence to energy intake (EI) and energy expenditure (EE) goals on the association between self-weighing and weight change.

Design

This was a secondary analysis of the self-efficacy enhancement (SE) arm of the Self Efficacy Lifestyle Focus (SELF) trial, an 18-month randomized clinical trial.

Participants/setting

The study was conducted at the University of Pittsburgh (2008–2013). Overweight or obese adults with at least one additional cardiovascular risk factor were eligible.

Intervention

Participants in the SE arm were given a scale (Carematix, Inc.) and instructed to weigh at least 3 days/week or every other day. The scale date- and time-stamped each weighing episode, storing up to 100 readings.

Main outcome measures

Weight was assessed every six months. Adherence to EI goal and EE goal was calculated on a weekly basis using paper diary data.

Statistical analyses performed

Linear mixed modeling and mediation analyses were used.

Results

The sample (N=55) was 80% female, 69% Non-Hispanic White, with mean (SD) 55.0 (9.6) years old and a BMI of 33.1 (3.7) kg/m ². Adherence to self-weighing declined over time (p<0.001). From baseline to 6 months, there was a significant mediation effect of adherence to EI (p=0.02) and EE goals (p=0.02) on the association between adherence to self-weighing and percent weight change. Mediation effects were not significant during the second and third 6-month periods of the study.

Conclusions

The objectively measured adherence to self-weighing declined over 18 months. During the first six months, self-weighing directly impacted weight change and indirectly impacted weight change through changes in EI and EE.