An Exploratory Analysis of Patterns of Weight Change in a Post-Cessation Weight Management Trial

INTRODUCTION: Previous research investigating trajectories of weight change after quitting smoking has been limited due infrequent weight measurements; newer e-scales data facilitate more frequent weight measurement. We explored rate of weight gain and when weight change stabilized via secondary data analyses from the post-cessation weight management-focused "Fit & Quit" trial.

METHODS: After completion of one of three randomized weight intervention conditions, all participants located in the United States completed a behavioral smoking cessation intervention with varenicline pharmacotherapy in 2018-2022. Participants were asked to weigh daily on study-provided e-scales throughout the 12-month study. Mixed-effects models were performed to characterize weight change over time and to test whether the intervention condition or gender impacted the temporal rate of weight change (n=132).

RESULTS: Rate of weight change in the first month after quitting smoking was most rapid, at +0.0111 kg/day. To identify when weight stabilized, we use a fifth-degree polynomial model and found that participants began gaining weight immediately after quitting, with the rate of gain peaking around the 21st day. Weight gain continued at a lower, but still statistically significant, rate until approximately 70 days after cessation, after which the weight began to plateau. All intervention condition groups had similar rates of weight gain, with no gender differences in the rate of weight gain.

CONCLUSIONS: The first month after quitting smoking was a particularly vulnerable time period for weight gain. Future programs combining weight management and smoking cessation should emphasize maintenance of weight management strategies within the first month after quitting smoking.

IMPLICATIONS: Future post-cessation weight management programs should priorize maintenance of weight management strategies within the first month after quitting smoking, regardless of the type of weight management strategy or the gender of the participants. Studies examining post-cessation weight gain should ensure measurement of weight gain for at least 2-3 months after quitting smoking.