Smoking Cessation Treatment for Smokers With Obesity

This study aims to developed an empirically validated psychological intervention protocol for smoking cessation among individuals with excess weight. Participants will be assigned to one of the two following conditions: 1) Cognitive-Behavioral Treatment (CBT) for smoking cessation + a Weight Gain Prevention module (WGP); 2) the same treatment alongside Contingency Management (CM) for smoking abstinence.

The main goals are: 1) to assess smoking abstinence rates in each condition at post-treatment and one, three, six and twelve month follow-ups, 2) to assess the effect of treatment conditions and abstinence on weight at each assessment point, 3) to analyze the potential moderating effect of individual variables: socio-demographic characteristics, severity of nicotine dependence and demand, disordered eating, impulsivity and emotional regulation.

Smoking rates are quite high among overweight or obese population. In this regard, smokers with excess weight use to report fear to quit due to post-cessation weight gain concerns, the presence of disordered eating (binge eating and emotional eating) before or during the quitting process, weight increase, relapse risk, risk of metabolic syndrome, obesity or diabetes and cardiovascular risk factors. Despite previous efforts, research is still required to assess the course of eating-related problems in smoking cessation, the impact of smoking on the onset and development of psychological and medical issues and, particularly, it is necessary to perform studies to assess the efficacy of psychological interventions for smoking cessation among individuals with excess weight. Prior evidence showed that Contingency Management (CM) techniques are adequate to reduce tobacco use and perform better than other interventions and control conditions. Nevertheless, there is a lack of research exploring the effectiveness of CM for overweight or obese smokers.The primary aim of this clinical trial is to yield data on the effectiveness of a psychological intervention for smoking cessation among individuals with excess weight. Participants will be assigned to one of the two following conditions: 1) Cognitive-Behavioral Treatment (CBT) for gradual smoking cessation + a Weight Gain Prevention module (WGP) for weight stability; 2) the same treatment alongside Contingency Management (CM) for smoking abstinence. In view to assure adequate power for achieving statistical significance, investigators carried out a priori power analysis by using the G\*Power 3.1. An estimated sample size of 120 participants would detect a medium effect size (Cohen's d = 0.3, with power (1-β) set at 0.97 and α = 05).The primary analyses derived from this clinical trial will be conducted using Statistical Package for the Social Science (SPSS) version 24 for Windows. A set of descriptive and frequency analyses will be carried out with regard to participants' characteristics. Comparisons between treatment groups in both baseline characteristics and treatment outcomes will be conducted using a set of chi-square tests for categorical variables and t-tests (two-tailed) for continuous variables.

Eligibility Criteria:
Inclusion Criteria:

* Being aged 18 or over.
* Having smoked 10 or more cigarettes/day within the last year.
* Meeting the diagnostic criteria for nicotine dependence according to the Diagnostic and Statistical Manual of Mental Disorders-5th ed. (American Psychiatric Association 2013).
* Having overweight or obesity (BMI above 25)

Exclusion Criteria:

* Not being able to attend the entire treatment.
* Being currently receiving other psychological/pharmacological treatment for smoking cessation or weight control
* Being diagnosed with a current severe psychiatric disorder, eating disorder other than Binge-Eating Disorder or Substance Use Disorder other than nicotine.
* Being pregnant, lactating or in the postpartum period
* Have any health condition that requires a specialized diet or aﬀected eating
* Participants must not be taking a medication that impacts weight