Low Carbohydrate and Moderately Fat-Reduced Diets Similarly Affected Early Weight Gain in Varenicline-Treated Overweight or Obese Smokers

Contingency management for smoking cessation for individuals with overweight or obesity: A randomized controlled trial

BACKGROUND

Interventions for quitting smoking and weight control among individuals with excess weight are scarce. Our study evaluated the effectiveness of cognitive behavioral therapy (CBT) plus contingency management (CM) in this population, and examined whether CM for smoking cessation improved CBT treatment outcomes at end of treatment (EOT) and at 1-, 3-, 6-, and 12-month follow-ups (FU).

METHODS

In an 8-week randomized clinical trial, 120 adults who smoke with overweight or obesity (54.16% females; MBMI = 31.75 ± 4.31) were randomly assigned to CBT for both quitting smoking and weight control (n = 60) or the same treatment plus CM for smoking cessation (n = 60). Outcome variables were compared (i.e., treatment completion, smoking abstinence, weight change and secondary outcomes).

RESULTS

At EOT, the CBT + CM group achieved 78.33% 7-day point-prevalence abstinence rates compared to 61.67% in the CBT group (p = .073), and rates declined over time (12-month FU: 18% vs 12%). Participants who attained abstinence weighed more compared to baseline at EOT (Mkg = 1.07; SD = 1.88) and over time (12-month FU: Mkg = 4.19; SD = 4.31). No differences were found between the two groups in outcome variables.

CONCLUSIONS

Both interventions were effective in promoting abstinence and reducing tobacco use over time. Combining CBT with CM for smoking cessation did not improve treatment outcomes in individuals with overweight or obesity compared to CBT only. Future studies should evaluate whether implementing CM for weight maintenance helps control post-cessation weight gain in this population.

"Healthier health in more ways than one": Perspectives on a program for changing both smoking and obesity-related health behaviors

INTRODUCTION

Individuals with obesity who smoke cigarettes have increased risk of morbidity and mortality. The goal of the current study was to inform the development of a multiple health behavior change intervention designed to facilitate smoking cessation while also targeting weight gain.

METHODS

Four qualitative focus groups were conducted with individuals who smoked cigarettes and had overweight or obesity (n = 16) to explore the combined effects of smoking and obesity, past attempts to quit smoking or lose weight, and preferences for a combined health intervention.

RESULTS

Focus groups converged on five themes including: the interactive effects of weight and smoking; lack of experience with evidence-based weight loss approaches; a desire and expectation to lose weight quickly; rapid weight gain during past attempts at smoking cessation; and interest in a multiple health behavior change intervention with weight management preceding smoking cessation and an emphasis on planning for the future and receiving encouragement and support.

CONCLUSIONS

Groups provided insight into key topics to highlight in a combined intervention and key issues that have interfered with success in both domains.

Nicotine affects mitochondrial structure and function in human airway smooth muscle cells

Exposure to cigarette smoke and e-cigarettes, with nicotine as the active constituent, contributes to increased health risks associated with asthma. Nicotine exerts its functional activity via nicotinic acetylcholine receptors (nAChRs), and the alpha7 subtype (α7nAChR) has recently been shown to adversely affect airway dynamics. The mechanisms of α7nAChR action in airways, particularly in the context of airway smooth muscle (ASM), a key cell type in asthma, are still under investigation. Mitochondria have garnered increasing interest for their role in regulating airway tone and adaptations to cellular stress. Here mitochondrial dynamics such as fusion versus fission, and mitochondrial Ca2+ ([Ca2+]m), play an important role in mitochondrial homeostasis. There is currently no information on effects and mechanisms by which nicotine regulates mitochondrial structure and function in ASM in the context of asthma. We hypothesized that nicotine disrupts mitochondrial morphology, fission-fusion balance, and [Ca2+]m regulation, with altered mitochondrial respiration and bioenergetics in the context of asthmatic ASM. Using human ASM (hASM) cells from nonasthmatics, asthmatics, and smokers, we examined the effects of nicotine on mitochondrial dynamics and [Ca2+]m. Fluorescence [Ca2+]m imaging of hASM cells with rhod-2 showed robust responses to 10 μM nicotine, particularly in asthmatics and smokers. In both asthmatics and smokers, nicotine increased the expression of fission proteins while decreasing fusion proteins. Seahorse analysis showed blunted oxidative phosphorylation parameters in response to nicotine in these groups. α7nAChR siRNA blunted nicotine effects, rescuing [Ca2+]m, changes in mitochondrial structural proteins, and mitochondrial dysfunction. These data highlight mitochondria as a target of nicotine effects on ASM, where mitochondrial disruption and impaired buffering could permit downstream effects of nicotine in the context of asthma.NEW & NOTEWORTHY Asthma is a major healthcare burden, which is further exacerbated by smoking. Recognizing the smoking risk of asthma, understanding the effects of nicotine on asthmatic airways becomes critical. Surprisingly, the mechanisms of nicotine action, even in normal and especially asthmatic airways, are understudied. Accordingly, the goal of this research is to investigate how nicotine influences asthmatic airways in terms of mitochondrial structure and function, via the a7nAChR.

Pilot randomized trial of cognitive-behavioral treatment plus contingency management for quitting smoking and weight gain prevention among smokers with overweight or obesity

BACKGROUND

Post-cessation weight gain is a risk factor for relapse among quitters. The primary study aim was to evaluate, among smokers with overweight or obesity, the feasibility and acceptability of a cognitive-behavioral treatment (CBT) plus contingency management (CM) for quitting smoking and weight control. The secondary aim was to examine preliminary tobacco abstinence and weight change outcomes.

METHODS

In an 8-week pilot randomized clinical trial, 41 participants (M_age = 52.73, SD = 10.91, 56.1% females) with overweight or obesity (M_BMI = 31.86, SD = 4.7) received a CBT for both quitting smoking and weight gain prevention (n = 24) or the same treatment plus CM (n = 17), consisting of providing incentives contingent upon smoking abstinence biochemically verified.

RESULTS

Recruitment success rate was 80.39% (41/51), completion rate was 90.24% (37/41), and mean number of sessions attended (out of 15 possible) was 13.20 (SD = 3.1). Mean satisfaction rating for the treatment (1-10 likert-type scale with 10 being most satisfactory) was 9.73 (SD =.61). Preliminary efficacy data indicated that the CM group achieved higher abstinence rates compared with the CBT condition (100% vs. 58.33%, p = .007). Abstinent participants increased 1.25 kg (SD = 1.79) their baseline body weight at the end of treatment (p = .001).

CONCLUSIONS

Providing weight gain prevention strategies and CM within a smoking cessation treatment seems feasible and acceptable. Preliminary data indicated that including CM facilitates tobacco abstinence rates, nevertheless no advantage for CM was found for weight control.

Effect of smoking cessation on cardiac troponin I concentrations

Chronic elevation of cardiac troponin I (cTnI) is associated with heart failure and cardiovascular death. Paradoxically, observational studies have indicated that current smokers have lower cTnI concentrations than non-smokers. We examined determinants of cTnI in smokers and the effect of smoking cessation on cTnI. Overweight or obese smokers received motivational support and varenicline to aid cessation and dietary advice to limit weight gain. Quitters were defined according to the Russell standard (≤5 cigarettes after the quit date) and validated with expired breath CO <10 ppm. Of the total 122 participants, 108 completed assessments at 12 weeks and 78 were classified as quitters versus 30 who continued smoking. cTnI was measured with a high-sensitivity assay with a limit of detection of 1.2 ng/L (Abbott Diagnostics), and concentrations (log-transformed) were compared between quitters and continuing smokers. cTnI concentrations were significantly higher in men than women and correlated with age, but not with number of cigarettes/day. Quitters had median baseline and 12-week levels of 1.4 ng/L (interquartile range [IQR] 1.2-2.5) and 1.4 ng/L (IQR 1.2-2.4), respectively, while nonquitters had baseline and 12-week levels of 1.5 ng/L (IQR 1.2-2.9) and 1.8 ng/L (IQR 1.3-3.4), respectively. The change in cTnI concentrations from baseline to 12 weeks did not differ between quitters and continuous smokers (p = .7). The results suggest that smoking cessation does not affect levels of cTnI, a marker of chronic subclinical myocardial injury, in contrast to prior observational data suggesting that tobacco smoking is associated with lower cTn concentrations.

Interventions for preventing weight gain after smoking cessation

BACKGROUND

Most people who stop smoking gain weight. This can discourage some people from making a quit attempt and risks offsetting some, but not all, of the health advantages of quitting. Interventions to prevent weight gain could improve health outcomes, but there is a concern that they may undermine quitting.

OBJECTIVES

To systematically review the effects of: (1) interventions targeting post-cessation weight gain on weight change and smoking cessation (referred to as 'Part 1') and (2) interventions designed to aid smoking cessation that plausibly affect post-cessation weight gain (referred to as 'Part 2').

SEARCH METHODS

Part 1 - We searched the Cochrane Tobacco Addiction Group's Specialized Register and CENTRAL; latest search 16 October 2020. Part 2 - We searched included studies in the following 'parent' Cochrane reviews: nicotine replacement therapy (NRT), antidepressants, nicotine receptor partial agonists, e-cigarettes, and exercise interventions for smoking cessation published in Issue 10, 2020 of the Cochrane Library. We updated register searches for the review of nicotine receptor partial agonists.

SELECTION CRITERIA

Part 1 - trials of interventions that targeted post-cessation weight gain and had measured weight at any follow-up point or smoking cessation, or both, six or more months after quit day. Part 2 - trials included in the selected parent Cochrane reviews reporting weight change at any time point.

DATA COLLECTION AND ANALYSIS

Screening and data extraction followed standard Cochrane methods. Change in weight was expressed as difference in weight change from baseline to follow-up between trial arms and was reported only in people abstinent from smoking. Abstinence from smoking was expressed as a risk ratio (RR). Where appropriate, we performed meta-analysis using the inverse variance method for weight, and Mantel-Haenszel method for smoking.

MAIN RESULTS

Part 1: We include 37 completed studies; 21 are new to this update. We judged five studies to be at low risk of bias, 17 to be at unclear risk and the remainder at high risk.  An intermittent very low calorie diet (VLCD) comprising full meal replacement provided free of charge and accompanied by intensive dietitian support significantly reduced weight gain at end of treatment compared with education on how to avoid weight gain (mean difference (MD) -3.70 kg, 95% confidence interval (CI) -4.82 to -2.58; 1 study, 121 participants), but there was no evidence of benefit at 12 months (MD -1.30 kg, 95% CI -3.49 to 0.89; 1 study, 62 participants). The VLCD increased the chances of abstinence at 12 months (RR 1.73, 95% CI 1.10 to 2.73; 1 study, 287 participants). However, a second study  found that no-one completed the VLCD intervention or achieved abstinence. Interventions aimed at increasing acceptance of weight gain reported mixed effects at end of treatment, 6 months and 12 months with confidence intervals including both increases and decreases in weight gain compared with no advice or health education. Due to high heterogeneity, we did not combine the data. These interventions increased quit rates at 6 months (RR 1.42, 95% CI 1.03 to 1.96; 4 studies, 619 participants; I² = 21%), but there was no evidence at 12 months (RR 1.25, 95% CI 0.76 to 2.06; 2 studies, 496 participants; I² = 26%). Some pharmacological interventions tested for limiting post-cessation weight gain (PCWG) reduced weight gain at the end of treatment (dexfenfluramine, phenylpropanolamine, naltrexone). The effects of ephedrine and caffeine combined, lorcaserin, and chromium were too imprecise to give useful estimates of treatment effects. There was very low-certainty evidence that personalized weight management support reduced weight gain at end of treatment (MD -1.11 kg, 95% CI -1.93 to -0.29; 3 studies, 121 participants; I² = 0%), but no evidence in the longer-term 12 months (MD -0.44 kg, 95% CI -2.34 to 1.46; 4 studies, 530 participants; I² = 41%). There was low to very low-certainty evidence that detailed weight management education without personalized assessment, planning and feedback did not reduce weight gain and may have reduced smoking cessation rates (12 months: MD -0.21 kg, 95% CI -2.28 to 1.86; 2 studies, 61 participants; I² = 0%; RR for smoking cessation 0.66, 95% CI 0.48 to 0.90; 2 studies, 522 participants; I² = 0%). Part 2: We include 83 completed studies, 27 of which are new to this update. There was low certainty that exercise interventions led to minimal or no weight reduction compared with standard care at end of treatment (MD -0.25 kg, 95% CI -0.78 to 0.29; 4 studies, 404 participants; I² = 0%). However, weight was reduced at 12 months (MD -2.07 kg, 95% CI -3.78 to -0.36; 3 studies, 182 participants; I² = 0%). Both bupropion and fluoxetine limited weight gain at end of treatment (bupropion MD -1.01 kg, 95% CI -1.35 to -0.67; 10 studies, 1098 participants; I² = 3%); (fluoxetine MD -1.01 kg, 95% CI -1.49 to -0.53; 2 studies, 144 participants; I² = 38%; low- and very low-certainty evidence, respectively). There was no evidence of benefit at 12 months for bupropion, but estimates were imprecise (bupropion MD -0.26 kg, 95% CI -1.31 to 0.78; 7 studies, 471 participants; I² = 0%). No studies of fluoxetine provided data at 12 months. There was moderate-certainty that NRT reduced weight at end of treatment (MD -0.52 kg, 95% CI -0.99 to -0.05; 21 studies, 2784 participants; I² = 81%) and moderate-certainty that the effect may be similar at 12 months (MD -0.37 kg, 95% CI -0.86 to 0.11; 17 studies, 1463 participants; I² = 0%), although the estimates are too imprecise to assess long-term benefit. There was mixed evidence of the effect of varenicline on weight, with high-certainty evidence that weight change was very modestly lower at the end of treatment (MD -0.23 kg, 95% CI -0.53 to 0.06; 14 studies, 2566 participants; I² = 32%); a low-certainty estimate gave an imprecise estimate of higher weight at 12 months (MD 1.05 kg, 95% CI -0.58 to 2.69; 3 studies, 237 participants; I² = 0%).

AUTHORS' CONCLUSIONS

Overall, there is no intervention for which there is moderate certainty of a clinically useful effect on long-term weight gain. There is also no moderate- or high-certainty evidence that interventions designed to limit weight gain reduce the chances of people achieving abstinence from smoking.

No changes in dietary intake after quitting smoking; a prospective study in Switzerland

BACKGROUND

After quitting smoking, quitters frequently increase their weight and change their dietary intake. Still, most studies on the topic are over 20 years old and focused on few dietary markers. We analysed the changes in weight and dietary intake after quitting smoking using a large panel of dietary markers.

METHODS

Prospective study including 5064 participants, 169 of whom (3.3%) quitted during a median follow-up of 5 years. Dietary intake was assessed using a food frequency questionnaire. Participants were excluded if they lacked dietary data or reported extreme total energy intakes (TEI) < 850 or > 4000 kcal/day.

RESULTS

Data from 128 participants (43.8% women, aged 56.0 ± 10.0 years) were used. After quitting smoking, mean weight increased 2.1 ± 0.7 kg; the majority (58%) of the participants gained over 1 kg, and only 7.1% were on a diet to reduce their weight. Total protein intake increased from (median [interquartile range]) 14.4 [12.9-16.4] to 15.1 [13.4-17.9] % of total energy intake (TEI), p = 0.008, while animal protein intake increased from 9.7 [8.0-12.1] to 10.8 [8.5-13.5] %TEI, p = 0.011. Fish intake increased from 27 [17-45] to 37 [19-55] g/day, p = 0.016 and dairy intake decreased from 177 [94-288] to 150 [77-243] g/day, p = 0.009. No other changes were found. Among the 68 (53%) participants who reported time since quitting, quitting for <=1 year led to a decreased consumption of fruits, while the opposite was found for participants who quit for longer than one year. No associations were found between weight or dietary changes and time since quitting.

CONCLUSIONS

People who quit smoking tend to gain weight, do not significantly change their dietary intake, and seem to make little effort to prevent weight gain. Systematic dietary support should be provided to all smokers wishing to quit.

Diet, eating behaviour and weight gain in men and women with overweight/obesity receiving varenicline for smoking cessation

Because trying to quit smoking and not gain weight requires changes in two major behaviours simultaneously we explored eating behaviour in smokers with overweight/obesity making a quit attempt using guideline-based treatment. Participants were randomized to a carbohydrate-reduced or fat-reduced diet. The Three Factor Eating Questionnaire and Binge Eating Scale were completed by 48 of 64 participants in the low-carbohydrate and 47 of 58 in the fat-reduced group at randomization, after 6 and 14 weeks. At 6 weeks, no between group differences were seen in eating behaviour scores thus, we combined the sample for further analyses. In the combined sample, restraint increased (3.94 [95% CI 3.05, 4.83]), disinhibition (uncontrolled eating) decreased (-0.86 [95% CI-1.31, -0.41]) and binge eating decreased (-1.95 [95% CI -2.83, -1.06]), while hunger scores did not change (-0.43 [95% CI -0.89, 0.03]) after 14 weeks. In a general linear model, increase in dietary restraint (P = .012) and decrease in binge eating (P = .040) were associated with lower weight gain (model R² _adj = .147). In a smoking cessation program, dietary support regardless of diet was associated with increased dietary restraint and reduced binge eating. Because smoking cessation causes weight gain these results indicate that dietary support leads to eating behaviour changes that may prevent weight gain.

Smoking cessation improves cardiometabolic risk in overweight and obese subjects treated with varenicline and dietary counseling

BACKGROUND AND AIM

Weight gain after stopping smoking potentially counteracts improvements in cardiometabolic risks. We investigated changes in metabolic syndrome (MetS) components and homeostasis assessment model insulin resistance (HOMA-IR) in smokers given dietary counseling during their quit attempt.

METHODS AND RESULTS

Smokers (≥10 cigarettes/day) with BMI 25-40 kg/m² were randomized to a low-carbohydrate or low-fat diet and treated with a standard course of varenicline for 12 weeks. Quitters were assessed according to the Russell standard (≤5 cigarettes after the quit date) validated with expired breath carbon monoxide (CO) < 10 ppm. Of 122 randomized participants, 108 (89%) completed clinical and laboratory assessments at 12 weeks. As changes in metabolic risk factors did not differ between dietary groups, we combined the groups to compare quitters to continuing smokers. We found similar weight change among 78 validated quitters as 30 continuing smokers (-0.1 ± 3.0 kg vs 0.3 ± 3.1 kg; p = 0.7) and change in waist circumference (-2.0 ± 3.8 cm vs -0.9 ± 3.9 cm; p = 0.2). Changes in triglyceride concentrations (-0.16 ± 0.52 mmol/l vs 0.21 ± 0.95 mmol/l; p = 0.015) and diastolic blood pressure (-0.9 ± 6 mmHg vs 1.9 ± 8 mmHg; p = 0.039) were more favorable in quitters. Changes in other cardiometabolic risks and HOMA-IR did not differ between quitters and continuous smokers, nor did energy intake or resting metabolic rate.

CONCLUSION

Dyslipidemia and blood pressure improved and no early weight gain was seen in quitters, suggesting that dietary intervention can mitigate some of the effects of stopping smoking on cardiometabolic risk factors in overweight and obese smokers.

CLINICAL TRIALS REGISTRATION

NCT01069458.