Low carbohydrate and moderately fat-reduced diets similarly affected early weight gain in varenicline-treated overweight or obese smokers.

Introduction: Weight gain is common when stopping smoking. This study compared the effect of advising smokers to follow a diet low in carbohydrates versus a usual fat-reduced diet on weight gain and nicotine withdrawal. Methods: In a randomized clinical trial, 122 men and women smokers with body mass index 25-40 kg/m(2) were assigned low-carbohydrate versus moderately fat-reduced diets. Within a week thereafter all participants started treatment with a 12-week course of varenicline 10 days prior to the target quit date. Brief dietary and motivational counseling was given at all visits. Self-reported abstinence was validated. Results: Protein intake in the low-carbohydrate versus fat-reduced diets was 26.4% of total energy versus 20.0%, fat 38.2% versus 30.1%, and carbohydrates 29.0% versus 41.7% (all P<.001). Mean weight changes for the low-carbohydrate versus fat-reduced groups were -1.2 (SD 2.2) versus -0.5 (SD 2.0) kg, -0.2 (SD 3.3) versus 0.5 (SD 2.6) kg, and 2.2 (SD 4.5) versus 2.1 (SD 3.9) kg at 4, 12, and 24 weeks after the target quit date, respectively (not statistically significant). Smoking abstinence rates did not differ between diets. In the combined groups, point prevalence abstinence rates were 71.0% at 12 weeks and 46.3% at 24 weeks. The Minnesota Nicotine Withdrawal Symptoms score was lower in the fat-reduced group compared with the low-carbohydrate group at weeks 4 and 12. Conclusions: In overweight or obese smokers using varenicline a low-carbohydrate diet was no better than a fat-reduced diet in reducing weight gain but may result in more severe nicotine withdrawal symptoms. Compared to previous studies, cessation rates with varenicline were not impaired by dietary counseling. Implications: The study implies that a popular low-carbohydrate diet does not result in greater weight loss than a moderately fat-reduced diet in overweight and obese smokers who are attempting to quit smoking with the aid of varenicline. Dietary counseling combined with varenicline treatment did not appear to unfavorably influence quit rates compared to previous studies in smokers not selected for overweight or obesity. Notably, the withdrawal symptoms score was lower in the fat-reduced dietary group than the low-carbohydrate group, suggesting a venue for further study.