Impact of baseline dietary quality on the efficacy of a dietitian-guided weight reduction program.

Aim: This pre-post intervention study aimed to assess the relationship between baseline dietary quality and the efficacy of a dietitian-guided weight reduction program, which has not been thoroughly documented to date.

Methods: Ninety-two consecutive obese or overweight patients visiting a tertiary center clinic for weight reduction were enrolled in this study. Participants received a dietitian-guided weight reduction education program aimed at reducing daily caloric intake by 500 kcal and improving adherence to the Mediterranean diet for 3 months. Baseline dietary quality was assessed using the 14-item Taiwanese Mediterranean Diet Adherence Screener (T-MEDAS), where a higher T-MEDAS score reflects greater adherence to the Mediterranean diet. Additional covariates, including dietary behaviors, lifestyle factors, and comorbidities were also recorded. The primary outcome was the percentage of weight reduction at 3 months, analyzed using restricted cubic spline models and generalized estimating equations (GEE) to account for the correlation between weight change and the baseline T-MEDAS scores.

Results: Thirty-nine participants were excluded due to major illnesses, use of anti-obesity medications, or loss to follow-up. Among the remaining 53 participants (mean age 41.2 ± 12.8 years, 56.6% female), the average weight reduction was 3.9 ± 3.3% from a baseline weight of 98.5 ± 12.8 kg. Participants who did not achieve a weight reduction of more than 5% had higher baseline T-MEDAS scores compared to those who did (5.4 ± 1.7 vs. 4.1 ± 1.8, p = 0.026). A restricted cubic spline model, adjusted for covariates including age, gender, diabetes mellitus (DM), dyslipidemia, and smoking, revealed a significant inverse relationship between higher baseline T-MEDAS scores and weight loss. After controlling for various confounders, GEE analysis demonstrated that higher baseline T-MEDAS scores were significantly associated with less weight loss (beta: -4.1, 95% CI: -5.6 to -2.6, p < 0.001).

Conclusions: Higher baseline dietary quality was associated with reduced effectiveness of a dietitian-guided weight reduction program. This suggests that additional strategies may be required to improve the success of weight loss interventions in individuals with higher baseline dietary quality.