3.1. Study Population Characteristics
Three hundred and four healthy obese women enrolled in this cross-sectional study. The mean age, height, weight, and BMI of the study participants were 36.49 years (SD=8.38), 161.38 cm (SD=5.90), 80.89 kg (SD=12.45), and 31.04 kg/m2 (SD=4.31), respectively (Table 1). The mean body composition, RMR components, biochemical and anthropometric characteristics of subjects are shown in Table 1.
3.2. Study Participant Characteristics between High and Low Adherence of Low-Carb Diet
All participants were categorized based on the LCDS and divided into two groups (Table 2). The differences between the low and high adherence of the low-carb diet groups were analyzed through independent sample t-test for RMR components, body composition analysis, and biochemical characteristics. As shown in Table 2, participants with high adherence to a low-carb diet had significantly higher LDL-c (P = 0.03). However, subjects with high adherence to a low-carb diet had higher total cholesterol (P = 0.22) and HDL-c (P = 0.10), compared to the low adherence low-carb diet group, but these findings were not statistically significant. There were no significant differences in terms of height, weight, RMR, RMR/kg body weight, normal deviation, Respiratory Quotient, FFM, FBS, and TG between the two groups (P > 0.05) (Table 2).
3.3. Association of Studied Variations and RMR Status
By considering the association of body composition analysis, RMR components and biochemical characters with RMR status, the participants were categorized into 3 groups; Inc. RMR (n=37) (> 5% SD of normal RMR), normal RMR (n=87) (-5% SD<normal RMR<5% SD), and Dec. RMR (n=172) (normal RMR < -5% SD). The differences between the normal, Dec. and Inc. RMR groups were analyzed through one-way ANOVA tests (Table 3). Subjects in Inc. RMR group had significantly higher height (P< 0.006), RMR measurement (P < 0.0001), RMR/kg body weight (P < 0.0001), skeletal muscle mass (P < 0.0001), and soft lean mass (P < 0.0001), compared to the Dec. RMR group. All significant results remained robust after adjusting for age, energy intake, physical activity, and FFM. Furthermore, bodily fat mass (P=0.01) and ISQUICKI (P = 0.02) became significant (Table 3).
3.4. The Association of LCDS and RMR across Deviation of Normal RMR
Multivariate-adjusted models with 95% confidence intervals for the association between LCDS and RMR across DNR are presented in Table 4. In the crude model, no significant association was found between LCDS with Inc. and Dec. RMR (For Inc. RMR: OR: 0.97; 95% CI: 0.93-1.01, P=0.20; for Dec. RMR: OR: 0.98; 95% CI: 0.96-1.01, P=0.31). Furthermore, after adjustment for confounders including age, FFM, physical activity, and energy intake in the final model, the associations remained unchanged. Therefore, no significant association was found between LCDS with Inc. and Dec. RMR (For Inc. RMR: OR: 0.97; 95% CI: 0.92-1.01, P=0.20; For Dec. RMR: OR: 0.97; 95% CI: 0.94-1.00, P=0.14).
The Association of LCDS Components and RMR across Deviation of Normal RMR
The participants’ dietary components of LCDS, based on DNR groups, are shown in Table 5. Differences in some LCDS components between DNRs were non-significant: GL, vegetable protein intake, n3/n6 PUFA, and fiber (gr/1000Kcal) – even after adjustment for the potential confounders. However, the crude differences in carbohydrates (% energy) between the DNRs were not significant (Dec. RMR: OR: 1.11; 95% CI: 0.95-1.30, P=0.15, Inc. RMR: OR: 1.20; 95% CI: 0.95-1.51, P=0.11), but after controlling for confounders like age, FFM, physical activity, and energy intake, the association became marginally significant for Dec. RMR (OR: 0.15; 95% CI: 0.98-1.37, P=0.08). Also, MUFA in the crude model was not significant (Dec. RMR: OR: 0.58; 95% CI: 0.27-1.24, P=0.0.16, Inc. RMR: OR: 0.65; 95% CI: 0.21-0.03, P=0.46), but after controlling for confounders, showed a marginally significant association with Dec. RMR (OR: 0.48; 95% CI: 0.21-1.10, P=0.08). For refined grains, participants with a higher intake were at a 13% lower risk for Inc. RMR (OR: 0.87; 95% CI: 0.77-0.99, P=0.04). However, after adjusting for confounders, the significance disappeared (OR: 0.93; 95% CI: 0.81-1.08, P=0.39).