Abstract 3597: Failure of Suppression of Circulating Free Fatty Acids is Associated with Increased Low-Density Lipoprotein Cholesterol in Response to Weight Loss
Introduction: Low carbohydrate (LCARB) diets are a popular method for weight loss. It is unclear how these diets affect metabolic and lipid profiles during active weight loss.
Methods: 35 patients were randomized to either an isocaloric LCARB (Atkins®) or a low calorie, low fat (LCAL; LEARN) diet for 6 weeks. Caloric intake was based on fat-free body weight and 24-hr energy intake. Subjects underwent 24-hr feeding studies, consisting of 3 daily meals, at baseline (50% CHO, 35% fat, 15% protein) and at 6 weeks (randomized diet). For these studies, hourly triglycerides (TGs), FFAs, insulin, and glucose were measured along with remnant lipoprotein cholesterol (RLP-c) at six different time-points. Fasting lipids were measured at 2-week intervals.
Results: At 6 weeks, weight loss was not different by diet (LCARB, − 12.9 ±7.3; LCAL, − 14.5 ±11.0 lbs, mean +/− SD). Both LCARB and LCAL diets had significantly reduced fasting TGs and fasting RLP-C compared to baseline. However, in only the LCARB diet, there was a reduction in fasting insulin and an increase in fasting FFAs (159 ± 290 uEq/L, p=0.04). Relative to the LCAL diet, fasting LDL cholesterol (LDL-C) was increased in the LCARB diet (ΔLCARB-ΔLCAL, 18.0 ± 6.2, p=0.01). During the feeding studies, both groups had a significant reduction in 24-hr insulin and RLP-C but 24-hr TGs remained unchanged. As expected, 24-hr FFAs were suppressed during meal intake in the LCAL group. However, the LCARB group demonstrated a two-fold increase in 24-hr FFAs (AUC; 9686 ± 1801 vs. 4798 ± 1373, p<0.01). At 6 weeks, differences in fasting LDL-C for both groups significantly correlated with increases in fasting (r=0.41, p=0.02) and 24-hr FFAs (r=0.52, p<0.01).
Summary and Conclusion: Despite similar weight loss in the LCARB and LCAL diet groups, fasting and 24-hr FFAs failed to be suppressed in the LCARB diet. The positive association of FFAs with fasting LDL-C suggests that a LCARB diet may have an adverse effect on overall cardiovascular risk.