Author(s): MOITZI, A., ROGI, B., KRUPICKA, R., FEICHTER, A., KOENIG, D., Institution: UNIVERSITY OF VIENNA, Country: AUSTRIA, Abstract-ID: 630

INTRODUCTION:
An increasing number of recreational active athletes are considering a low-carbohydrate, high-fat (LCHF) diet for health and performance reasons. Nevertheless, the question remains whether an LCHF diet can be considered healthy, especially for individuals at higher risk for cardiovascular diseases. Therefore, the objective was to investigate the impact of a LCHF diet on blood lipid profiles in endurance trained individuals, comparing it to a high carbohydrate (CHO) diet with varying glycaemic indices.
METHODS:
In a randomised, parallel group design, recreationally active runners (n=65, VO2 peak=55±8 mL·min-1·kg-1) completed 10 weeks of an ad libitum dietary intervention (LOW-GI:≥65% low GI CHO per day, n=24; HIGH-GI:≥65% high GI CHO per day, n=20; LCHF:≤50g CHO daily, n=21) together with prescribed five sessions of an endurance training program. Dietary recalls were conducted twice a week during the intervention phase. Serum was collected at the beginning and after 10 weeks and was analysed for fasting total cholesterol (TC), triglycerides (TG), LDL-C and HDL-C. Data were analysed using a 2-way mixed ANOVA und are presented as mean±STD.
RESULTS:
Significant time x group interactions were found for TC, HDL-C and LDL-C and are presented in the following. After the intervention, TC was significantly higher in LCHF (196±37 mg·dL-1) compared to LOW-GI (171±41 mg·dL-1) or HIGH-GI (152±28 mg·dL-1, p<0.001, ηp2=0.201). LDL-C was reduced in LOW-GI (-14±20 mg·dL-1) and HIGH-GI (-13±18 mg·dL-1), increased for subjects in LCHF (17±21 mg·dL-1, p<0.05 respectively) and differed significantly between all groups after 10 weeks (p<0.001, ηp2=0.257). Participants in HIGH-GI experienced a reduction in HDL-C (-3±9 mg·dL-1, p=0.006), while the changes in the other two regimes were not significant. Additionally, during the intervention, intake in saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) was significantly higher in LCHF compared to CHO groups (p<0.001, ηp2 = 0.459, ηp2 = 0.520). Compared to LOW-GI intake in SFA (27±13 vs. 60±20 g·day-1) and MUFA (28±11 vs. 63±23 g·day-1) was around 45% higher in LCHF. Intake in soluble and insoluble fibre differed significantly between groups (p<0.001, ηp2 = 0.507, ηp2 = 0.378) with the highest intake in LOW-GI (12±3 and 28±6 g·day-1) and the lowest intake in LCHF (6±2 and 18ׅ±8 g·day-1).
CONCLUSION:
Although a LCHF diet is often recommended for weight loss and improvement of fat oxidation, the current data suggest that a LCHF diet, even if together with regular endurance exercise, significantly impairs blood lipids compared to a high CHO diet. In addition, a higher fibre intake combined with a lower intake of SFA, resulted in favourable changes in blood lipids during a CHO rich diet, independent of GI. These findings suggest that active individuals should consider the potential effects of their diet on blood lipid levels, as a LCHF diet may counteract the benefits of exercise thereby potentially increasing their atherogenic risk profile.