Long term effects of weight loss from a very-low-carbohydrate diet on endothelial function in subjects with abdominal obesity

Objective: To compare the effects of an energy reduced, very low carbohydrate, high saturated fat diet (LC) and an isocaloric conventional high carbohydrate, low fat diet (HC) on lipids and endothelial function after 12-months. Methods: 49 overweight and obese patients (age 50.0+/-7.7 yrs, body mass index 33.7+/-4.1 kg/m2) were randomly assigned to either an energy restricted (∼6-7MJ, 30% energy deficit), isocaloric LC or HC for 52 weeks. Body weight, lipids, flow mediated dilatation (FMD), augmentation index (AIx) and pulse wave velocity (PWV) were assessed pre- and post intervention. Results: Weight loss was similar in both groups (LC -14.9+/-10.5 kg, HC -11.5+/-7.4 kg; P=0.20). There was a significant time x diet effect for FMD (P= 0.045); FMD decreased on the LC diet (5.70+/-3.59% to 3.65+/-2.65%, P=0.001) but remained unchanged on the HC diet (5.86+/-2.54% to 5.51+/-3.52%; P=0.60). PWV improved in both groups but AIx did not change. LDL cholesterol increased by 0.6 mmol/L in the LC group (19%) and did not change in the HC group. Despite a fall of triglyceride in the LC group of 0.58 mmol/L, apoB increased by 3% in the LC group and fell by 6% in the HC group. HDL cholesterol increased by 21% in the LC group and 5% in the HC group. Conclusions: Both diets achieved similar reductions in body weight and improvements in PWV. However LC impaired FMD, suggesting that consumption of LC may have adverse effects on cardiovascular risk via higher LDL cholesterol.