AURORA, Colo.—Following a low-carb diet can induce weight loss, but it can also significantly raise low-density lipoprotein (LDL) cholesterol and free fatty acids (FFAs), according to a new study from the University of Colorado (Am J Clin Nutr. 2010 Mar;91(3):578-85). Researchers aimed to compare the effect of a low-carbohydrate diet (20 g/d) with a high-carbohydrate diet (55 percent of total energy intake) on fasting and hourly metabolic variables during active weight loss.
Healthy, obese adults (n = 32; 22 women, 10 men) were randomly assigned to receive either a carbohydrate-restricted, high-fat diet; or a calorie-restricted, low-fat diet for six weeks. A 24-hour in-patient feeding study was performed at baseline and after 6 weeks. Glucose, insulin, FFAs and triglycerides were measured hourly during meals. Remnant lipoprotein cholesterol was measured every four hours.
Patients lost a similar amount of weight in both groups; about 13 pounds (P = 0.57). However, iIn the low-carb, LDL levels increased 12 mg per deciliter on average; while the high-carb diet group showed a 7 mg per deciliter decrease. High LDL levels are a risk factor for heart disease because they are linked to clogged arteries.
Additionally, in the low-carb group, 24-hour FFAs (P < 0.0001) increased. FFAs are released into the blood when the body breaks down stored fat. Higher levels make it more difficult for the liver to store glucose, which ups the amount of sugar in the blood.
