Low-Carb Diets: New Concerns about Cholesterol and Regained Weight

Tomorrow’s Annals of Internal Medicine contains two reports that raise more cautions about low-carbohydrate diets. The first, conducted at Duke University, showed that LDL (“bad”) cholesterol levels rose in 30 percent of low-carbohydrate dieters. The second, conducted at the Philadelphia Veterans Affairs Medical Center, showed that weight lost during low-carbohydrate dieting started to return after six months.

Normally, weight loss causes cholesterol levels to fall. However, some low-carbohydrate dieters have experienced the opposite effect—significant increases of cholesterol levels. In the Duke University study, LDL rose only slightly (and nonsignificantly) for the group overall. However, some participants had marked LDL increases. Two dropped out because of high LDL cholesterol levels: One had an LDL increase from 182 mg/dl to 219 mg/dl in four weeks; the second had an increase from 184 mg/dl to 283 mg/dl in three months. (Normal levels are < 100 mg/dl, and some experts call for lower limits.) A third participant developed chest pain and was subsequently diagnosed with coronary heart disease. In all, 45 people followed the low-carbohydrate diet for 6 months. But 30 percent of them had an LDL cholesterol increase of more than 10 percent.

In the Philadelphia VA study, low-carbohydrate dieters lost substantial amounts of weight over the first six months. But after that point, the average weight began to climb so that weight loss after one year (11.2 pounds) was not significantly better than that seen with comparison diets. Two study participants died, one from hyperosmolar coma five months into the study, and the second from severe ischemic cardiomyopathy ten months into the study.