McMillan-Price and colleagues1 are to be congratulated for performing a large study to examine the impact of low-glycemic-load weight loss diets. However, the conclusions do not tally with the data in the article. All diets caused fat loss, and there was no significant difference between them. The post hoc analysis of weight loss in women is not justified without first showing a significant interaction between sex and fat loss. Although the high-carbohydrate, low–glycemic index (GI) diet lowered low-density lipoprotein cholesterol (LDL-C) levels the most, the high-protein, low-GI diet lowered the high-density lipoprotein cholesterol (HDL-C) ratio the most. Thus, the conclusion that the high-carbohydrate, low-GI diet is best for lowering heart disease risk is not justified on the data presented. The results of the study in relation to LDL-C are very unusual, since striking reductions in saturated fat were reported with all the diets but elevations in LDL-C levels were observed in 2 of the diets. The fact that HDL-C level rose despite the reported reductions in total dietary fat in all the diets casts doubt on the food records. The low level of energy reported in the food records does not accord with the relatively low amount of weight lost. Perhaps the diets are best described as recommended patterns rather than controlled diets.
Clifton P. Glycemic Load and Cardiovascular Risk. Arch Intern Med. 2007;167(2):206. doi:10.1001/archinte.167.2.206-a