Reply to CM Strik and CJ Henry

Department of Nutrition
Centre for Advanced Food Studies
The Royal Veterinary and Agricultural University
30 Rolighedsvej
DK-1958 Frederiksberg
Denmark
E-mail: bsl{at}kvl.dk
Department of Applied Nutrition & Food Chemistry
Lund University
Sweden

Dear Sir:

We fully agree that our study should not discourage others from researching the potential role of low-glycemic-index diets in managing obesity and modifying the risk factors for type 2 diabetes and coronary heart disease. For this reason we concluded in our article that "Further long-term studies, preferentially 6–12 mo, are needed to substantiate these findings" (1).

As stated in our discussion, we also agree that a longer study period or the inclusion of more subjects might have shown a significant difference in body weight. Although there was a trend toward a difference in energy intake between the groups (P = 0.09), we believe that our finding of no significant difference in body weight loss (P = 0.31) or fat loss (P = 0.20) after 10 wk between the diet groups (n = 22–23 subjects per group) seriously questions the clinical relevance of glycemic index in body weight control.

The concerns raised by Strik and Henry with regard to the ad libitum design of the study are interesting. It is not unusual for overweight subjects to complain about the quantity of food when they are served low-fat, high-carbohydrate, fiber-rich diets, because these diets are probably more bulky and satiating than are the subjects' habitual diets (2). However, the dietary record data from weeks 5 and 10 clearly confirmed what we actually intended, namely that the test foods provided were only part of the subjects' diet. We strongly believe that >50% of the energy consumed voluntarily should leave room for changes in energy intake and body weight. Also, the design mimics the current dietary guidelines, which recommend the consumption of 50–55% of energy as carbohydrate.

ACKNOWLEDGMENTS

None of the authors had a conflict of interest.

REFERENCES

1. Sloth B, Krog-Mikkelsen I, Flint A, et al. No difference in body weight decrease between a low-glycemic-index and a high-glycemic-index diet but reduced LDL cholesterol after 10-wk ad libitum intake of the low-glycemic-index diet. Am J Clin Nutr 2004;80:337–47.
2. Raben A, Jensen ND, Marckmann P, Sandstrom B, Astrup A. Spontaneous weight loss during 11 weeks' ad libitum intake of a low fat/high fiber diet in young, normal weight subjects. Int J Obes Relat Metab Disord 1995;19:916–23.