Past research on the efficacy of low calorie sweeteners (LCS) for weight loss has had mixed results, with some studies showing no effect or weight gain, and some indicating such sweeteners can be helpful. A new study in the American Journal of Clinical Nutrition perhaps can explain these discrepancies.
The authors of the study were Paige E. Miller and Vanessa Perez from the Center for Epidemiology, Biostatistics and Computational Biology, Exponent Inc, in Chicago, IL. (Exponent Inc. is an engineering and scientific consulting company). They performed meta-analyses on two types of research studies. The first was a review of randomized controlled trials (RCTs) in which subjects are randomly assigned to treatment or placebo groups. The second type of research was prospective cohort studies, in which participants are simply followed for a number of years and queried about their consumption of the foods, beverages, or ingredients of interest. The results of RCTs are generally considered to be more reliable than those of other types of studies since differences between groups are typically cancelled out by the random assignments.
Miller and Perez review examined 15 RCTs and 9 prospective cohort studies that investigated the effects of LCSs from foods, beverages or tabletop sweeteners on body weight and body composition. LCS included both non-nutritive sweeteners such as aspartame and sucralose, as well as sweeteners such as sugar alcohols (e.g. xylitol or maltitol) that have fewer calories than the sugar they replace. The RCTs included nearly 2000 subjects, while the prospective cohort studies included almost 104,000 participants.
In their meta-analysis of RCTs, they found that LCS modestly but significantly reduced all outcomes examined, including body weight, BMI, fat mass, and weight circumference. In contrast, in the analysis of prospective cohort studies, the investigators found that LCS intake was significantly associated with a slightly higher BMI.
On the basis of the available scientific literature to date, substituting LCS options for their regular-calorie versions results in a modest weight loss and may be a useful dietary tool to improve compliance with weight=loss or weight-maintenance plans the investigators concluded.
ACSH s Dr. Ruth Kava concurs, These results make complete sense to me it would seem eminently logical that substitution of low calorie sweeteners for full calorie ones would lead to weight loss, assuming of course, that other aspects of diet are held constant. The idea that has recently been widely touted that somehow LCS lead to weight gain via some arcane mechanism should be laid to rest by the results of these meta-analyses. She added, It seems likely that some of the confusion about the effects of LCS on weight result from the fact that cohort studies do not provide the same quality data as do the RCTs. In fact, it is much more likely that confounders were not sufficiently controlled for, leading subjects with higher BMIs who might well have been more likely to use LCSs in attempting to lose excess weight, to be construed to have excess weight because they used LCS but the results of the RCTs indicate that, in fact, the linkage worked in the other direction.