Effects on body weight and composition
IS are commonly used by consumers as sugar substitutes
as part of weight-loss diets or to control energy intake
and prevent weight gain.
Data in adults
Two meta-analysis (Table 2) [9, 16], a systematic review
[17] and several original articles [18–29]examined the
relationship between IS consumption and changes in
body composition and weight. A meta-analysis [30] took
into account observational studies (with nine articles included)
and randomised controlled trials (RCTs, with 15
articles included) in adults and children. The section on
observational studies showed no relationship between IS
consumption and changes in body weight or fat mass
but showed a slight increase in BMI (+0.03 kg/m2 on
average). The section on RCTs showed that replacing
sugars with IS in sweet products resulted in moderate
weight loss (with an estimated average effect of 0.8 kg)
and a decrease in BMI (-0.24 kg/m2 on average) for time
periods ranging from three weeks to 18 months. This
meta-analysis, of good methodological quality, highlights
the extreme variability of results from studies with a
similar design (whether RCT or observational) and the
differences in results between observational studies and
RCTs. In the meta-analysis by De la Hunty [9], eight
studies on very heterogeneous populations (people with
energy restrictions and unrestricted diets, normal-weight
and obese people, in normal living conditions and in
metabolic chambers) were included. According to the
authors, the effect of IS on weight loss is significant.
They extrapolate the theoretical reduction of 220 kcal/
day related to the replacement of sugars with aspartame
over the long term, and by postulating its maintenance
over time, calculate that this reduction could result in
weight loss of 0.2 kg per week. However, the methodological
weaknesses of this meta-analysis has to be
emphasised, particularly the lack of essential information
related to the study selection process and the statistics
applied to assess heterogeneity. The systematic review
by Wiebe et al. (2011) cites two intervention studies
comparing the effects of artificially sweetened drinks
and sugar-sweetened drinks on BMI [31,32]. These studies,
focusing on different populations (normal-weight
women in one and overweight women in the other), had
different results (no effect in normal-weight women, reduced
weight in overweight women). Five other randomised
controlled trials [21, 24, 25, 27, 29] were
identified. They were all undertaken in overweight subjects
and the majority focused on very small populations
(between 20 and 50 subjects). Two demonstrated modest
weight loss of 1.2 and 1.5 kg on average, but the
other three, including the one with the largest study
population (n = 318), did not show any effects on weight
loss related to the consumption of artificially sweetened
beverages compared to the consumption of sugarsweetened
beverages or water. There are also seven prospective
observational epidemiological studies with
highly heterogeneous results. One study did not show
any association between IS consumption and changes in
body composition [23]; four studies reported a positive
association, i.e. a significantly higher body weight or
waist size in IS consumers [18–20,28]; and two studies
reported a negative association [22, 26].
In conclusion, observational and intervention studies report
contradictory associations between IS consumption and weight loss. Therefore, no conclusion can be drawn as
to the long-term effect of replacing caloric sweeteners
with IS on the weight of regular adult consumers of sweet
products.

Data in children
Four RCT studies focusing on the relationship between
IS consumption and body composition were identified.
In three of these studies, changes in weight and BMI did
not differ between IS consumers and non-consumers
[33–35]. These studies focused on overweight or obese
children and had methodological limitations. The fourth
study, of good methodological quality, examined the
effects of consuming 250 mL/day of an artificially sweetened
drink, compared to the same amount of sugarsweetened
drink, in 641 normal-weight children (aged
four to 12 years), who were regular consumers of sugarsweetened
drinks, for 18 months [36]. This study showed
a significant decrease in the BMI z-score (the most relevant
criterion to assess changes in corpulence in growing
children) in the group that consumed artificially sweetened
drinks. The change in body weight between the two
groups differed by 1 kg on average. Of the seven prospective
epidemiological studies in children, five [37, 38] observed
a positive relationship between IS consumption
(primarily in beverage form) and weight over time, while
two [37] did not find any relationship. To explain these
findings, the authors of these studies assumed that subjects
‘at risk for weight gain’ or with less healthy food profiles
were those who consumed the most IS in order to
reduce their energy intake.
Most of the prospective observational studies undertaken
in children show that IS use is paradoxically associated
with weight gain, although the causality of this
relationship has not been established. The four available
controlled trials showed conflicting results but none reported
weight gain. No conclusions can be drawn from
all of these studies as to the significance of IS for weight
management in children and adolescents.