There is an ongoing debate about the possible influences of nonnutritive sweeteners (NNS) on body weight. We conducted a systematic review and meta?analysis of randomized controlled trials (RCTs) with NNS to assess their impact on body weight. We systematically searched for RCTs at least 4 weeks in duration, evaluating the effect of NNS on body weight, both in subjects with healthy weight and in subjects with overweight/obesity at any age, and compared the effects of NNS vs caloric and noncaloric comparators. The primary outcome was the difference in body weight between NNS and comparators. Twenty studies were eligible (n = 2914). Participants consuming NNS showed significant weight/BMI differences favouring NNS compared with nonusers. Grouping by nature of comparator revealed that NNS vs placebo/no intervention and NNS vs water produced no effect. When comparing NNS vs sucrose, significant weight/BMI differences appeared favouring NNS. Consumption of NNS led to significantly negative weight/BMI differences in unrestricted energy diets, but not in weight?reduction diets. Participants with overweight/obesity and adults showed significant favourable weight/BMI differences with NNS. Data suggest that replacing sugar with NNS leads to weight reduction, particularly in participants with overweight/obesity under an unrestricted diet, information that could be utilized for evidence?based public policy decisions.
The present systematic review and meta-analysis of 20 randomised controlled trials (n = 2914) found that the use of low/no calorie sweeteners results in clinically appreciable lower body weight/ body mass index (BMI) values in certain clinical scenarios. The effect is more evident when low/no calorie sweeteners are used as a substitute for sugar, especially in adults, in people with overweight/obesity, and in those following an unrestricted diet.
These data confirm the presumption that, when used to replace caloric sweeteners such as sugar, low/no calorie sweeteners have a beneficial effect on body weight, while when compared to noncaloric comparators, they do not promote significant variations in body weight. Comparing their findings with previously published research, the authors note that their results are in line with most published meta-analysis of RCTs, while contradictory results between meta-analyses of observational studies and of RCTs have been described in the literature. However, the study highlights limitations of observational evidence for diet-disease relations, including imprecise exposure quantification, collinearity among dietary exposures, displacement/substitution effects, healthy/unhealthy consumer bias, residual confounding, and effect modification. This reinforces the importance of evidence hierarchy evaluation, particularly when considering meta-analyses as policy-making instruments, which requires a summary of the best-quality available evidence.
In all, the present meta-analysis found no evidence suggesting that low/no calorie sweeteners’ consumption promotes body weight gain. Rather, these data indicate that replacing sugar with low/no calorie sweeteners leads to weight reduction, an effect that is particularly evident in adults, people with overweight/obesity, and those under an unrestricted, ad-libitum diet. The authors conclude that this information will be beneficial to clinicians making dietary recommendations for weight loss and can be used to provide a strong basis for evidence-based public policy decisions.