Previous meta-analyses of intervention studies have come to different conclusions about effects of consumption of low-calorie sweeteners (LCS) on body weight. The present review included 60 articles reporting 88 parallel-groups and cross-over studies ≥1 week in duration that reported either body weight (BW), BMI and/or energy intake (EI) outcomes. Studies were analysed according to whether they compared (1) LCS with sugar, (2) LCS with water or nothing, or (3) LCS capsules with placebo capsules. Results showed an effect in favour of LCS vs sugar for BW (29 parallel-groups studies, 2267 participants: BW change, −1.06 kg, 95% CI −1.50 to −0.62, I2 = 51%), BMI and EI. Effect on BW change increased with ‘dose’ of sugar replaced by LCS, whereas there were no differences in study outcome as a function of duration of the intervention or participant blinding. Overall, results showed no difference in effects of LCS vs water/nothing for BW (11 parallel-groups studies, 1068 participants: BW change, 0.10 kg, 95% CI −0.87 to 1.07, I2 = 82%), BMI and EI; and inconsistent effects for LCS consumed in capsules (BW change: −0.28 kg, 95% CI −0.80 to 0.25, I2 = 0%; BMI change: 0.20 kg/m2, 95% CI 0.04 to 0.36, I2 = 0%). Occurrence of adverse events was not affected by the consumption of LCS. The studies available did not permit robust analysis of effects by LCS type. In summary, outcomes were not clearly affected when the treatments differed in sweetness, nor when LCS were consumed in capsules without tasting; however, when treatments differed in energy value (LCS vs sugar), there were consistent effects in favour of LCS. The evidence from human intervention studies supports the use of LCS in weight management, constrained primarily by the amount of added sugar that LCS can displace in the diet.
The main conclusion of the present systematic review and meta-analysis was that the consumption of low/no calorie sweeteners vs sugar decreases body weight via decreasing daily energy intake. It was also found that the greater the amount of displacement of added sugars in the diet, the bigger the beneficial effect from low/no calorie sweeteners use.
The importance of this new review and meta-analyses is that it provides answers to three key questions about the potential effects of low/no calorie sweeteners on body weight, Body Mass Index (BMI) and energy intake: (1) the effects of low/no calorie sweeteners compared with sugar (i.e., when there is a difference in energy content of the target beverages and/or foods consumed, while taste is controlled); (2) the effects of low/no calorie sweeteners compared with water or nothing (i.e., where there is no meaningful difference in energy content between treatments, while there is a difference in taste); and (3) the effects of low/no calorie sweeteners consumed in capsules vs placebo capsules (i.e., where there is no meaningful difference in energy content between treatments, and no difference in taste).
For low/no calorie sweeteners vs sugar, the results from both parallel-groups and cross-over randomised controlled trials showed that body weight, BMI and energy intake were reduced by consumption of low/no calorie sweeteners compared with sugar, which is consistent with the primary intended use of sugar alternatives.
In studies comparing low/no calorie sweeteners vs water/nothing, differences were observed among studies, but overall no effect on body weight or BMI was found. This is reflective of the fact that there is zero difference in caloric content of the low/no calorie sweeteners and water/nothing in these studies. Also, this outcome indicates a lack of effect of dietary exposure to sweetness on intake of sweet foods and beverages. Similarly, for low/no calorie sweeteners vs placebo, the results of the meta-analysis showed no effect on weight outcomes of low/no calorie sweeteners consumed in capsules compared to the consumption of placebo capsules.
Based on these findings, the authors of this study conclude that: “The evidence from human intervention studies supports the use of LCS [low-calorie sweeteners] in weight management, constrained primarily by the amount of added sugar that LCS can displace in the diet.”