Low-calorie sweeteners and body weight and composition: a meta-analysis of randomized controlled trials and prospective cohort studies


Background: Replacement of caloric sweeteners with lower- or no-calorie alternatives may facilitate weight loss or weight maintenance by helping to reduce energy intake; however, past research examining low-calorie sweeteners (LCSs) and body weight has produced mixed results.

Objective: The objective was to systematically review and quantitatively evaluate randomized controlled trials (RCTs) and prospective cohort studies, separately, that examined the relation between LCSs and body weight and composition.

Design: A systematic literature search identified 15 RCTs and 9 prospective cohort studies that examined LCSs from foods or beverages or LCSs consumed as tabletop sweeteners. Meta-analyses generated weighted mean differences in body weight and composition values between the LCS and control groups among RCTs and weighted mean correlations for LCS intake and these parameters among prospective cohort studies.

Results: In RCTs, LCSs modestly but significantly reduced all outcomes examined, including body weight (−0.80 kg; 95% CI: −1.17, −0.43), body mass index [BMI (in kg/m2): −0.24; 95% CI: −0.41, −0.07], fat mass (−1.10 kg; 95% CI: −1.77, −0.44), and waist circumference (−0.83 cm; 95% CI: −1.29, −0.37). Among prospective cohort studies, LCS intake was not associated with body weight or fat mass, but was significantly associated with slightly higher BMI (0.03; 95% CI: 0.01, 0.06).

Conclusions: The current meta-analysis provides a rigorous evaluation of the scientific evidence on LCSs and body weight and composition. Findings from observational studies showed no association between LCS intake and body weight or fat mass and a small positive association with BMI; however, data from RCTs, which provide the highest quality of evidence for examining the potentially causal effects of LCS intake, indicate that 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.

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Alex’s Notes: If there is one dieting aid that has controversy surrounding its use, it is artificial sweeteners. From a purely weight-management standpoint, replacing sugar and other caloric sweeteners with lower-calorie or zero-calorie alternatives is bound to help with weight loss, maintenance, or prevention of weight gain. More importantly, they may provide a satisfaction that helps improve adherence to diets. But even this seemingly common-sense use for “non-nutritive” sweeteners has challengers. They claim that use of these products promotes weight gain through altering taste and metabolic signaling, decreasing satiety, increasing appetite, and ultimately increasing food intake. However, not only are these claims decades old and based on observational evidence, but they have also been unsupported by a recent review of randomized clinical trials, and even by a recent randomized clinical trial looking at the effect of low-calorie sweetened beverages on overall dietary patterns.

Like many nutritional beliefs, unfortunately, people still chose to ignore the emerging evidence and hold a blind obedience to their dogmas. But I’m getting ahead of myself. Low-calorie sweeteners (LCS) can be either nonnutritive (zero-calorie) sweeteners or sugar alcohols. The former includes the more controversial Acesulfame potassium, aspartame, and saccharin, but also sucralose, luo han guo, and stevia. The sugar alcohols include Erythritol, xylitol, sorbitol, and a bunch of other “tols”. The purpose of the study at hand was to perform a systemic review and meta-analysis of both randomized controlled trials (RCTs) as well as prospective cohorts (PCs) , separately, to examine the relationship between intake of these sweeteners and body weight, fat mass, BMI, and waist circumference. Importantly, the study populations had to be generally healthy (although being overweight or obese was fine) and the durations had to be greater than two weeks for the controlled trials and greater than six months for the cohorts. 15 trials and 9 cohorts up to September of 2013 fit the bill.

There was a lot of diversity in the studies as well, providing a wide-range of participant “types”. The RCTs comprised 1951 subjects from 4 to 65 years old with a BMI ranging from 22.5 to 37.7 (average was 29), and were anywhere from 3-78(!) weeks in duration. The PCs comprised 103,940 subjects with follow-ups ranging from 1-7.5 years.

And the results only continue to support the use of LCS in place of sugar.

“Findings from the meta-analysis of 15 RCTs—the gold standard study design in medical research—indicate that substituting LCS for sugar modestly reduces body weight, BMI, fat mass, and waist circumference. Although the mean reduction in body weight was modest (0.80-kg decrease), it would not be expected for a single dietary change, ie, replacement of sugar with LCS, to cause clinically meaningful weight loss (53).”

Honestly I couldn’t have said it better myself. As for the PC meta-analysis, it showed a statistically non-significant association between LCS intake and bodyweight and fat mass, but also an extremely minor but statistically significant association with BMI. In other words, LCS intake has no association with bodyweight or fat mass, but there is a trend for those who consume LCS to have a greater BMI by an average of .03. Yeah, I’m not impressed either. Also, are they negligibly larger because they consume LCS, or do they consume LCS because they are negligibly larger? Also, what if the increased BMI is simply a result of more muscle mass? Or perhaps it is from an enlarged liver as an adverse effect of LCS consumption. Who knows? Correlation tells us nothing, but the meta-analysis of the gold-standard in research does. And to answer the first question I posed, it appears that those with greater BMIs must simply consume more LCS rather than vice-versa because the RCTs concluded that LCS can benefit weight and fat loss.

So there you have it, from purely weight-management standpoint, LCS substituted for sugar will benefit you. However, from a safety standpoint on the other parameters of health, more research is definitely needed, especially with the popularity compounds like stevia are garnering.

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