November 10, 2015

sweeteners and weight loss

A review of studies which examine low-energy sweeteners and their effect on energy intake and body weight has been published in the International Journal of Obesity, with the authors reporting that use of such sweeteners does not increase energy intake or body weight, and when the sweeteners are used in place of sugar those measurements can be reduced. Roundup comments accompanied this analysis.

Title, Date of Publication & Journal

‘Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including meta-analyses, of the evidence from human and animal studies’

International Journal of Obesity

10 November 2015

Study’s main claims – and are they supported by the data

The paper addresses the question of whether consumption of low energy sweeteners (LES), such as aspartame and saccharin, in place of sugar, leads to reduced intake of calories and a lowering of body weight.  The paper does not address questions about the safety of LESs or whether there is any improvement in health.  It asks whether replacement of sugar by LES in different settings leads to reduced calorie intake and to weight loss.

This is a thorough structured analysis of existing data in both animals and humans. There is no new data. Previous meta-analyses exist of human studies. This paper allows a high level discussion of evidence across both humans and animals addressing the direct biological effects but also the potential impact of switching drinks and food in a real life scenario.

First to investigate is the direct impact on the amount of energy consumed, and secondly we need to know whether this has an impact on weight. The first is easier to demonstrate, especially when other food consumption is controlled. It is evidenced from short term studies. On the other hand, investigating the impact on body weight requires longer term studies, typically lasting several weeks.

Within each scenario, less control allows participants, animal or human, to modify their consumption of other food either to compensate through modified hunger or to respond to change in taste.  Separating animal (mostly rat) studies from human studies, the paper combines information across studies within the classic types of study. For humans these are observational (prospective cohort), short term (<1 day) intervention studies, and sustained (>1 day) intervention studies.

Strengths/Limitations

The paper concludes that: “We found a considerable weight of evidence in favor of consumption of LES in place of sugar as helpful in reducing relative EI and BW, with no evidence from the many acute and sustained intervention studies in humans that LES increase EI. Importantly, the effects of LES-sweetened beverages on BW also appear neutral relative to water, or even beneficial in some contexts.”

This mainly is based on the short term and long term intervention studies.

However within the paper it states that “The results from prospective studies of LES, BW (body weight) and obesity are inconsistent.” These are often very large cohort studies and were all carried out in America. This result, which is not addressed in the papers conclusion, may reflect the difficulty in turning targeted scientific evidence into a wider impact at the population level when there is not the equivalent control of that in a randomized trial (RCT).

Glossary

LES = low energy sweeteners

EI = energy intake

BW = body weight

Any specific expertise relevant to studied paper (beyond statistical)?

This reviewer has very limited knowledge of the food and drinks industry.

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