November 10, 2015

expert reaction to meta-analysis of low-energy sweeteners, energy intake and body weight

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. A Before the Headlines analysis accompanied these comments.

Prof. Stephen O’Rahilly, Professor of Clinical Biochemistry and Medicine, and Director of the Metabolic Research Laboratories, University of Cambridge, said:

“Getting clear answers to questions about the relationship of specific dietary constituents and human health are frequently confounded not only by the technical challenges of obtaining accurate data regarding human food intake but also by the deeply held beliefs of  influential commentators. This paper is refreshing in its attempt to address the entire body of published literature concerning the link between the consumption of artificial sweeteners and obesity risk in as objective and unprejudiced manner as is currently possible. The authors’ conclusion that the habitual intake of fluids sweetened by calorie-free agents, when compared to the ingestion of beverages sweetened by sugars, is associated with a trend toward lower, and not higher, risk of obesity is compelling. It is reassuring that not only do these artificially sweetened beverages seem less predisposing to obesity than sugar sweetened drinks, they appear to be at least equivalent and even possibly superior to the ingestion of water. Importantly, the commonly asserted idea that drinks that taste sweet but do not contain calories might promote obesity is not supported by this objective analysis of the existing body of data.”

Ms Catherine Collins, Principal Dietitian at St George’s Hospital NHS Trust, said:

“‘Is there any point in choosing low calorie drinks?‘ is a common question from people trying to lose weight. There’s been plenty of uninformed media comment in the past year suggesting little benefit in swapping sugary, calorie-laden drinks for low calorie versions in the battle for weight loss, with some research suggesting that sweeteners may encourage weight gain.

“So this review of the evidence on low calorie sweeteners is welcome. The authors state there’s an awful lot of animal studies out there that bear little relation to how we use sweeteners in our diet. Most of these mice and rat studies also tinkered with diet as well as the sugar/sweetener consumption, or gave the animals sweeteners at levels equivalent to us downing a few hundred sweetener tablets each day. It’s also difficult to separate out whether drinks with sweetener helped weight loss as dietary approaches used in different trials varied so much.

“However, the authors conclude from existing human research that choosing low calorie artificially-sweetened foods and drinks over full-sugar varieties consistently reduces calorie intake – and contributes to ongoing weight loss in both children and adults. This isn’t surprising given that a 500ml bottle of cola provides over 200 kcals a serving – but a similar sized bottle of diet cola less than 2 kcals. Of course the success of using low calorie sweeteners to help weight loss is related to overall daily calorie intake from proteins, fats, carbohydrates and alcohol in the diet. The authors show that on average, people ‘saved’ between 75 to 514 kcals per day in substituting low calorie sweeteners in place of sugar in foods and drinks.

“Finally, the authors demolish the nutri-myth that low calorie sweeteners encourage a higher sweet food intake (and hence more calories, and so more weight gain). In fact, the opposite is true. Low calorie sweeteners will help you control your weight, and not make you gain weight. Oh, and they contribute to protecting your teeth as well.”

‘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’ by P J Rogers et al. is published in the International Journal of Obesity.  

Declared interests

Prof. Stephen O’Rahilly: “Acting as an agent of Cambridge Enterprise, the arm of the University of Cambridge that interacts with industry, I am reimbursed for the provision of independent scientific advice on drug development in metabolic diseases to AstraZeneca, Medimmune and Pfizer. I have no significant interactions or collaborations with the food industry. I have, in the past, had preliminary discussion with Unilever that did not lead to any significant collaborative work and I have lectured at scientific meetings sponsored by Nestle.”

Ms Catherine Collins declares that she has no relevant interests.