Based on scientific evidence examined in a new review paper.
- Low calorie sweeteners’ consumption may have to some extent the advantage of satisfying desire for sweetness, according to scientific evidence to date.
- The reduced energy content of low calorie sweetened products is not fully compensated, leading to lower overall caloric intake, based on short-term appetite studies.
- There is no evidence that low calorie sweeteners would disrupt the learned control of energy intake in humans despite claims from individual animal studies.
- Human studies consistently show that the consumption of low calorie sweeteners in place of sugar in the diet can be a helpful strategy as part of a weight loss behavioural programme.
It is really surprising how some nutrition theories tend to be recycled in the media or often be discussed among policy makers without acknowledging the lack of real scientific evidence in their support. This seems to be also the case for claims suggesting that low calorie sweeteners would undermine body weight regulation. Contrary to human studies showing that by reducing the energy density of foods and beverages low calorie sweeteners can be useful in weight management1,2, theories claiming that they would make us crave for more sweetness or that low calorie sweeteners would disrupt body’s energy intake control feed the controversy.
Aiming to provide evidence-based answers to these claims, a new review paper3 by Prof Peter Rogers, University of Bristol, UK, examines the available scientific literature to date on the impact of low calorie sweeteners on weight control and further evaluates three claims regarding the effect of low calorie sweeteners on energy intake and preference for sweetness: 1) the ‘sweet taste confusion’ hypothesis, 2) the ‘sweet tooth’ hypothesis and 3) the ‘conscious overcompensation’ hypothesis. Based on current evidence, the author concludes that there is little or no evidence in support of these claims and explains why these theories don’t stand up to close examination in his review paper entitled ‘The role of low-calorie sweeteners in the prevention and management of overweight and obesity: evidence v. conjecture‘.
The sweet taste confusion hypothesis
First and foremost, it should be clarified that there is no evidence supporting the ‘sweet taste confusion’ hypothesis in humans. According to this theory, tested in animal studies, low calorie sweeteners would impair the body’s learned control of energy intake and weight regulation because there is a mismatch between sweet taste and calorie intake. However, the majority of animal studies do not confirm the theory that low calorie sweeteners would disrupt the sweetness-energy association, a theory generated further to findings of a series of rat studies with saccharin by Swithers et al.4 Indeed, a recent study5 replicating the study design as in Swithers’ experiments concluded: “This result is in opposition to the findings of the Swithers group and others, but is consistent with the majority of animal and human research suggesting the effects of non-nutritive sweeteners are not more harmful than those of caloric sweeteners”.
But why do studies of similar study design find different results? The discrepancy appears to be explained by a crucial difference in procedure. It appears that a crucial piece of evidence used to support the claim that low calorie sweeteners would disrupt the learned control of energy intake in Swithers et al. studies is based on false assumptions confounded by a procedural artefact.
Sweetness without calories and ‘sweet tooth’
The second argument against low calorie sweeteners is rather the most prominent among policy makers claiming that the exposure to sweetness without calories may encourage a sweet tooth and therefore increased intake of sweet, energy-containing foods and beverages. However a large battery of evidence from both short- and longer-term human intervention studies does not support the ‘sweet tooth’ hypothesis6 and rather indicates that the consumption of low calorie sweeteners, studied mostly in the form of beverages, does not increase energy intake and may have to some extent the advantage of satisfying desire for sweetness when consumed shortly before or with a meal.
Can we consciously overcompensate when we choose calorie reduced foods?
Then comes the question about human behaviour and about whether people may consciously overcompensate for ‘calories saved’ when they know they are consuming low calorie sweetened foods or beverages with fewer or no calories. What we know to date from free-living intervention studies is that there is little or no conscious compensation when low calorie sweeteners are substituted for sugar as part of a calorie-counted weight loss diet. On the other hand, when low calorie sweetened foods are used as an excuse for indulgence, e.g. the typical example of choosing a diet soda while eating a whole pizza, full compensation may occur, but yet again no one can predict if the same person would eat one less piece of pizza if a sugar-sweetened soda had instead been chosen. In any case, this certainly has to do with consumer’s nutrition education while the author concludes that, “taken together, there is little evidence for conscious compensation for low calorie sweeteners consumption”.
Facts versus claims: take-away message
Examining what we know to date about sweetness without calories and about the effect of low calorie sweeteners on energy intake and body weight, Prof Peter Rogers concludes in this new literature review that there is little or no evidence in support of claims suggesting that low calorie sweeteners would undermine body weight regulation.
At the very least, the reduced energy content of low calorie sweetened foods and beverages is not fully compensated thus helping us to cut our daily calories down. And of course, reducing calorie intake and managing our overall energy balance (calories in – calories out) are key elements of successful weight loss. This is probably why longer-term intervention studies consistently confirm that the consumption of low calorie sweeteners in place of sugar in the diet can help in modest weight loss. Of course, low calorie sweeteners are not a silver bullet in weight loss and should not be seen like one, but including low calorie sweetened foods and drinks in the diet can be amongst the many strategies used in weight management efforts to help us keep the enjoyment of sweet-tasting foods with fewer or no calories.