It is widely believed by the public that replacing sugars with artificial sweeteners will help reduce calorie (energy) intake and aid weight loss. As a result sales of foods and drinks sweetened with artificially sweeteners are at an all time high, as are rates of overweight and obesity. However, while appropriate use of artificial sweeteners may help control energy intake and bodyweight in the short-term, little is known about the long-term impact of artificial sweetener consumption on energy intake and body weight.

A lower intake of energy relative to energy expenditure promotes weight loss. Therefore, it would make sense that substituting foods and drinks containing artificial sweeteners for those with sugar, weight loss would follow. However, the science is not as straight forward as it may seem: the body is capable of sensing and adapting to a reduced energy intake, and as a result people may compensate for this by eating more later.

Professor David Benton, of the University of Wales, Swansea, conducted a review of the scientific evidence looking at the effect of artificial sweeteners in weight control and energy intake. Publishing his findings in Nutrition Research Reviews*, Professor Benton concluded that at present the scientific evidence suggests there is a lack of convincing evidence to draw firm conclusions on the role of artificial sweeteners on long-term energy intake and bodyweight regulation. Current evidence suggests that, although artificial sweeteners may be helpful in the short-term, there is little long-term benefit of in people of normal, body weight.

Professor Benton suggests this is because ?consumption of artificial sweeteners or low-energy foods tends to be followed by an increase in energy intake to make up for the lost energy in people of a normal bodyweight?. The evidence as its stands, suggests that men, rather than women, and children rather, than adults, are better at compensating. However, people who exercise dietary restraint (i.e. watch what they eat carefully)may benefit from artificial sweeteners as they tend not to compensate for energy intake.

Professor Benton suggests that following a low-fat diet is best for weight loss. ?Energy-dense diets tend to be associated with obesity, and energy-dense foods tend to be high in fat and have a low water content?. High-carbohydrate diets, however, tend to be low in fat. He adds ?a number of studies suggest that the use of artificial sweeteners leads to increased consumption of fat, which in theory could lead to weight gain in unrestrained eaters? as gram for gram fat provides more than twice the calories of sugar. There are a number of reasons why this may be, including that fact that carbohydrates, when consumed as solids, promote satiety (feelings of fullness) more than fat. Therefore, people who eat high fat meals may end up eating more energy than people who eat high carbohydrate meals.

It is clear that artificial sweeteners are not a magic solution to all bodyweight problems but may be helpful to some people as part of an overall diet and lifestyle conducive to slimming or weight control.

Overall, there is a lack of convincing evidence regarding the role of artificial sweeteners in long-term energy intake and body weight regulation for definitive conclusions to be drawn. However, what is clear is that there is a need for a well designed, prospective blinded trial to allow causality to be established.

The body learns how many calories are present in a particular food. If we eat a particular food and the body doesn't get the calorie load it is expecting it will attempt to make up for the shortfall later in the day by producing cues to eat. This mechanism appears to be effective in all but the most restrained of eaters.

Artificially sweeteners are typically between 200 and 2000 times sweeter than sugar (sucrose). For example, aspartame is 200 times sweeter; acesulfame-K is 300 times sweeter, whilst alitame is 2000 times sweeter than sugar.

Data from the National Diet and Nutrition Survey suggests that 42% of men and 32% of women are overweight with a further 25% of men and 20% of women being obese (Ruston et al., 2004).

As sugar is not the primary concern when considering causes of obesity, replacement with artificial sweeteners does not dramatically affect weight control compared with a reduction in fat intake.

Reference URL

Peer reviewed publication and references

Benton D (2005) Can artificial sweeteners help control body weight and prevent obesity? Nutrition Research Reviews 18. 63-76.

Ruston D, Hoare J et al., (2004)The National Diet & Nutrition Survey: adults aged 19 to 64 years. Volume 4. Nutritional status (anthropometry and blood analytes), blood pressure and physical activity. Food Standards Agency. London.

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The Sugar Bureau is the trade association for the UK sugar industry. It is funded principally by British Sugar and Tate and Lyle, with smaller contributions from Irish Sugar and the UK Sugar Merchants Association. Since 1990, The Sugar Bureau has been involved in promoting nutrition research and raising awareness among academics, health professionals, the media and the public about the role of sugars in the diet.

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