Aspartame, saccharin and the alike – which sweetener causes weight gain?

In May 2019, the results of a study on the influence of various sweeteners on the body weight of overweight test persons were published in the American Journal of Clinical Nutrition.

Researchers from Perdue University in the United States studied the effect of different sweeteners on the body weight of 123 adults with a body mass index (BMI) between 25 kg/m2 and 40 kg/m2 over a 12-week period.

The subjects were randomly assigned to one of five groups and were asked to consume between 1.25 and 1.75 litres of a sweetened drink daily during the study period. Depending on the group, it contained aspartame, saccharin, sucralose, rebaudioside from the stevia plant or sugar. While the drink sweetened with sugar contained 400 to 500 kcal, the other sweeteners studied contained less than 5 kcal.

At the beginning of the study, weight, energy intake and consumption, appetite and glucose tolerance were determined. In the course of the study, weight was recorded every two weeks and the other parameters every four weeks. After the twelve-week trial, it was found that the subjects who consumed sugar and saccharin-containing drinks gained an average of 1.85 kg and 1.18 kg respectively. In the aspartame and rebaudioside group, there was no significant change in weight, whereas the subjects who regularly consumed sucralose lost an average of 1.37 kg.

The body composition study showed that the weight change in the sugar group was mainly due to an increase in fat mass and averaged 1.35 kg. In the saccharin group, the weight gain was mainly due to an increase in fat-free mass (+ 0.7 kg). In contrast, subjects who regularly consumed sucralose lost not only weight but also fat mass (-0.3 kg).

The weight changes were related to daily calorie intake and frequency of meals. The calorie intake was shown to increase in the sugar group, but was mainly due to the study related sugar intake. At the same time, however, the subjects ate more frequently during the study period than before. In the sucralose group, the frequency of meals and the daily energy intake decreased. But overall, there was hardly any difference in energy intake between the individual low-calorie sweeteners. The study showed that neither sugar nor sweeteners had an effect on the sugar metabolism during the study period.

The influence of artificial sweeteners on weight has already been investigated many times. Comparisons of different sweeteners show a mixed and sometimes contradictory pattern with regard to weight development. However, the results are mostly limited by short observation periods, small numbers of test persons and other disturbing factors. Even if weight changes could be shown, the underlying mechanisms remain unclear. Currently, effects on the appetite and the feeling of satiety, the energy metabolism and the intestinal microbiome are suspected. The investigation of sweeteners is made more difficult by the fact that they are usually studied in isolation, but are combined in food.

In comparison to sugary foods, the use of artificial sweeteners involves a considerable potential for calorie savings. Thus the presented work shows the great influence of sugary drinks, which often provide large amounts of energy unnoticed and thus contribute to weight gain.

If the long-term effects of low-calorie sweeteners have not yet been sufficiently researched, they can be used in the short term to reduce sugar consumption. In light of the still unclear health effects, they should be consumed in moderation. Whether sugar or sweeteners – as a matter of principle, as few sweetened foods as possible should be used in a healthy diet.