Sugar substitutes can promote glucose intolerance, imbalance gut flora

From The Scientist:

Non-caloric sweeteners can spur glucose intolerance in mice and some people, according to a study published today (September 17) in Nature. Researchers from the Weizmann Institute of Science in Israel and their colleagues have uncovered “the unexpected effect that artificial sweeteners drive changes in the [gut] microbiota, which promote glucose intolerance,” said University of Chicago pathologist Cathryn Nagler, who studies how the microbiota regulate allergic responses to food and penned an editorial accompanying the study.

From the USDA via a 2014 Colorado State University study:

Obesity rates among children in the United States have tripled in the past three decades and approximately one third of all children or adolescents are currently overweight or obese (CDC). Obese children are more likely to be pre-diabetics and have one or more risk factors associated with cardiovascular disease, problems that become exacerbated as they enter adulthood. To combat weight gain and obesity related disease a number of low energy foods, usually containing non-nutritive sweeteners (NNS) such as saccharine, sucralose, and aspartame have become increasingly prevalent and are recommended sugar substitutes for individuals with Type 2 diabetes. However, two recent human observational studies found positive correlations between consumption of artificial sweeteners, particularly diet sodas, with increased obesity and metabolic syndrome.Weight gain is thought to occur when energy intake surpasses energy expenditure; and foods sweetened with NNS's are designed to reduce caloric consumption while enhancing the flavor of many foods. However, new insights into the role of intestinal flora in harvesting energy from the diet and in contributing to both increased appetite and insulin resistance suggest that the "energy in/energy out" equation may be oversimplified. In particular, several studies support that the relative proportion of the two major intestinal bacterial phyla, Firmicutes and Bacteriodetes, affect the harvest of calories from the diet. Therefore, if NNS alter the intestinal flora such that there are proportionately higher levels of Firmicutes, foods that would normally have passed undigested from the body are metabolized and absorbed through the intestines, increasing the total calories available to the host. We hypothesize that consumption of NNS may later the intestinal microflora to favor greater dietary energy harvest and/or increased inflammation associated with obesity and this study is designed to explore this hypothesis.  

Be careful of artificial sweeteners. Try stevia instead. The Japanese have been using it since the 1970s and the Guarani indians from South America used it long before that.