This article in the New York Times suggests some of the problems that sugar substitutes may provoke.
It is an interesting read but the concluding commentary is the crux of the issue:
Dr. Robert Lustig, an obesity expert and professor emeritus at the University of California, San Francisco, said that artificial sweeteners confuse the body: their sweet flavors send a signal to the brain and the digestive system to brace for a flood of sugar. But when those calories never arrive, it can send hormones like insulin out of whack, over time leading to metabolic dysfunction, he said.
…..Dr. Pepino [assistant professor in the department of food science and human nutrition at the University of Illinois at Urbana-Champaign] explained that for thousands of years humans lived in a world where intensely sweet flavours were rare, and that they became a cue to the body to regulate blood sugar levels. She advises people to consider sweetness, in whatever form, as a treat. “Sweetness should be consumed in moderation, regardless of whether it has calories or not,” she said.
I feel confirmed in my view that the British government sugar tax was a nice headline and did help to remove a lot of sugar from soft drinks, even though confectionary was conspicuously omitted, but in fact sugar was removed only to be substituted by a range of replacement sweeteners all of which are effectively untested. They are in fact being tested on us all -now.
I cannot imagine significant health improvement will result until we tax, not sugar, but sweetness.