The actual study has to be paid for.
Cornell was one of the authors and from their news article:
"The study shows a novel metabolic pathway for dietary glucose with erythritol, an unrecognized product of glucose metabolism. Results found that erythritol is not only absorbed from food but is also produced by the body. By substituting carbon atoms in glucose with “heavy” carbon (13C), the researchers followed the route of glucose throughout metabolism in the body."
So both consumed and produced by body...
"“This result proves that the body can synthesize the sugar alcohol itself,” said Hiller. “Erythritol is not consumed and released from the body unchanged; it has an impact on the metabolism of our body. This finding is in contrast to all previous assumptions.”
According to Cassano, “With the finding of a previously unrecognized metabolism of glucose to erythritol and given the erythritol-weight gain association, further research is needed to understand whether and how this pathway contributes to weight-gain risk.”"
They don't understand the details of the weight gain mechanism but the study indicates a connection.
Again the learning thing for me in glycemic index is not everything! A weight gain response (insulin?) can be provoked w/o a BS rise. It's just something to be noted. IMO