Zero calorie sweetener could cause weight gain without increasing calories: Animal data

The study, published in Appetite, follows on from previous work which showed that saccharin can induce weight gain when compared with sucrose, despite similar total caloric intake, by evaluating whether such effects are due to the sweet taste of saccharin per se​ or whether the weight gain is associated with insulin-resistance increases in gut peptides such as leptin and PYY in the fasting state.

Led by senior author Dr Marcello Casaccia Bertoluci from the Universidade Federal do Rio Grande do Sul in Brazil, the team reported that Wistar rats receiving saccharin-sweetened supplement along with a free chow diet for 14 weeks increase weight gain in comparison to controls receiving non-sweetened supplement.

“There were no differences in the total caloric or water intake between groups and these findings could be attributed solely to the sweet-taste of saccharin,”​ said the team. “The increase in weight gain, however, was not associated with hyperinsulinemia, increased insulin resistance, fasting leptin or PYY levels in this experimental model.”​

Indeed, Bertoluci and his colleagues concluded that that the sweet-taste of saccharin can promote increases in weight gain without increasing total caloric intake or promoting insulin resistance in Wistar rats – adding that the possibility that saccharin could decrease caloric expenditure or even stimulate glucose transport mediated by gut sweet-receptors should be tested in future studies.

Study details​

The Brazilian research team performed the 14 week experiment in 16 male Wistar rats which received either saccharin-sweetened yogurt or non-sweetened yogurt daily in addition to chow and water ad lib​.

The authors measured daily food intake and weekly weight gain in addition to evaluating fasting leptin, glucose, insulin, PYY and insulin resistance.

“Results showed that saccharin induced greater weight gain when compared with non-sweetened control (p=0.027) despite a similar total caloric intake,” reported Bertoluci and his team. “There were no differences in HOMA-IR, fasting leptin or PYY levels between groups.”

They noted that the greater increase in weight gain in the saccharin group begins in week five, becoming maximal between weeks eight and 12 – with a trend to atenuate the difference along weeks 12 and 14.

Bertoluci and his colleagues concluded that the sweet taste of saccharin can induce mild weight gain in Wistar rats without increasing total caloric intake, and that this weight gain was is not related to insulin-resistance or changes in fasting leptin or PYY.

They added that while the rationale for this increased weight gain is still ‘speculative’, there are a few possible mechanisms, including additional sodium from saccharin leading to greater water retention and weight gain.

“However, this mechanism is unlikely because sodium content was very small as we used diluted saccharin … Moreover we observed that water intake was rigorously similar in both groups,”​ they said.

Further possibilities could be that saccharin led to down-regulation of total caloric expenditure or that the sweet-taste of the non-nutritive sweetener “could stimulate intestinal glucose transport through activation of gut SGLT1 and GLUT2 translocation after activating sweet-taste receptors T1R2 and T1R3.”​

Source: Appetite​
Published online ahead of print, doi: 10.1016/j.appet.2015.11.003​​
“Sweet taste of saccharin induces weight gain without increasing caloric intake, not related to insulin-resistance in Wistar rats”​
Authors: Kelly Carraro Foletto, et al​