Switching 24 months old mice fed ad libitum to CR for one month does not significantly change BW, SUM J , and intestinal mass. Interestingly, they found no changes in mRNA levels of sugar transporters associated with changes in SUM J . As in the previous study, they found no changes in mRNA levels of fructose transporters associated with changes in SUM J .
Caloric restriction seems to be associated with marked increases in intestinal absorptive capacity.
This adaptive increase is developed over a long period of time and can be reversed by ad libitum feeding of a much shorter duration. However, changes in levels of transporter mRNA and in intestinal mass are not detected.