A study done by Witte et al. found that older adults who restricted calorie intake showed improvement in short term memory (Witte et al., 2009). The abstract can be found here.
Witte, A. V., Fobker, M., Gellner, R., Knecht, S., & Floel, A. (2009). Caloric restriction improves memory in elderly humans. Proceedings of National Academy of Sciences of the United States of Amercia, 106, 1255-1260.