Dieting affect the brain

How does dieting affect the brain? This question was addressed by researchers in Australia. The experiment used 40 middle-age women in Adelaide, Australia; half were on a diet and half were not (National Post, December 1, 2003). The mental arithmetic part of the experiment required the participants to add two three-digit numbers. The amount of time taken to solve the 48 problems was recorded. The participants were given another test that required them to repeat a string of five letters they had been told 10 seconds earlier. They were asked to repeat the test with five words told to them 10 seconds earlier. The data were recorded in the following way:

Column 1: Identification number
Column 2: 1 = dieting, 2 = not dieting
Column 3: Time to solve 48 problems (seconds)
Column 4: Repeat string of 5 letters (1 = no. 2 = yes)
Column 5: Repeat string of 5 words (1 = no, 2 = yes)

Is there sufficient evidence to infer that dieting adversely affects the brain?