Research into the benefits of children eating breakfast has previously focused on educational and cognitive performance as well as behavior. Few nutritional investigations have utilized brain imaging technology in order to examine how breakfast influences brain function. This single case study used quantitative electroencephalography (qEEG) in order to assess how three different breakfast choices affected a 12-year-old female’s brainwave activity. The three different breakfast conditions included no breakfast, a high-sugar/high- carbohydrate breakfast, and a nutritionally balanced breakfast. The findings indicated that skipping breakfast significantly increased high beta activity associated with anxiety and focus issues. Eating a high-sugar/high- carbohydrate breakfast was also associated with increased high beta activity, but less significant than the no- breakfast option. Most importantly, eating a nutritionally balanced breakfast was found to normalize the qEEG. The variation in high beta activity in the different breakfast options suggested that eating a nutritionally balanced breakfast may reduce anxiety and increase focus compared to skipping breakfast. These results may help explain why previous research has found cognitive, academic, and behavioral improvements when children consume breakfast. Furthermore, the qEEG should be considered in future nutritional studies as a measurement of brain function.