How the Brain Decides What to Eat

Researchers have been performing a study on fruit flies and what they consume. Carlos describes their findings, 'Normally when kept on "complete food" (with sugar and yeast) and given the choice, flies do not eat food with proteins (yeast-enriched). However, after a few days on a protein-poor diet, flies preferred a yeast-rich diet. Female flies switch diets more quickly than males, and mated females quicker than virgin females. The researchers used a simple and clever assay to follow the type of food flies preferred: they added a blue dye to the yeast-enriched food and a red dye to the 'sugar rich food', and then looked at the bellies of the flies, to know which food they had eaten. Research in the fruit fly has helped unravel several mechanisms which proved to be relevant in humans, too. This study appears to be on the same track.

http://www.sciencedaily.com/releases/2010/05/100513123827.htm