Research from the Priceton Neuroscience institute suggests that animals show signs to addiction to sugar such as craving and relapse.  The research conducted in the department of Psychology, encourage rats to 'binge' on a sugar solution in addition to their normal diet.  After a month on this diet, the rats had adpated to higher levels of dopamine (a brain chemical produced as a result of pleasurable sensations such as eating). The rats were then subjected to a prolonged period without sugar. When sugar was reintroduced the rats worked harder than previously to obtain the sugar and their consumption increased.  Withdrawal symptoms were observed in the rats when they were deprived of sugar. These included a fall in dopamine levels and chattering teeth.  The research team believe their findings may help in the understanding of eating disorders.