The effect of intermittent glucose administration on the circadian rhythm of body temperature was studied in rats to provide evidence of sugar addiction, withdrawal and relapse. Metabolic and behavioral phenomena were also observed. Biotelemetry transmitters recorded body temperature for the duration of the 4-week experiment. Rats were divided into an experimental and a control group, which were maintained on the same habituation conditions for the duration of the experiment, with the exception of weeks 2 and 4, when the experimental group was presented with a 25% glucose solution. Experimental animals displayed a precipitous drop in body temperature and behavioral changes associated with withdrawal during week 3, when sugar was removed. There was an increase in kilocalories (kcal) consumed during weeks 2 and 4 by experimental animals and, by the end of the experiment, these animals showed a greater percent increase in body weight. Elevated blood glucose levels were found in experimental animals. The study demonstrates that the effects of sugar addiction, withdrawal and relapse are similar to those of drugs of abuse. Implications of the rewarding and addicting effects of sugar are related to weight gain, obesity and Type II diabetes. Furthermore, pitfalls related to dieting are elucidated.