Scientists from McGill University in Montreal, Canada, have isolated the gene in mice that turns bad (white) fat into good (brown) fat. In a study published in Nature Medicine 2001 (pp. 1102-1103, 1128-1132), Dr Nahum Sonenberg and his colleagues explained how they were able to create leaner mice, which could eat as much as fatter mice, by inactivating a metabolism-related gene that encodes a protein called 4E-BP1. With this gene gone, the animals' bodies converted some of their fat stores into a more weight-friendly fat that promotes calorie burning. Overall, the study found that mice without the 4E-BP1 gene weighed about 10% less than normal mice, despite eating the same amount of food.