REVERSAL OF DIET-INDUCED OBESITY AND DIABETES IN C57BL 6J MICE/

We have previously shown that C57BL/6J (B6) mice develop severe obesit y and diabetes if weaned onto high-fat diets, whereas A/J mice tend to be obesity and diabetes-resistant. The purpose of this study was to d etermine if obesity and diabetes in the B6 mouse could be completely r eversed by reducing dietary fat content. After 4 months, both strains consumed more calories on a high-fat diet than on a low-fat diet, and both strains showed a higher feed efficiency (FE = weight gained/calor ies consumed) on the high-fat diet versus the low-fat diet. However, r elative to A/J mice, B6 mice demonstrated a significantly higher FE on the high-fat diet. Hyperglycemia, hyperinsulinemia, and increased adi posity were apparent in B6 mice after 4 months on the high-fat diet re gardless of whether the diet was begun at weaning or 4 months later. C orrelational analyses showed that adiposity was strongly related to bo th insulin and glucose levels in B6 mice, but only moderately related to insulin levels in A/J mice. In obese B6 mice that were switched to a low-fat diet, obesity and diabetes were completely reversed. Adiposi ty, fasting glucose, and fasting insulin values in these mice were equ ivalent to those in B6 mice of the same age that had spent 8 months on the low-fat diet. In summary, our data show that in the B6 mouse the severity of diabetes is a direct function of obesity and diabetes is c ompletely reversible by reducing dietary fat. Copyright (C) 1998 by W. B. Saunders Company.