Timing of fructose intake: an important regulator of adiposity.

1. Overconsumption of fructose produces glucose intolerance, autonomic abnormalities and renal dysfunction and may be related to the worldwide epidemic of obesity and diabetes. 2. Experiments were conducted to determine whether the time period (light or dark) of fructose consumption influenced the pathological consequences. C57BL mice were given standard chow and assigned to one of three groups: (i) control (n = 10), which received water over a 24 h period; (ii) FL (n = 11), which received 10% fructose solution during the 12 h light period; and (iii) FD (n = 11), which received 10% fructose solution during the 12 h dark period. 3. There was a time related increase in body weight for all groups (P < 0.01, 2 vs 6 wks). There was a greater increase in body fat in the FL group compared with the control and FD groups. The changes in adiposity occurred even though the total caloric intake was not significantly different among the groups (approximately 18 kcal/day). Total fluid (water + fructose) consumption was greater in the FD and FL groups compared with control at 6 weeks. Significant increases were noted for plasma insulin and leptin at 8 weeks, with highest levels in the FL compared with FD group (P < 0.05). There were no significant changes in glucose, glucose tolerance, cholesterol, triglycerides or adiponectin. 4. The results of the present study suggest that there is a mismatch in caloric consumption, metabolism and adiposity as related to the light-dark cycle of fructose consumption. These findings have clinical implications in the control of bodyweight, abdominal fat accumulation and Type 2 diabetes.