Interestingly, circulating leptin levels are increased at 3 days on a HF diet indicating that the nutritional overload has been recognised [25], but are unchanged after 1 week on a HF diet, although body fat is significantly increased, indicating that nutritional overload, at this time, no longer evokes a leptin response and adiposity hasn't increased sufficiently to do so either. The gene discussed is LEP; the disease is hydrops fetalis.