According to the scientists, lower metabolic rates in dinosaurs compared to mammals helped them survive on less food, which also may have contributed to their enormous size. (ibtimes.com)
If you are sleep deprived you will lower your metabolic rate which means you wont be burning off as many calories. (scoobysworkshop.com)
This all leads to more fat and a much much lower metabolic rate. (liftingrevolution.com)