Food is not gasoline, it does not "burn" better to give you more energy. If you want energy, eat a spoon of sugar and you will have all the energy you need for the next hour, in its purest form. Meat mostly has proteins and fats used for building things and not for energy. Protein and fat requirements are pretty low and body has decent reserves in addition to reusing allot from its own dead cells. Sensation of tiredness comes from hormonal problems. I suggest you look in to fasting, those help allot.