Or how energy dense fat is if you ignore the conversion efficiency. For this calculation they also assume the whole volume of the battery is filled with fat.<p>Humans actually aren&#x27;t that efficient in terms of conversion of chemical energy to mechanical work. Muscle is about 14-27% efficient at converting chemical energy to work, which is about as good as a combustion heat engine.<p>Now in terms of motion planning, image recognition, and &quot;cognition,&quot; humans tend to be more energy efficient than machines.