Sloth
If energy efficiency were an Olympic sport, the sloth would win gold, silver, and bronze, provided the medals were delivered directly to its branch. The sloth's metabolic rate operates at roughly 40-45% of what would be expected for a mammal of its size, a figure that has caused considerable jealousy among marathon runners and efficiency consultants alike.
The Royal Society for Doing Absolutely Nothing has calculated that a sloth expends less energy in a week than a professional basketball player burns during a single timeout. This extraordinary parsimony extends to every aspect of sloth existence, including digestion, which can take up to thirty days to complete a single meal.
Basketball
Basketball is, by contrast, a catastrophically inefficient enterprise. A professional player may burn between 600 and 900 calories per game, energy that could theoretically sustain a sloth for approximately two weeks. The sport demands constant movement, repeated jumping, and the cardiovascular output typically associated with fleeing from predators.
The Oxford Centre for Sporting Metabolism has described basketball's energy profile as 'spectacularly wasteful,' noting that the same caloric expenditure could power a sloth's entire social calendar for a month, including their famously brief weekly toilet visits.
VERDICT
The sloth dominates this criterion with the quiet confidence of something that hasn't rushed since the Miocene epoch. Basketball's approach to energy - burning it as quickly as possible whilst running in patterns - represents everything the sloth has spent 64 million years evolving to avoid.