How efficient is the human body at converting food energy into mechanical energy via the muscles on average?

Question

as in % efficiency

Answer 1

Basal metabolic rate (BMR) is the amount of energy expended while at rest in a neutrally temperate environment, in the post-absorptive state (meaning that the digestive system is inactive, which requires about twelve hours of fasting in humans). The release of energy in this state is sufficient only for the functioning of the vital organs, such as the heart, lungs, brain and the rest of the nervous system, liver, kidneys, sex organs, muscles and skin.

Energy expenditure breakdown
liver 27%
brain 19%
heart 7%
kidneys 10%
skeletal muscle 18%
other organs 19%

As an example, for a 55-year-old woman, an estimated BMR might be 32 kilocalories (kcal) per square meter per hour. If her body surface area were 1.4 m², the hourly energy expenditure would be 44.8 kcal/h (32 kcal/(m²·h) x 1.4 m²). This amounts to an energy expenditure of 1075 kcal per day (44.8 kcal x 24). The value of 1075 kilocalories, then, is the resting metabolic rate; or, if the more stringent measurement conditions were met, it could also be the basal metabolic rate.

Answer 2

The digestive system takes at least 60% of the energy just to digest so this energy is not even used so i'd say between 30-40%

Answer 3

if we were fuel for a machine ex bicycle we would be 24% efficent. gasoline is 52%

Answer 4

A lot.