Approximately 40% of the energy stored in sugar molecules is converted into energy. what happens to the remaining 60%?

Approximately 40% of the energy stored in sugar molecules is converted into energy and the remaining 60% is wasted as heat energy.

Cellular respiration is the process which take place inside a living organism by which organic compounds, usually carbohydrates, are broken down releasing energy that is used to produce ATP molecules that supplies energy/power to cells.

C6H12O6 + 6O2 —– enzymes & coenzymes ——> 6CO2 + 6H2O + Release of Energy (≤38 ATP) + Heat

So, 40% of the available energy of glucose is release as ATP and the remaining 60% is lost as heat and helps to generate your relatively high body temperature.