Another way of saying 'less on the original energy?'.

I need to re-phrase it.

Please give us the entire sentence and then we may be able to help you.

They are getting less on the original energy.

They (?) are getting less what? What do you mean by "original energy?"

People are getting less of the original amount of energy.

Your sentence is o.k. the way it is.

To re-phrase the phrase "less on the original energy," you could say "reduced energy from the starting point" or "diminished original energy."