Went without food, limiting energy? Just the opposite (7)
I believe the answer is:
feasted
'just the opposite' is the definition.
I can't tell whether this definition defines the answer.
'went without food limiting energy?' is the wordplay.
'went without food' becomes 'fasted' (I've seen this before).
'limiting' indicates putting letters inside.
'energy?' becomes 'e' (physics symbol as in E=mc2).
'fasted' placed around 'e' is 'FEASTED'.
(Other definitions for feasted that I've seen before include "Banqueted" , "Ate lavishly" , "Had a lot to eat" , "Ate high off the hog" .)