I understand what you're saying after reading this comment, but the quotation below still seems unclear.

It is standard practice - by those in the know - to use restricted animals as controls in CR experiments

"Dietary energy restriction", "calorie restriction", "CR" and "restricted" were intended as synonyms.

With no distinction between restricted and calorie restricted, it seems like you are saying that in Calorie Restriction experiments the control group mice are on calorie restricted diets, as presumably are the test group mice. This is confusing to me.

I understand now (the control group mice are restricted but less so), but maybe the first comment could be edited for better understanding?