An article about the pitfalls of using mice for animal research leads off with the example of calorie restriction. The controls for calorie restriction mice experiments were obese mice, suggesting that the health benefits of calorie restriction might be conflated with the health benefits of not being obese. I get the impression that people who study calorie restriction still think it worthwhile for life extension, but it's useful to try and integrate all evidence you come across.
[edit] timtyler suggests this is a well-understood effect that's already been taken into account by CR scientists.
It is standard practice - by those in the know - to use restricted animals as controls in CR experiments - in order to help to avoid this criticism. The controls actually need to live longer than normal, to help prove that the researchers haven't screwed up somewhere with diet, conditions, pathogens - or whetever.
Some researchers don't do this - and their evidence is promptly discarded by those who understand the issue.
Anyway, it hardly seems fair to bill this effect as "Evidence against Calorie Restriction". This is a well-known and well understood effect for those in the field. Dietary energy restriction enthusiasts are not basing their diet on this kind of screwed-up evidence in the first place.
Good! I was hoping this would be the case.