Looking at the details of calorie restriction

I've talked to a few nutritionists lately who insist that longer lifespans and overall healthier lives can be had by restricting overall caloric intake. Since eating is a social and mental undertaking that happens to manifest itself in physical health, one must be vigilant in calories every single day. Few have this overall discipline I think. Well, unless you're a nutritionist.

A recent study looked at calorie-restricted diets and how they differed in overall glycemic loads -- but ended up resulting in comparable long-term weight loss. In other words, there is more than one solution to the problem of weight loss and multiple and somewhat equal methods. Do you agree?