When I talk to people about calorie restriction, I usually have to remind them as we are talking that simply staying lean is not tantamount to being calorie restricted. This is an easy misunderstanding. People associate restricted calories with the goal of being thin because our culture imputes that goal to all diets. But our popular obsession with body mass index (BMI) is as much or more about looks than health. As a result, calorie restriction sounds to the average person like a very worthy objective but for the wrong reasons. 

A fixation with physical attractiveness will not likely sustain a calorie restriction lifestyle. The reason is simply not good enough to support the lifetime commitment that calorie restriction requires. CR is as much an educational program as it is a diet. Its real value lies beneath the surface; that is where the rich science is and the wonderful information regarding disease resistance and other incredible health effects. If you practice CR with these higher goals, chances are much greater that your decision will be permanent.

Furthermore, calorie restriction does not always produce a very low BMI. It's technically possible for someone whose calorie set point is very high to be 40% restricted yet still have an average BMI. Granted, as a general rule CR practitioners are very lean. But if the primary goal is to be lean, dieters are inclined to increase exercise when needed to compensate for excess calories. This is a perfectly appropriate strategy if your goal is a certain BMI. But this is perfectly inappropriate if the goal is calorie restriction. The fact that, because of exercise, a person looks in the mirror and on the scales as if he had not eaten what he had does not cancel the reality. The reality is that over time many more calories are consumed than would otherwise be the case. Calorie restriction research shows that the health benefits of CR hinges on the extent that calories consumed are below each person's set point. Burning off calories does not eradicate the fact that they were consumed. 

The bottom line is this: Do calorie restriction for the right reasons (there are a lot of them). Be prepared to undertake an educational process in conjunction with your new eating habits. Absent this, you are vulnerable to well-intentioned yet self-defeating habits.