Not that I imagine there are many people out there under the impression that calorie restriction (CR) replaces the need to exercise to maintain good health ... but it never hurts to keep hammering nails into these coffins as they drift back into immediate reach.
Those who dieted lost muscle mass while those who exercised did not. This is because exercisers routinely challenged their muscles, which prevented muscle tissue from degrading. Dieters didn't work their muscles as vigorously as those who exercised. ... It's important that dieting not be seen as a bad thing because it provides enormous benefits with respect to reducing the risk of disease and is effective for weight loss. Furthermore, based on studies in rodents, there is a real possibility that calorie restriction provides benefits that cannot be achieved through exercise-induced weight loss." So then, as before, and as CR practitioners do, the best way forward would seem to be some combination of CR and exercise, not one or the other.
The topic of exercise, bone loss (rather than the muscle loss above) and calorie restriction has been in the popular science press of late. A recent study on the subject is referenced over at Ouroboros:
A recent study addresses the effect of CR on bone loss, and finds that limiting caloric intake can result in decreased bone mineral density (BMD) at clinically relevant sites in the body, i.e., places where fractures often occur in the elderly. ... These data suggest that [exercise] should be an important component of a weight loss program to offset adverse effects of CR on bone.
It really isn't hard to come to an 80/20 benefit situation in personal health - and thereby increase your chances to living into the coming era of working anti-aging medicine and the end of age-related frailty. The basics of good health and maintenance are not rocket science; eat less, eat the right levels of nutrition, modest supplementation and exercise. If, like many people, you treat your body worse than your car, you might stop for a moment and ask yourself just what the cost of that course might be - is it worth it?
In the Epicurian world of the past, in which there was no possibility of extending the maximum human life span through science, there was little to said in criticism of those who chose to burn their candle faster. But we don't live in that world anymore; science is advancing so rapidly that modest differences in your expected healthy life span today could lead to enormous consequences for your future. Will you miss the advent of the first therapies capable of repairing age-related damage and restoring a degree of youth? Or will you make it with a few years to spare? We are fortunate to be in the midst of the early stages of a transformative revolution in science and medicine; to those cutting their lives short, I feel we have some obligation to ask "are you sure you know what you are doing?"