I advocate calorie restriction (CR) as a Good Thing, assuming your physician agrees, as I'm sure regular readers know by now. The health benefits have been more than adequately demonstrated, and there is the strong likelihood of increased longevity based on decades of animal studies and a few tantalizing human results. Of course, you'll also lose weight - but this is something of a side-effect for CR practitioners rather than a goal to be attained for its own sake. Since starting my advocacy of CR, I've heard numerous anecdotes regarding the difficulties that more overweight - or obese - people have with the practice of CR; it seems that different dietary and lifestyle strategies are more effective at weight loss above a certain weight (varying by person). Once you get down to a more reasonable weight, calorie restriction becomes easier. Or so they say.

While wandering the wilds of the web today, I came across a summary of a much more rigorous treatment of this phenomenon and thought it worth sharing.

Without hard data, I've relied on the idea that the Basal Metabolic Rate (BMR) in metabolism may be the trigger for a "conservation of energy" in the human body. That taking daily calories below the BMR triggers what many call "starvation mode" in the metabolism - that is, the body starts to use less energy as it prepares to survive what it perceives as a famine condition.

My recommendation has remained consistent over the years - one must try to determine their BMR and eat enough calories to meet that calorie requirement for basic function so the body will allow for loss of its stored energy - fat on the body. Interestingly, the BMR of most people is much higher than they realize and certainly higher than the often recommended calorie-restriction of 1200-1600 calories per day for weight loss.

The article goes on to discuss and explain the significance of a recent study on some biochemical details of calorie restriction and weight loss. Interesting stuff. The information to take away with you would seem to be that at a given weight, there is an optimal level of caloric intake that will convince your body to process stored fat rather than hoard it or layer on more. The more fat you have, the more calories you need in order to hit this optimal intake. If this level is much higher than the level of caloric intake for an out-of-the-box practice of calorie restriction, then you will likely have difficulty jumping right on in. A more gentle ramping down of calories might be called for, as well as trial and error testing of your metabolic response to different levels of caloric intake - as more experienced calorie restriction practitioners would advise in any case. As with many other things, patience, research and experimentation will win through in the end.

If you're new to calorie restriction, I recommend picking up a copy of The Longevity Diet; I think you'll find it very helpful.

My final, anecdotal, contribution: regular exercise makes all the difference to your efforts, leading to large changes in the response of your body to different levels of caloric intake. Try it and see.

Posted by Reason at August 27, 2005 1:07 PM | TrackBack (0)