I have pointed out in other articles the striking contrast between, on the one hand, the feverish interest shown calorie restriction by scientific researchers and, on the other, the virtual invisibility of CR amid a population otherwise obsessed with dieting. As I have elsewhere opined, I think the latter is largely due to a failure on the part of those who do know (but whose expectations are cynically low) to inform and educate those that don’t.    

Meanwhile, expectations are very high among those studying the nature and effects of calorie restriction. Since 1935, when Clive M. McKay at Cornell University first stumbled across the CR phenomenon, over 1000 CR-related studies have been conducted at major universities around the world. These studies generated over 100 articles in prominent medical and other scientific journals, including JAMA, Lancet and New England Journal of Medicine. This vast and prolonged scientific gold rush was triggered by a very concrete discovery: When an organism, for example an animal, consumes substantially fewer calories (20-40%) than it normally would, its lifespan is extended beyond the maximum lifespan for its species.

This was an earth-shattering discovery. To fully appreciate this assertion you need to understand the difference between average life span and maximum life span. When health experts speak of ways to lengthen your life, to add years to your life, they are referring to ways that you can increase your average lifespan. In other words, no one can accurately tell you that a given behavior or product will extend your life in particular. The fact is that you in particular may die tomorrow in a plane crash or next year from a rare genetically-determined cancer. What experts can tell us is that certain things will increase the average health and longevity among members of a given population. There are a lot of these things: stop smoking, exercise regularly, eat lots of fruits and vegetables, use a seat belt. Studies show conclusively that when applied among a large representative sampling, the average life expectancy is higher. 

While this is interesting and very valuable information, it pales in significance when compared to the things that allow an organism’s lifespan to plunge through the ceiling of its species, i.e. to surpass the specie’s maximum life span. For example, look at the most popular conventional strategy for increasing average lifespan: aerobic exercise. Beginning in the early 1970s,  Dr. Kenneth Cooper and other influential proponents have persuaded many if not most educated Americans to either exercise regularly or feel guilty that they don’t. While the health benefits of aerobics can be measured in more than one way, the longevity effect is probably the most telling. Furthermore, since the runners have been running now for almost 40 years, the jury is in regarding the impact of aerobics on average lifespan.

Though there is room for disagreement regarding the details, the bottom line is that we are talking about single digit gains. This has been the nature of health discoveries after the middle of the last century. In the hundred or so years before there were quantum gains attributable largely to advances in environmental safety and infectious disease control (e.g. vaccinations, antibiotics, sterilization). But these were low hanging fruit that related less to our body’s intrinsic capabilities than to external threats. Going forward, as our present average exercised life span of 80 years encroaches on the human maximum life span of 115 years, gains are likely to become more effortful and incremental before finally butting against the brick wall.

Consequently, the real action, scientifically and commercially speaking, relates to the metabolic changes triggered by calorie restriction but without the restriction of calories. The truly good news is that such a metabolic phenomenon even exists. Except for calorie restriction, there would be widespread skepticism among scientists that its even possible to extend the life of an organism beyond its maximum life span. Such things were discussed more in science fiction than science. Now that we are past that hurdle, the frenetic race is on. Meanwhile, as the research proceeds, discoveries are occurring along the way that require medical professionals to think differently about the diagnosis and treatment of disease. Following are a couple of interesting examples:

  1. Traditionally, physicians have considered a patient’s white blood cell count (also called “leukocytes”) a very important indicator of his immune health, of his ability to fight off various diseases and infections. Standard lab tests measuring white blood cell counts consider a count below 4,500 white blood cells per microliter (mcL). an unfavorable marker which indicates the immune system is impaired, that the patient has a greater vulnerability to disease. Yet calorie restriction studies show that CR subjects consistently have  white cell counts substantially below the reference range while demonstrating exceptionally effective immune function. In the human study presently being conducted at Washington University in St. Louis, in which I am a participant, virtually all the CR subjects show medically low white cell counts yet are much healthier than their non-CR counterparts. They also report fewer colds and other illnesses as well as fewer allergies now than before CR. (Further investigation suggests that the answer likely lies in a sub-group of cells. CR practitioners, while low regarding all white cells, are actually very high respecting this particular subgroup. If this theory is confirmed it will explain the CR white cell paradox as well as inform the  medical profession of a long-standing diagnostic error.
  2. Bone health has traditionally been determined by measuring a person’s “bone mineral density”(BMD). The is done with a special x-ray device which measures the mass of the bone. If someone’s BMD is more than one standard deviation less than that of a healthy young adult, he is said to have osteopenia, generally considered a call to action if one is to head of the dreaded diagnosis of osteoporosis,  defined as more than 2.5 standard deviations from the reference BMD. A low BMD is considered an indicator of weak bones and an accompanying higher risk of fracture. Calorie restriction research, however, suggests that BMD is not a reliable test of bone health. The human CR study at Wash U has studied closely the bone health of the CR participants and has found them to have functionally strong bones despite low BMDs. None of the participants have reported any fractures or other such problems despite substantial levels of activity. As with low white cell counts, practitioners of CR consistently have lower BMDs than their more caloried counterparts. Researchers believe that the bone loss that a person experiences when he adopts CR is akin to the myriad other adaptations that the body makes as it becomes increasingly efficient and healthy. 

    Bones are dynamic organs and it turns out that their mass expands and contracts with changes in the body’s structural and other needs. If someone is carrying 300 pounds of body weight, for example, he will require larger bones than the same person carrying 150. The body is smart enough to sense such changes and to make appropriate adjustments. What is most interesting, however, is that bone strength, integrity, does not appear to have been compromised through such adaptations despite the loss of density. Clearly this suggests that the gold standard for measuring bone health, BMD, needs to be replaced, along with the indiscriminate standards regarding treatment of osteopenia .  

This  is a Freudian obsession of modern origin, a by-product of Western affluence. People in the West face a grave dilemma: On the one hand, they have  an unlimited, almost historically unique, opportunity--They can eat whatever they want whenever they want. Lest they forget, wonderfully tasting food is continuously displayed around them wherever they may be.  

On the other hand, if they allow themselves to eat as they desire they will soon find themselves fat, sick and dead. So what is the solution of choice to this dilemma? 

Is it an admirable display of discipline? Is it a thoughtful reassessment of life's priorities? No, it turns out modern consumers prefer something much more elemental: a faster metabolism. This is the next best thing to the fountain of youth--the apparent fountain of youth. Its the unrestricted calorie diet, CR in drag. 

Unfortunately, despite appearances, this is the antithesis of calorie restriction. CR induces the body to become maximally efficient, to get more done with less, to operate on less fuel than it otherwise would. We don’t know completely how calorie restriction accomplishes this result. But we  do know that when calorie restricted, the mitachondria (which produces energy in the cells) produces much less waste, the heart rate slows, body temperature drops and metabolism slows. These adaptations are all very positive for health and longevity. 

By contrast, the popularly proclaimed “fat-burning metabolism” produces the opposite. By definition it is designed to get the least done with the most energy, to consume the most calories possible for bodily operations. Does this sound like a desirable condition long term?

This is like shopping for an automobile designed to get the fewest miles per gallon possible. Such an automobile would discharge into its environment much more waste and pollution than its more efficient counterparts. That is exactly what the body must do with its metabolic waste, except that its environment includes the cells and systems of the body.

CR research traces to these processes much, if not most, of the diseases of affluence claiming the lives of most Americans today (i.e. cancer, heart disease and diabetes). Yet, because an over-active metabolism holds the promise of more food for a given waist line, modern Americans persist in their pursuit of products purporting to deliver this effect.  Not surprisingly, the few small voices advocating intelligent eating lifestyles cannot compete with the baser impulses of consumers and the industry that serves them.  

The bottom line is that people in the end make choices that reflect their priorities. If health and longevity are important priorities, calorie restriction is appealing. If not, there is at least the security to be found in numbers. In a manner of speaking, one might even claim the weight of opinion. I’m reminded of a Bible verse to the effect that “wide is the gate and broad is the path that leads to destruction...”; hmm, food for thought.

Calorie Restriction Transition


Hopefully you have been favorably impressed by what you have heard and read about calorie restriction. You may have even decided that this is what you want to do for the balance of your life. But you are not sure where or how to start. Here are a two critical points that can make the difference between health and disaster:

  1. Adopt calorie restriction gradually. Animal studies clearly show that an abrupt commencement of a calorie restriction diet actually reduces rather than enlarges life span. This makes complete sense if you think about it. Calorie Restriction produces a condition in your body that does not occur over night. We know that when calorie restricted, you body becomes much more efficient. Your body temperature drops 1-4 degrees; Your heart rate slows; Your blood pressure drops; Numerous other body functions adapt to the new caloric environment. Your body cannot accomplish changes, adaptations such as these overnight. 

Have you ever known or read of someone who has climbed Mount Everest? Often people wonder why a expedition like that is a 2-3 month event when the actual climbing itself is a 3-4 day event. The answer lies in the physiological adaptation required of the body to survive at altitudes above 21,000 feet. It is a wondrous commentary on the body’s capacity to adapt that it can learn to survive on 33% of the oxygen that it would otherwise require. But this adaptation is not instant. In fact if a climber were to skip the acclimatization phase of his climb, he would be dead long before reaching the summit. Put differently, if a climber were simply deposited on the summit of Mt. Everest, he would be dead within minutes.

Your body’s adaptation to calorie restriction is similar to acclimatization. The body is willing and capable of adapting to new, more challenging conditions so long as it is given the opportunity to do so at the pace it requires. While there is no firm rule here and the animal studies may require some adjustment for our purposes, there are some general rules that those of us doing calorie restriction have followed. Most of us have followed the advice of Dr. Roy Walford, an early CR leader and scientific authority (incidentally, I highly recommend his book, “The 120 Year Diet”) which suggests an adaptation period of 6-12 months. This means that you should  titrate your calorie restriction so that you arrive at your eventual restriction goal (for example, a 25% reduction in daily calories consumed) at the appropriate point in the future (for example, 6 months later). A good indicator for those who are significantly overweight at the start is the rate of weight loss. Your weight loss should parallel your calorie restriction. In other words, the loss should be dispersed evenly over the adaptation period. Resist the temptation to shed weight rapidly. This is the tactic of commercial diet schemes whose horizons are measured in days and weeks. Calorie restriction is permanent; its about the rest of your life. That is all the more reason to do this right. Be patient.

  1. Determine your particular set point before you start restricting your calories. When starting calorie restriction, people are tempted to plunge forward before getting a point of reference regarding their pre-CR calorie consumption. This requires some explanation: Calorie restriction, as it relates to longevity and health, refers to reductions in calories below an organism’s particular “set point”. The “set point” is the number of calories that the organism (you, for example) would choose to consume if eating entirely without inhibition. In other words, how many calories would your body request each day if given its unfettered preference (i.e. while neither dieting nor gorging)? 

    Each of us has a metabolism which is designed or conditioned to operate at a certain level. Some of us have very active metabolisms that prod us to eat more than those whose metabolisms are much slower. As a result, some of us gain weight more easily than others. Appetite, however, is more complicated and involves additional factors that no one fully understands. What we do know is that set points are very individual, as are their corresponding body weights. This is why you cannot identify a calorie restriction practitioner by his body weight. While it’s generally true that CR practitioners are very lean (my BMI is 18), it’s not necessarily true.  Think about it: If you are 5’8” and weigh 250 lbs. before CR (which we will assume reflects your set point calorie consumption), after a 30% calorie restriction your weight might settle in the 175 lbs. range. That’s not exactly lean. One can argue, of course, that there is room for further restriction in such circumstances, that you should reduce you calories even more. Perhaps that’s true. But the scientific research suggests that the chunky calorie restrictor in my example should indeed experience some, if not all, of the benefits enjoyed by his leaner 30% restricting counterpart.

Therefore, begin your calorie restricted life by eating without restriction. Do this for      four to five days while carefully counting your calories. Use these figures to calculate your daily average, which will constitute your set point. 

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.

One thing that I have noticed since I began calorie restriction some eight years ago is this: A lot of cynicism exists among researchers and practitioners alike regarding calorie restriction’s potential appeal to the general public. In fact, it’s this attitude that largely explains the amazing multi-decade neglect shown calorie restriction by all involved. It helps explain how a discovery so incredible could shuffle along for 70+ years without acknowledgement from the media, this despite feverish interest on the part of the scientific community. The lab excitement, incidentally, relates to the general public only indirectly: Research teams around the world are frantically in pursuit of the pharmacological elixir that can simulate the calorie restriction metabolic effect in human beings. This is the Holy Grail that promises riches to its patent holder and health and longevity to its paying customers. To this end, millions of dollars are spent each year by privately funded researchers on calorie restriction-related research. 

I don’t object to the mercenary motives here. Adam Smith’s “invisible hand” earns its keep. My lament here is that the calorie restriction researchers have generated some really exciting and practical information that is useful today to people willing to seize it.  Yet this information is not being shared with the general public. That is not to say that it is a secret or that any conspiracy is afoot.  In fact, this information appears regularly in scholarly journals, including medical journals such as JAMA and New England Journal of Medicine. Literally thousands of calorie restriction experiments and studies have been conducted at major universities and research laboratories around the globe over the past 70 years. Much of this research has been published and is easily retrievable for those of us willing to expend the time and effort to locate and understand it. But why is this necessary? Where are the otherwise officious voices and resources of government, the medical community, the press and others when we can really use them? Instead, we have gotten the collective paternalistic sigh that says, “No one is going to do a diet like this.  This diet is too radical” (that is, as compared to the mainstream but non-radical gravy/burger&donut diet). Consequently, science and evidence notwithstanding, it’s considered a waste of time and resources to promote this diet to a notoriously food-fond American public. One might as well cast pearls before swine (pardon the pun).


So let’s test this conclusion. We will use you as an example. Let’s pretend that you had  not heard about calorie restriction, but that you are like many people in that you have an interest in health and fitness, that within reasonable boundaries you want to do the right and smart thing (the premium plan).  Meanwhile, you are going about your life with the proposition in mind that smart and reasonable people hold about their health: i.e. you should 1) avoid obesity at all costs,  2) limit desserts and fried foods (especially those with trans-fats) while preferring fruits and vegetables.  3) exercise as much as Rule #1 requires.  

Yet these axioms are tempered by your real world experience. You see cancer, heart disease and diabetes all around you -even among those on the premium plan. Furthermore, its very hard to push away from the table when you are still hungry and there is still plenty of food. Meanwhile, medicine is good and getting better at contending with the consequences of an imperfect diet. Besides, no one lives forever (put differently, the longevity payoff is not that great). So even the conventional premium plan fails to inspire great devotion because of this pay-off problem. 


Now let’s imagine that one day while eating a blueberry croissant at Barnes & Noble you happen upon a very bold but fascinating diet book. This book reveals to you a well-documented strategy for dramatically reducing your risk for virtually every major disease while increasing your remaining years 30-50%.  With this plan you will likely live 25+ additional years with wonderful health and functionality. This means that the life you had planned will now likely be much longer, much better and much more certain. But there is a price: You must be willing to consistently monitor your calories to assure that they do not exceed a certain level. That level will be 25-30% lower than you would otherwise choose. Furthermore, you must be willing to eat foods that are more healthful than you might have otherwise chosen. If you read further, however, it turns out that the sacrifice is not as draconian as you might think: By choosing the most nutritious foods, plant foods, you can in fact eat much more food than you otherwise would. 


There you have it. That’s the pitch in a nutshell. Was the elite cynicism well placed? Or does CR sound like something you want to know more about? More to the point, is it conceivable to you that you could live with the calorie restriction plan? I know I lost some readers at “...there is a price”. I lost others at “...consistently monitor your calories”. But I know that there are many others, you for example, who have hung with me to this point and whose interest I’ll bet is genuinely piqued. Hopefully, you are nodding your head (as opposed to your head nodding) at his stage and are at least persuaded of calorie restriction’s modest  popular potential. And that’s the basis of my complaint: As to life’s most important decisions (life and death among them), people deserve the opportunity to make tough but smart decisions. At a minimum, this requires information-- not simple disclosure in the technical, academic journal sense, but active, even evangelistic, dissemination. But this proportionality is entirely missing with calorie restriction research. As a result, people otherwise receptive to calorie restriction live shorter less healthy lives. The fact that we can’t quantify this omission- i.e., that we don’t know their numbers, the diminution of their years or the gravity of their diseases- doesn’t diminish its grave and substantial consequences.