Calorie Restriction: My Theory and Practice

Like most fu­tur­ist-ori­ented peo­ple, I am fas­ci­nated by the idea of long-term life ex­ten­sion—the no­tion that even­tu­ally peo­ple will have life ex­pec­tan­cies of hun­dreds of years; thou­sands of years; or even more. Although medicine has a ways to go in this area, one ob­vi­ous ap­proach is to take low tech steps to in­crease one’s lifes­pan in hopes of liv­ing long enough to take ad­van­tage of pos­si­ble fu­ture ad­vances. i.e., to roll with +1 dice. Be­sides the ob­vi­ous steps like wear­ing seat belts; get­ting reg­u­lar ex­er­cise; eat­ing a lot of fruits and veg­eta­bles, calorie re­stric­tion pre­sents it­self as an in­trigu­ing pos­si­ble method of life ex­ten­sion.

In this es­say, I will at­tempt to briefly define calorie re­stric­tion; as­sess how use­ful it might be; spec­u­late about how it might be use­ful; and use the fore­go­ing to jus­tify my own per­sonal ap­proach to calorie re­stric­tion, which I will de­scribe presently. Of course I wel­come com­ments and crit­i­cisms, es­pe­cially since I am mess­ing around with my own health.

I should note at the out­set that I have no for­mal train­ing or cre­den­tials in medicine nu­tri­tion or any­thing like that. I’m just an at­tor­ney.

I should also add that my ap­proach to calorie re­stric­tion is not a diet in the sense of be­ing a weight loss strat­egy for peo­ple who can­not con­trol their eat­ing. This is not a weight loss post! I do not de­scribe in this es­say how I con­trol my eat­ing; con­trol is as­sumed.

Last, my gen­eral ap­proach is one of no re­gret. i.e. My main pri­or­ity in calorie-re­strict­ing my­self is to avoid do­ing any­thing too rad­i­cal in terms of loss of qual­ity of life or risk to my health.

I. What is Calorie Restric­tion?

Wikipe­dia defines “calorie re­stric­tion” as fol­lows:

Caloric re­stric­tion (CR), or calorie re­stric­tion, is a dietary reg­i­ment that is based on low calorie in­take. “Low” can be defined rel­a­tive to the sub­ject’s pre­vi­ous in­take be­fore in­ten­tion­ally re­strict­ing calories, or rel­a­tive to an av­er­age per­son of similar body type.

So im­me­di­ately we see a prob­lem—the con­cept of calorie re­stric­tion is am­bigu­ous. How am I sup­posed to eval­u­ate and pos­si­bly im­ple­ment calorie re­stric­tion in my life if I am not even clear on what it means? This is not just a prob­lem for lay­men like me. Imag­ine you are a re­searcher who is study­ing the effects of calorie re­stric­tions in lab chimps. How do you feed your con­trol group of lab chimps? Do you let them eat donuts and potato chips ad libi­tum? Do you limit them to chimp chow? Without a clear defi­ni­tion, this is a bit of a co­nun­drum.

In fact, one in­di­vi­d­ual has ar­gued that the differ­ence in treat­ment of con­trol an­i­mals may be part of the rea­son why two stud­ies on calorie re­stric­tion in mon­keys had differ­ent re­sults:

Fur­ther, the NIA study con­trol mon­keys were not truly fed ad libi­tum, un­like the WNPRC study. The reg­u­lated por­tion­ing of food for the NIA con­trol mon­keys may be a slight re­stric­tion and, thus, largely pre­vented obe­sity. Stud­ies of 10% CR have been re­ported to in­crease lifes­pan in rats com­pared to ad libi­tum con­trols – even more than 25% and 40% CR20. The NIA con­trol mon­keys may ex­pe­rience sur­vival benefits from this slight re­stric­tion.


Another in­di­vi­d­ual states as fol­lows:

Both the NIA and U Wisc stud­ies need to be con­sid­ered to­gether for proper in­ter­pre­ta­tion. It is clear that the U Wisc “con­trols” differ from the U Wisc CR group and BOTH NIA groups, and are prob­a­bly most like the gen­eral pop­u­la­tions of de­vel­oped coun­tries.

Be­cause we at NIA wanted to avoid the crit­i­cism lev­eled at many ro­dent CR stud­ies that con­trols are over­weight and seden­tary, we speci­fi­cally de­signed our dietary con­di­tions to sup­ply an ad­e­quate, but not OVERad­e­quate, caloric in­take.

The bot­tom line is that, for most peo­ple (who are more like the U Wisc con­trols), CR may in­deed provide both health (BOTH stud­ies agree on THIS) and longevity benefits.....and of course, most im­por­tant.....more “healthy years.”


For pur­poses of this es­say, I will offer the fol­low­ing defi­ni­tions:

1. “Mild calorie re­stric­tion” = re­strict­ing calories suffi­ciently so that you avoid gain­ing large amounts of weight.

2. “Moder­ate calorie re­stric­tion” = re­strict­ing calories suffi­ciently so that most of the time you are to­wards the bot­tom of your metabolic range.

3. “Se­vere calorie re­stric­tion” = re­strict­ing calories suffi­ciently so that you end up spend­ing your time sig­nifi­cantly be­low typ­i­cally fit peo­ple in terms of mus­cle mass and/​or body fat.

The first and third defi­ni­tions are pretty straight­for­ward, al­though it’s worth not­ing that a lot of peo­ple en­gage in mild calorie re­stric­tion un­in­ten­tion­ally, just through the op­er­a­tion of their nat­u­ral sys­tem which reg­u­lates their ap­petite/​urge to eat/​urge to stop eat­ing (John Walker calls this the “food clock.”)

The sec­ond defi­ni­tion re­quires a lit­tle ex­pla­na­tion. From sim­ple ob­ser­va­tion, it ap­pears that small changes in one’s en­ergy in­take re­sult in cor­re­spond­ing changes in one’s metabolic rate. So that if your weight is sta­ble but you eat a lit­tle more or less than usual, you might no­tice that you are a lit­tle warmer or cooler than usual. Ev­i­dently the body can and does make small ad­just­ments to its metabolic rate in re­sponse to changes in food in­take. This is also con­sis­tent with dieters’ re­ports that they feel cold when diet­ing.

II. Does Calorie Restric­tion Work in Hu­mans?

It seems quite likely that mild calorie re­stric­tion works in hu­mans based on the ob­ser­va­tion that fat peo­ple have sig­nifi­cantly greater mor­tal­ity than thin peo­ple.

For ex­am­ple, as illus­trated by the charts here:


Of course one can­not know this for sure since there is no eth­i­cal way to do a large con­trol­led ex­per­i­ment, but still it’s rea­son­able to in­fer cause and effect: Com­mon sense says that be­ing fat puts a lot of ab­nor­mal ex­tra strain on your sys­tem al­most all the time. In any event, there seems to be lit­tle down­side to mild calorie re­stric­tion.

A more in­ter­est­ing ques­tion is whether mod­er­ate calorie re­stric­tion works in hu­mans. Com­mon sense says that it ought to be benefi­cial based on the idea that slow­ing one’s metabolism ought to slow the ag­ing pro­cess, all things be­ing equal. One in­ter­est­ing area of re­search is stud­ies which look at the effect of mod­est weight loss among obese peo­ple. Is some­one who goes from 250 pounds to 225 pounds and stays there more healthy than some­one who goes from 210 pounds to 220 pounds and con­tinues to gain weight? If so, part of the differ­ence might be that the sec­ond per­son is to­wards the top of his metabolic range while the first per­son is to­wards the mid­dle or bot­tom.

The Calorie Restric­tion So­ciety web site links to a cou­ple pre­sen­ta­tions which ar­gue that can­cer is ac­tu­ally a metabolic dis­ease re­lated to hav­ing too much en­ergy in play. I’m a bit skep­ti­cal of this claim, but it does seem to me that you are invit­ing trou­ble by hav­ing ex­tra en­ergy float­ing around in your sys­tem.

As for se­vere calorie re­stric­tion, the jury is still out. I don’t put too much stock in the left side of the J-shaped curves com­par­ing body weight to mor­tal­ity. Surely a lot of un­der­weight peo­ple have se­ri­ous la­tent health prob­lems. What’s more in­ter­est­ing to me is that the curves flat­ten out be­tween BMI of about 19 and 23.5. This sug­gests to me that one can re­al­ize most of the benefits of re­duced body mass by be­ing nor­mal weight and that af­ter that, if there are any benefits, it’s diminish­ing re­turns.

III. My Ap­proach to Calorie Restriction

I have de­cided to adopt an in­ter­me­di­ate ap­proach to calorie re­stric­tion, i.e. the aim is to stay thin and be to­wards the bot­tom of my metabolic range most of the time. The health benefits to stay­ing thin are pretty clear; there doesn’t seem to be much down­side; and frankly there are a lot of so­cial benefits. The benefits of stay­ing to­wards the bot­tom of my metabolic range are more iffy, but again there doesn’t seem to be much down­side to it. (Put­ting aside is­sues of health, the main down­side is that it hap­pens pretty fre­quently that I will have a meal and eat less food than I would have liked to eat.)

Se­vere calorie re­stric­tion seems too spec­u­la­tive to me to be worth the trou­ble. Par­tic­u­larly given the so­cial costs and the likely diminish­ing re­turns prob­lem. I like hav­ing a some­what mus­cu­lar ap­pear­ance as op­posed to a gaunt ap­pear­ance. Since my main pri­or­ity is to avoid re­grets, I am not will­ing to go this route with­out pretty solid ev­i­dence of benefit.

IIIa. The Nuts and Bolts

What I do is this: I have a ba­sic daily diet which I be­lieve is rea­son­ably healthy and well-bal­anced. Although it is some­what flex­ible, it con­tains roughly the same pro­por­tions of macro-nu­tri­ents and is roughly the same amount of calories each day. From care­ful ob­ser­va­tion, I have de­ter­mined that my ba­sic daily diet is about 500 to 600 calories short of my ac­tual daily caloric needs. i.e. if I stuck to my ba­sic daily diet and ate noth­ing more, I would lose about a pound a week. I add a small sup­ple­ment of ex­tra food to my ba­sic daily diet if I work out at the gym in or­der to bal­ance out the ex­er­cise. (In­ter­est­ingly, I once mea­sured and it seems my ba­sic daily diet, in­clud­ing the ex­er­cise sup­ple­ment, is about 2800 calories. This seems pretty high for a man who is thin, slightly be­low av­er­age height, and only slightly mus­cu­lar in build. I’m not sure what to make of it.)

I weigh my­self ev­ery morn­ing and calcu­late a 7-day mov­ing av­er­age of my weight. I then sub­tract this num­ber from a pre-de­ter­mined refer­ence weight and mul­ti­ply the re­sult by 100. This is the num­ber of ad­di­tional calories I con­sume that day in the form of rea­son­ably healthy foods. The idea is to eat close to the min­i­mum to main­tain weight, thus stay­ing thin and to­wards the bot­tom of my metabolic range.

Now and then my weight spikes up­ward when I have an event which in­volves a lot of eat­ing; af­ter that it drifts back down again. I’ve been calorie-re­stricted in this way for some time now. I feel perfectly fine but af­ter ev­ery meal I feel like I could eas­ily eat more. I pretty much never get heart­burn any­more. I usu­ally wake up quite hun­gry. Th­ese are about the only effects I have no­ticed.

IV. Self-Crit­i­cisms of My Approach

In the in­ter­est of ra­tio­nal­ity, it prob­a­bly makes sense to offer some self-crit­i­cism:

1. I found the above sci­en­tific refer­ences only af­ter I had set­tled on my ap­proach to calorie re­stric­tion. So there is prob­a­bly a cer­tain back­ward­ness about my rea­son­ing. My con­clu­sion is based more on my own in­tu­ition, rea­son­ing, ob­ser­va­tions and com­mon sense than on sci­en­tific re­search.

2. It never oc­curred to me to reg­u­larly mea­sure my body tem­per­a­ture be­fore and af­ter start­ing this pro­gram. Which is un­for­tu­nate be­cause it may have given me some use­ful in­for­ma­tion about the effects of my diet on my metabolism.

3. There’s re­ally no way to mea­sure if any of this is hav­ing an effect on my rate of ag­ing. Without this sort of feed­back, I’m pretty much shoot­ing in the dark.

V. Conclusion

So that’s about the ex­tent of my self-ex­per­i­ment. It’s a bit fright­en­ing that I’m putting my own health on the line in the face of so much un­cer­tainty. At same time, it seems like a rea­son­able, con­ser­va­tive ap­proach which is un­likely to lead to re­grets. Of course there is an ex­cel­lent chance I will never know how much of an im­pact my lifestyle had on my over­all health.

Any­way, I wel­come any in­tel­li­gent thoughts, sug­ges­tions, con­struc­tive crit­i­cism, etc.