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July 15, 2007
A Pretty Common Misconception About CR
Oddly enough, it's a pretty common misconception about CR that CR means being in perpetual negative energy balance. Certainly, this is true during the initial phases, which result in weight loss. However (and this is why I preface with "oddly enough") if you were to continue to be in negative energy balance, eventually you would die. Literally waste away to nothing. That's no fun.
Another common misconception about CR is that it lowers your metabolic rate. It does, in the initial phases, just like any weight loss diet would. But over time, the specific metabolic rate (which means the metabolic rate per unit of metabolically active tissue) returns to normal when you find a sustainable energy balance (at your new lower weight) where you are no longer losing weight. Of course, the smaller, lighter person will require fewer total calories to be in energy balance than he or she did pre-CR. Fewer total calories. But, that doesn't mean that he or she is in constant energy deficit, or that his or her metabolic rate is actually slower. (This is the distinction between "basal" and "specific" metabolic rate ). MR had a period of strange weight loss, while he was eating exactly (and I mean exactly) the same number of calories when his metabolic rate jumped back up after the initial (fairly long, as he lost weight slowly like a sensible person) weight loss phase. During this time, he wasn't eating any less or being any more active, but he lost a little weight. His metabolic rate is now much more steady. That was years ago, of course.
Most people never really notice things like that since they don't carefully weigh and measure their food.
I don't buy Tony's "CR Calculator" because a) it's impossible to come up with a generic "control twin" for a human b) his "% CR" tells you what energy deficit you would have relative to a person of a given BMI (the "control twin".) It calculates total energy deficit (relative, again, to an arbitrarily-selected BMI), not degree of calorie restriction, and part of that energy deficit calculation is exercise which has nothing to do with degree of CR.
MR's "control twin" on Tony's calculator weighs more than the real MR ever weighed, eating ad lib (and that was a diet full of pizza parties and mac and cheese.) My "control twin" weighs 120, which was a weight at which I was moderately overweight, and eating a diet that I don't even want to think about now. Sure, I fit in on the height weight charts. But people vary, a lot.
What people do not do, however, is defy the laws of thermodynamics. Those who remain in constant energy deficit will lose weight. Did you ever see that weight loss calculator which tell you, in rather big letters, that at this rate of energy deficit, you will weigh NOTHING in x number of months and days? That's not the object of the game.
The final problem I have with Tony's "CR Calculator" is that it asks folks how many calories they eat. Very, very few people really, really know. Because they don't weigh and measure and they eat out a lot. That's fine, you can restrict yourself to somewhat (a few) fewer overall calories than you had before without knowing exactly precisely how many fewer. But a device that relies on people to accurately report their calorie intake is only going to work for about ten people who actually know how many calories they are eating for sure. I suspect that I can name those ten people. They are very nice.
Because the people who read my blog are in large part very nice as well, and I don't want them to pull a Julian Dibbell and eat way too few calories with the resulting too fast weight loss and becoming convinced that long term CR is impossible, I get rather touchy about impossibly low calorie number reports. I wrote a rather curt letter to Grazia after they misquoted me saying that I eat 1000 calories a day. Sure, I eat 1000 *some* days... but that is balanced off by days when I eat much more. If I ate 1000 calories a day, I would rapidly cease to exist, and that would cause great inconvenience to my cats. Since I can not bear the thought of inconveniencing a cat, I try to eat in a way that is responsible to my health. That means eating enough, while trying to eat no more than just enough, and getting the right nutrition. And not fixating on an arbitrary number but constantly readjusting my practice to improve my health and my quality of life.
This isn't a competition to see who can eat the fewest total calories. It's a long long journey into what we hope will be a healthy, vigorous future.
Posted by april at July 15, 2007 5:56 AM
Comments
Thanks for this post April! I totally agree that unless a person is weighing and tracking everything they are eating, they can't know what their calorie level is. I average 1200 calories a day during the week, but on weekends I do not always weigh/track everything I'm eating, or I'm eating out, resulting in much higher calorie days. To say I eat 1300 calories per day would be inaccurate - more like 1300 calories per day that I'm tracking carefully! This would explain why at 5'8 I am not wasting away :)
You've reminded me that I need to be more consistent with my weighing/recording to truly know my average calorie level. Now I'm curious to see just how many calories I am honestly averaging so I'm going to try to be one of those ten people for a while.
Posted by: Zana at July 15, 2007 1:55 PM
Great post April. You've outlined some really important points here. I often think that people reading the CR blogs can get the wrong impression because it is often just a look at a single isolated day and not the entire dietary picture.
Like you I often keep the calories lower during the week to allow for a bit of indulgence on the weekends, but I don't always talk about those higher calorie days on my blog.
I am one of those smaller people, but even I wouldn't do so well if I maintained a 1000 calorie average for too long, although this is often my weekday average.
You are right - health must be our major focus -and if that means adjusting calories to suit the current life circumstances then that is what we have to do.
Posted by: Mizpah at July 16, 2007 3:30 AM
I think your post makes a lot of sense.
Is it possible that if someone is not eating enough calories, that the body might stop metabolizing? For example, if someone did not eat enough calories, her body might cling to every morsel of nutrition and instead of burning it to lose weight, the body stored it to maintain?
I think this is all fascinating! I hope it's ok that I'm here, even though I weigh a lot more than most on your site...
Posted by: Serena at July 16, 2007 11:47 AM
hi, April
I have a couple of bathroom scales and weigh myself every morning -- which is a lot easier than weighing food and calculating calories. as long as I am losing weight slowly i am on the right track.
the problem with counting calories is that you have to count how many calories you consume and how many calories you spend in physical activity and because each day requires different activities and calorie expenditure one can lose weight too fast -- which isn't healthy in the long term.
Posted by: nick at July 16, 2007 12:18 PM
April,
as I start actually weighing and tracking my food, I'm amazed/appalled at how much I'd been eating. Yeah, I've counted calories before, but it's been a wishful thinking type of estimation for the most part. I also like your point of there being no such thing as a control twin--for better or worse I carry my weight pretty well and consistently look about 20 pounds less than I really am. unfortunately, that allowed some bad habits to creep in.
Nick--I'm glad that strategy works for you, but I think it helps to be male. :-) There are certain times of the month when I've been known to gain 5 pounds of water weight in a manner of hours...the only time I've been able to successfully restrict my calories is by (accurately) counting my calories.
Posted by: Sarah at July 16, 2007 7:11 PM
Nick, you might be losing weight slowly, which is good, but without tracking your food, how can you know if you're getting good nutrition? You'd probably be all right if you're following The Zone or South Beach but just basing things on weight loss is (IMO) not a good idea for long-term health. JD
Posted by: Judith at July 16, 2007 7:44 PM
Yes, don't inconvenience your cat! I love the explanation of basal vs. specific metabolic needs, especially since my boss is always ranting about people who try to defy the laws of physics in their diets, driving, or whatever. I haven't looked at Tony's calculator, it sounded pretty silly to me. I also keep the "energy balance" in mind every day, since it's part of the foundation for my CR.
Emi (and Leilu)
Posted by: Emi at July 17, 2007 1:06 PM
Are you sure about that theory?
My recollection is that there is evidence that under strict CR the cells of the body use different metabolic pathways to derive energy or to utilize energy, and thereby perhaps derive energy or utilize energy more efficiently.
If that is the case, then the "metabolic rate per unit of metabolically active tissue" may actually decrease with strict CR, without violating thermodynamic laws.
If you look at the chart shown here: http://calorierestriction.org/ there are a few relevant observations to consider ...
1.) The mice on 65% calorie restriction live the longest. Are you saying that they must be only 35% of the body mass of the control? (i.e. Have only 35% of the "metabolically active tissue" ... since they only receive 35% of the calories of the controls?) If your theory is correct, then that would appear to have to be the case, especially since the highly CR'd mice evidence high activity rates comparable to the controls.
2.) Many people have a normal metabolic "burn" rates of about 2000 calories a day. Are you saying that although mice can *thrive* at a 65% calorie restriction, that humans cannot even *survive* at a more moderate calorie restriction of 50% = 1000 calories per day? Is 50% calorie reduction really impossible for humans to maintain? What then is a practical limit of CR for someone with a normal metabolic burn rate of about 2000 calories per day?
btw: Make that 11 people. I know virtually exactly what I have eaten for over 2 years now. For instance, over the past 2 years, my metabolic "burn" rate calculates out to be about 2064 calories per day; and my calorie intake has averaged almost *exactly* 1974 calories per day (known from meticulous record keeping, and exacting detail, assisted by the fitday.com nutrition program) ... and those numbers are constant with the twenty pound weight loss which occurred over that period of time. Due to deviations from plan, my caloric intake has varied substantially over different months-long periods. My goal is to radically lower my calorie consumption on a sustained basis ... I'm slowly getting there!
ps: Alcohol daily average = 10g = 68 cals = 3% total calories ... however, many multi-month periods of no alcohol consumption. High sigma (Std Dev) on the frequency distribution curve! ... :>) ... yah, I like it like that!
I am very curious about what the minimum caloric intake level is which will maintain me at about 5% to 7% body fat ... for me, that will be the limiting factor for what will be the lowest level of daily calories I consume. Does that make sense? ... to have that as a limiting factor?
Posted by: CRWilliam at August 15, 2007 12:51 AM