The consensus seems to be that if you’re fat then you eat more calories than you burn. That’s not quite a revelation is it? It’s kind of like saying that a room is crowded because there are too many people in it. While essentially correct, it doesn’t really provide any useful information.
The Very Scientific People, or VSP (not to be confused with Krugman’s VSP, which are Very Serious People…) would have you believe that to lose one pound of body fat in one week you have to have a daily caloric deficit of 500 kilocalories.
Well, at least we know the VSP can accomplish third grade math, 3500 Kcal for a pound of fat, divided by 7 days in a week, gives you 500 Kcal per day.
But here’s the rub, how do you measure the calories ingested, or those expended for that matter?
I recently read the article The Math and thought it would be a good example of following or trying to follow the VSP method of weight loss. Now I’m not picking on the Wankmeister, really, and not just because he’s a lawyer and would sue my pants off, but he put the data out there, so I’m going to use it.
In the article, Wanky details his food intake for the day, as well as his riding/exercise/output/calorie burn, to wit:
‘…BMR 1,800 cal burned
Swami’s Beatdown and Bonus Ride 2,873 cal burned
Walking slowly around San Diego for 1.5 hours 200 cal burned
Calories out: 4,873
Calories in: 4,320…’
First off, the thought that Wanky is eating 4000+ calories and still losing weight at 150 pounds, plus or minus a couple, I find rather depressing. I eat barely more than half that daily and still battle constantly. If I ate that much carbohydrate, let alone the total calories, I’d gain 5 pounds just from that one day.
The big question is did he really eat all that? Now, I’m not suggesting that Wanky is dishonest, but even if his measuring and weighing were perfect, the known calorie content is certainly less so.
‘The FDA allows manufacturers and packagers a surprisingly wide margin of error–the information can be off by 20% in either direction and still be in compliance.’ – Can you trust the nutrition facts?
So if we look at what Wanky ate, the possible 20% error means that what he calculated to be 4320 Calories may have actually been as low as 3456, or as high as 5184, and that doesn’t take into consideration any errors in weights and measures.
Please don’t take this to mean that I don’t think you should count calories. Lord knows I count them, and do everything in my power to make my counting as accurate as possible. No, all I’m trying to illustrate is that while the VSP may have their arithmetic right, the inherent error in the caloric content data is sufficient to obfuscate any possible deficit.
Since that’s clear as mud, lets look at the output side…
BMR is supposed to be the amount of energy you burn just being alive. You can have your BMR measured in a lab, but it’s kind of a snap shot sort of thing because there is quite a bit of variance day to day, so even if measured ‘scientifically’ it’s more of an estimate from then on.
‘Basal metabolism is usually by far the largest component of total caloric expenditure. However, the Harris-Benedict equations are only approximate and variation in BMR (reflecting varying body composition), in physical activity levels, and in energy expended in thermogenesis make it difficult to estimate the dietary consumption any particular individual needs in order to maintain body weight.’ – Basal metabolic rate
Most people don’t have their BMR measured regularly in a lab, most just use the Harris-Benedict equations mentioned, well, no, most people just use a BMR calculator.
OK, so BMR is an estimate, but how good is the estimate?
I haven’t a clue…
Well, at least we can depend on Wanky’s high zoot, über expensive power meter to give us reliable data from his ride. Provided his power meter is up to snuff, the manufacturer says it’s accurate to ± 2% (best case scenario, depending on manufacturer), so that 2873 Calorie Swami beat down may have been as low as 2816, or as high as 2930.
But wait, it gets better…
As I’m certain you’re well aware, a power meter bases its data on strain gages (the more popular ones anyway), which in turn is constructed into a torque value, which measured over a time interval gives you a power measurement.
That power measurement is converted from kilojoules to kilocalories by way of a standard conversion factor, wherein:
1 kilojoule = 0.239005736 kilocalories
If you were to divide 1 by that 0.23900576 factor you’d get 4.184, or at least that’s what my HP scientific calculator tells me.
So what? Well, it’s common practice to use the total power reading as the Calories burned because of that factor of 4.184, since humans are in the range on 20 -25% efficient in converting energy burned into work.
Therein lies the rub; I’m pretty sure Wanky is human, so he could be as low as 20% efficient, or as high as 25% efficient.
To get an idea of the possible range of caloric expenditure let’s look at best and worst case scenarios.
The lowest caloric expenditure would correspond to the reported value of 2873 being 2% high, and the actual expenditure being 2815.54 kilocalories, backing out the ‘standard’ conversion and using the highest efficiency (25%) instead, would put the expenditure at ~2692 Calories.
The high expenditure would correspond to the reported value being 2% low, and the actual expenditure being 2930.46, backing out the ‘standard’ conversion and using the lowest efficiency (20%) instead, would put the expenditure at ~3502 Calories.
That’s a difference of ~810 Calories based on the range of efficiencies generally accepted. I suspect that a person’s actual efficiency could be measured, but I don’t know how accurate the measurement would be, or whether efficiency is constant or variable.
Yes, it is possible to be exact about caloric intake and expenditure, but it requires sophisticated instrumentation in a lab setting, and you pretty much have to live in a sealed bubble for the duration.
Can you say lab rat?
So, shy of becoming a man among mice, what’s a person to do?
Well, like I talked about in Trafalgar and Cycling you do your best to take the fight to the enemy. You track your diet as best you can, you track your training as best you can, you learn, adjust, and you stay the course.
Surrender is not an option…
The purpose in writing this wasn’t to dash your hopes, or illustrate the futility of the exercise, quite the opposite. The whole ‘eat 500 Calories less than you burn’ thing has been bouncing around for what seems an eternity, and is parroted incessantly, by people who really should know better.
It just pisses me off whenever I hear it…
For all the reasons I’ve explained here, and lots that I haven’t, you can do everything right, your sums come where they should, and still not lose weight.
That’s just depressing, frustrating, and it makes all the effort and sacrifice seem pointless…
Everyone is different, everyone’s weight loss is an n=1 experiment, and hopefully I’ve shown that there is enough variance, and error in the ‘data’ that you should feel comfortable experimenting to find what works for you.
Just because ‘they’ say that you should have a 500 Calorie deficit, and they may well be correct, doesn’t mean that you shouldn’t change things around to get the scale to move, regardless of what the numbers come out to on paper.
In the end, the scale is the ultimate arbiter to the efficacy of your program