Wait, do I only burn 2,938kcal?!

A mystery, wrapped in an enigma..

If you recall, I recently posted very excitedly about doing the Doubly Labeled Water (DLW) test from Calorify, and apparently burning 4,645kcal/day despite being very sedentary.

Backstory: burning 4,645kcal/day?

Both the guys at Calorify and me and everybody else was very confused / skeptical. After all, this is the TEE (Total Energy Expenditure) you would expect from an extreme endurance athlete, not a programmer who’s idea of exercise is walking to the fridge to get more cold brew coffee.

The Calorify test included a phone call with them, and they said that they couldn’t detect anything unreasonable per se about my test. Apparently there have been tests that were clearly off, and gave completely out of scope numbers. E.g. people burning negative calories, or having a negative body fat percentage. These indicate that the sample has been tainted, or something went wrong in the test procedure.

But my sample had none of those signs; it simply had an unexpectedly high TEE number.

What I would have expected would be about 3,215kcal/day, which would be the expected average for my lean mass of about 150lbs. Of course I had been hoping for higher, cause of the whole “low protein increases your metabolic rate” thing.

But 4,600 seemed unreasonably high. If that was true, how was I not losing 3lbs a week? I tracked my intake during that experiment, and it was 2,859kcal/day across the week. And I was roughly weight stable around the time, not just during the experiment week, but the weeks before & after that.

Now the calories on nutrition labels can be off by up to 20% in either direction, and maybe I missed something, or didn’t weigh everything perfectly. Or maybe the fat levels in my cream differed from the label. Or something.

But 4,645 is 60% higher than 2,859. It’s 48% higher than the “expected” value of 3,215. That’s such a massive difference it would make the test completely useless.

Graciously, Calorify offered me a free retest! Thanks, Calorify.

I will say, their service & support is excellent. I suppose that’s what you would expect at $1,000 a pop :) But I really enjoyed it and appreciate how they’re clearly into what they’re doing, it’s not just “a job.” The guy I talked to on the phone had excellent knowledge of the whole DLW and nutrition landscape.

Their test results also come in about 1-2 days after you drop the sample in the mail, not the 2-3 weeks it takes OmegaQuant.

They recommended I wait at least a month before retesting. The test relies on increasing your body water levels of deuterium and O3 to supranatural levels, and they wanted to ensure my levels had stabilized back down to normal levels before testing again.

The retest: 2,938kcal/day

So imagine my surprise when the retest came back as what I’d call kinda low, at 2,938kcal/day. That’s 8% lower than the expected number. Not nearly as far off as 48% high, but…

It doesn’t actually fit my macros this time. If I’d eaten the 2,859kcal/day again this time, sure, perfect match.

But I had been doing ex150 then, and ex115 this time, which is even lower in protein. And on ex115, I noticed eating somewhat significantly more cream, more than making up for the lower carolies from the smaller lunch meal.

I measured my calories again, and this time I averaged 3531kcal/day.

But if I was on a surplus of 600kcal/day, how did I lose 3lbs during ex115? In fact, the 3lbs loss happened just a few days before I began the test.

This doesn’t seem quite as off as a TEE 48% higher than expected, but it also certainly didn’t meet my expectation. Clearly I was eating significantly more in terms of energy, and I had just lost 3lbs (that have stayed off, too, so not just a water weight/dehydration thing), despite allegedly being in a 600kcal/day surplus..

The confusing thing is, this doesn’t even make sense in the “CICO is an accounting tautology” sense. If CICO was even measuring CI vs. CO, it still should be the opposite here. I should be eating 2,890kcal and burning 3,500kcal, and that’s how I lost the 3lbs.

TEE is probably not what people think it is

I suspect that the TEE is just way more variable than people typically assume.

I’ve been doing monthly DEXAs for over a year now, and if it’s shown me anything, it’s that DEXA can be extremely noisy. I can easily gain 4.4lbs “lean mass” in 24h by upping my protein intake. That’s not even eating any carbs, which would bind even more water, or the insane 15lbs I gained in 1 day eating a ton of non-caloric salad. Pro tip: non-caloric salad is almost entirely lean mass.

The TEE is probably the same way. Right now, DLW is the only way to test it as a consumer at all. The only method considered more accurate is a metabolic chamber, but those can’t capture exercise or other lifestyle expenditures, cause you are, well, locked in a chamber.

It also probably costs hundreds of thousands of dollars and you can only do it for a few days at a time, since only advanced research labs at universities specializing in this sort of stuff even have them.

Still, DLW is $800-1,000 at Calorify right now, not exactly a steal.

So since these tests are very difficult & expensive to do, we don’t do them every month.

I bet that our TEE would fluctuate pretty dramatically, week to week, if we could test it more regularly. I hope the cost comes down over the next couple of years as companies like Calorify grow & bring this technology to consumers.

A swing up to 4,600kcal would be extreme, but who knows. I’d definitely expect 10-20% swings in either direction, even if you did nothing. With severe caloric restriction, weight loss, or severe overeating, probably more.

Maybe my TEE was in a low-swing because I’d just lost 3lbs? Maybe it’s just noise?

The circumstances around this retest seem to disprove either the retest, or CICO, once again, lol. If I lose weight, my CO should be higher than my CI. That should be true both if CICO is causal in the fat loss, or if it’s just an accounting measure (as I believe).

Other differences: body comp

The TEE is the main thing you get from a DLW test, but, interestingly, it is also a very precise way to measure your body fat %. Because fat is not very metabolically active, whereas lean tissue is, they can determine how much fat you have on you.

This is what they told me last time:

Interestingly, I was almost the identical total weight this time, over a month later, at 219.9 vs. 219.5lbs.

According to DLW I gained 4.6lbs of fat free mass, and lost 4.2lbs of fat. My body fat percentage is 2% lower, the lowest I’ve ever measured at 27.9%. Yay!

My hydration was a tiny bit higher, but very close. Somebody recently asked my how much water I drink in a day. I suppose the answer is 7 liters, which is just under 2 gallons.

So, uhhhh…

I guess this doesn’t tell us much. The 4,600kcal/day measurement might have been a testing error, or a pretty extreme fluke during that week.

At the same time, this number doesn’t make any sense either given the circumstances.

Overall, I’m very suspect of all these methods of measuring CO, be it DLW or metabolic chambers. Like IQ tests, if you can’t actually repeat the test (due to cost in this case), I’m very skeptical of your results.

It might be that these are only accurate to some percentage. Or it might be that, like DEXA, they’re pretty accurate, but you’re measuring something that just naturally has a ton of fluctuation.

Another point is: the value they get isn’t an actual TEE, it’s a ratio. They then have to apply math including assumptions about the macros you’ve eaten during that time.

That’s fine with somebody like me, who eats the same meal every day and can accurate macros very accurately.

But if you are giving a DLW test to a Hadza hunter-gatherer on the plains of Tanzania, how accurate are your macro estimates going to be? Even if you ask him how many nuts vs. meat vs. honey vs. tubers he’s eaten that week, is he keeping a food log? And won’t the macros on those natural, wild foods be off way more than the 20% on nutrition labels allowed by the FDA?

These would significantly influence the calculated TEE.

Maybe all these factors explain the “surprising” 700kcal swings in either direction observed by Pontzer et al for people with the same lean mass & activity levels.

Should you do the Calorify DLW test? I’d say, probably no. Unless you’re a bored nerd like me with money burning a hole in your pocket, it’s probably not going to be of much use.

In fact, the only real use I see for measuring your CO is to rule out that your metabolism is severely depressed, and indirect CO2 calorimetry to measure your RMR is just as good for that, I think. The RMR is the majority of your TEE anyway, 2/3 or more.

If you have a history of severe undereating or caloric restriction & dieting, and you suspect your metabolism is severely down-regulated, get an RMR test done for typically <$100. Many fitness or lab places offer these, even some gyms. It’s 1/10th the price of DLW, it’s widely available in most big cities, it takes 15 minutes of breathing into a tube instead of a week’s worth and collecting & mailing in your urine.. and it tells you all you need to know.

I’ve actually had a few readers do this after they told me about their potentially lowered metabolism, and one guy’s test came back absurdly low, like 1/2 of what it should be. He tested again, and it was nearly as bad.

So it does seem that an RMR can actually detect a severely down-regulated metabolism. That is a good thing to know about your metabolism, and a good thing to rule out, too.

I therefore highly encourage worried dieters to do the <$100 RMR at least once. But until the DLW comes down in price to maybe $200-500, I don’t think it’s a great value for most people.