Rapid Weight Loss Tanks Metabolism? The TBL Study

Thanks to Yoni Freedhoff of Weighty Matters blog for providing me with the full text of this one.  Check out his take on the results.  Update 11/11/13:  Full text now available free HERE.
Context: An important goal during weight loss is to maximize fat loss while preserving metabolically active fat-free mass (FFM). Massive weight loss typically results in substantial loss of FFM potentially slowing metabolic rate.
Objective: Our objective was to determine whether a weight loss program consisting of diet restriction and vigorous exercise helped to preserve FFM and maintain resting metabolic rate (RMR).
Participants and Intervention: We measured body composition by dual-energy x-ray absorptiometry, RMR by indirect calorimetry, and total energy expenditure by doubly labeled water at baseline (n = 16), wk 6 (n = 11), and wk 30 (n = 16).
Results: At baseline, participants were severely obese (×± sd; body mass index 49.4 ± 9.4 kg/m2) with 49 ± 5% body fat. At wk 30, more than one third of initial body weight was lost (−38 ± 9%) and consisted of 17 ± 8% from FFM and 83 ± 8% from fat. RMR declined out of proportion to the decrease in body mass, demonstrating a substantial metabolic adaptation (−244 ± 231 and −504 ± 171 kcal/d at wk 6 and 30, respectively, P < 0.01). Energy expenditure attributed to physical activity increased by 10.2 ± 5.1 kcal/kg·d at wk 6 and 6.0 ± 4.1 kcal/kg·d at wk 30 (P < 0.001 vs. zero).
Conclusions: Despite relative preservation of FFM, exercise did not prevent dramatic slowing of resting metabolism out of proportion to weight loss. This metabolic adaptation may persist during weight maintenance and predispose to weight regain unless high levels of physical activity or caloric restriction are maintained.

Now, the results in the abstract sound daunting and a lot of people point to the techniques used on The Biggest Loser to blame the relapse of a good number of contestants.  In a 2010 podcast with Jimmy Moore, Dr. Michael Dansinger who works on TBL  gave some unscientific stats that roughly 1/3rd kept the weight off, 1/3rd gained back significant amounts -- like half, and 1/3rd relapsed to starting weight (or higher?).  Even if these are a bit "off" this is no worse and likely better than the general population track record, and that includes all the millions who have shed buku poundage on Atkins, etc.   More thoughts on that later.  So they took 16 participants and "linear regression analysis was used to generate an equation for predicting RMR based on FFM, FM, age, and sex at baseline".  Here is the plot of adjusted RMR's and the equation for the regression line used to predict RMR at reduced weight and the table of results:

Now the first thing that stuck out to me was the amazing RMR's!!  I mean at Week 30, at ~ 190 lbs average weight and 27% body fat, the average RMR was 1763 cal/day.  I know without having it checked that my own RMR at ~200 lbs (I logged intake and weighed for a pretty decent stretch in 2009) had to be quite a bit lower as I maintained at roughly 1500 cal/day.   As if 1763 weren't enough, their TDEE was 2900 cal/day -- an enormous amount of food!  I'd say that it's really hard to justify any sort of assertion that TBL "damages" let alone "destroys" contestants' metabolisms.  Now I imagine the TDEE maintenance calories would go down w/o the 4-6 hrs/day of exercise, but if one picks the right foods, the 1763 cal/day RMR translates to roughly 2350 cal/day for a very sedentary person (using RMR as 75% of TDEE).  When one considers that Mark Sisson's full sample menu (which he states he rarely eats in its entirety) is around 2500 cal/day, I think making excuses for regain based on some differential from predicted reduction in RMR is bogus.  That's two 1000 cal meals and a 500 cal meal.  If one of those 1000 cal meals is breakfast, that's 5 eggs fried in butter and a large bagel with cream cheese.  Then one could go to McD's for a light lunch for 500 calories and eat 3 Lean Cuisines for dinner.  I mean really ....

Frankly as I've been working on my RMR post, I must say I was shocked to see how high their RMR's were.  Their initial RMR's are also phenomenal so it's fair to say these contestants did not get obese because their metabolisms were hopelessly slow or they had dysfunctional mitochondria or whatever.

So, is there any other useful information to be gleaned from this study and/or TBL in general?  Well, for one, overtraining -- and I don't subscribe to this part, but it IS a competition reality show after all -- and whatever cortisol that produces does not prevent *massive* weight loss.  Secondly, from the use it or lose it category, high volume exercise -- the bulk of which is "cardio" -- does appear to be quite effective in maintaining lean body mass.   Now, here's my rub with how this study was presented.  They say:
Despite relative preservation of FFM, exercise did not prevent dramatic slowing of resting metabolism out of proportion to weight loss.
And yet the plot was for adjusted RMR and then the regression line used to predict the post-weight loss intervention took other factors into account.  Yet RMR is know to correlate rather tightly with FFM (fat-free mass aka LBM = lean body mass).  I would love to have seen a regression of measured RMR vs. FFM.  Perhaps this would produce the same conclusions, but body weight does NOT correlate all that well with RMR.  If you're looking at how an intervention impacts metabolism, and you're going to "call out" preservation of lean mass, it would be more appropriate to present that analysis (if it was even done, and if not, why not?) than the analysis they did.

The results of this study demonstrate that despite a relative "tanking" of metabolism, participants were able to shed boatloads of fat with admirable preservation of lean mass.  That perhaps the rapidity of the intervention is  insufficient to allow for adjusting to the NORMAL food intake required to maintain the losses.


bentleyj74 said…
Yep, learning how to eat to lose weight is completely different from learning how to eat to maintain. The new normal so to speak. TBL contestants learn how to endure boot camp style weight loss not how to structure their own real lives with all the variables in play to support their goals and having that be "normal". I really think the metabolic stuff is a lot of hand waving.
Gys de Jongh said…
Seen this ?

Obesity (Silver Spring). 2012 Feb 13. doi: 10.1038/oby.2012.34.

Greater Than Predicted Decrease in Resting Energy Expenditure and Weight Loss: Results From a Systematic Review.

Changes in resting energy expenditure (EE) during weight loss are said to be greater than what can be expected from changes of body mass, i.e., fat mass (FM) and fat-free mass (FFM) but controversy persists. The primary focus of this study was to investigate whether there is a greater than predicted decrease in resting EE during weight loss in a large sample size through a systematic review.

This analysis does not support the notion of a greater than predicted decrease in resting EE after weight loss.

PMID: 22327054
fredd said…
Being a strong advocate of resistance training, I would say that with a loss of ~10kg of lean mass, "Despite relative preservation of FFM" is a bit of a stretch. I would love to see a similarly well controlled study that incorporated resistance training rather than purely cardio (which when combined with calorie deficits, is known for muscle catabolism).
Sanjeev said…
except that when one puts on fat mass, unless the diet is EXTREMELY bad, 30% of the weight is lean mass(number courtesy Lyle McDonald), even in the absence of any training. While much of that is probably connective tissue, skin, bone and water (hydrated adipocytes?) a bunch is muscle too.

I forget where I read it but I agree with the observation ... everyone complains about the metabolic "downside" of losing weight and forgets that when they gained, their metabolic rate was probably higher than if they had remained at steady weight.
fredd said…
"except that when one puts on fat mass,"

Sorry, I don't know what you are trying to say?

It is a lot easier to hold on to lean mass (and hence retain a higher metabolic rate) with resistance training when losing weight, than it is to gain lean mass - that is what I was saying.
Sonnenschein said…
Sanjeev, did I get it right? When a person gaines 10 kg of scale weight 3.3 kg of it are lean mass even when the individual is totally sedentary? Does it apply to both men and women? I could imagine the the hormonal invironment in women would rather promote more fat gain. I think that would make sense...
Sanjeev said…
(answering fredd and you here) ... I wasn't claiming any of fredd's points were INcorrect; one does lose lean mass with adipose losses. My point was just that from another angle, elements of the story can be viewed as a "good deal".

> gaines 10 kg of scale weight 3.3 kg of it are
> lean mass even when the individual is totally sedentary

yes, the amount of lean mass one gains along with adipose gains is individual - natural testosterone variation and age probably accounting for huge part of the variation. The 30% number is obviously an average. I dont recall the error bars or standard deviation numbers.

I don't know if this applies to the hyper-obese. I would suspect there's a definite levelling off of lean gains above some threshold.
CarbSane said…
The Bray overfeeding study showed that overeating on a high protein diet leads to greater weight gain due almost entirely to adding more lean mass ALONG with the fat mass. At some point I think the proportion of fat mass has got to increase, especially as someone gets more sedentary, but we always gain and lose both.

@fredd: I think when losing close to 60 kg, roughly 10 kg LBM loss would be considered quite good. I have seen total retention of LBM only in studies that involved far smaller losses in total mass. I'm not sure you want to retain all of your LBM even if it means a lower metabolic rate. In my case, I think I may need to deliberately lose lean mass as my appetite (for protein) seems quite well dialed to my current level of LBM. Although I have fat mass left to lose for sure, I think I retained too much lean ... dunno if that makes any sense at all. While metabolic rate correlates highly with LBM it does not appear to be consistently true within the individual. It's been shown that calorie restriction makes our bodies more efficient.
Sonnenschein said…
Evelyn, as to your last point (calorie restriction making the body more efficient): I thought that this was one of the diet myths (you know, the broken metabolism thing that only the Paleo-diet might cure). I am asking because I wonder how exactly the body becomes more efficient. The necessary metabolic prossesses (digestion, heat regulation etc.) must function just as well while requiring less calories? Or does the thyroid function go down?
CarbSane said…
I think the adaptation is more "fact" than myth. Eat less and weigh less and you will burn less. Starve yourself and the body does go into starvation mode where basal metabolic rate drops (you might feel colder) but oddly enough we burn fewer calories during activity. This may well be because energy expenditure measured during, say, walking includes resting so if you usually expend 50 cal/hr to sit on your butt and burn 100 cal/hr moving around a bit but now burn only 90 cal/hr doing the same movement it could be b/c your RMR is now only 40 cal/hr. I'll have more on this sometime next week when I finish up the metabolism post.
ProudDaddy said…
Evelyn, tsk, tsk! You sound like a teenager who is never going to get old. Or maybe you really didn't mean you have too much LBM? If you did, perhaps you should start practicing the shuffle-walk of the frail -- you can see it everywhere. Please don't suggest to people that sarcopenia, under any circumstances, is a good thing.
CarbSane said…
PDaddy, I'm not old, but hormonally I'm even older than my years being postmenopausal for 2 years now but not yet 50. The reason I go on at times about my size is that anyone can go to Kohls or Sears or JC Penney and pick up a pair of size 10 Lees and that's what fit me comfortably at 200-215 lbs. They get a bit snugly at 215, but that is a weight I saw on my scale where my jeans fit. Now contrast that to Carnie at 218 on the Oz appearance. She's likely a 20 or higher. People pack weight differently. I think I conserved an awful lot of lean mass. I've always been muscular, but I also had my bone density checked once at a screening. Leaving aside that it may not be the most accurate test, my density was almost 3 standard deviations above average for a 30 year old woman. My bones are super dense and that is also included in LBM, and I found some disturbing information about too-dense bones when I got those results. For me, sarcopenia is not a concern, yet. For me, losing LBM will not get me sarcopenic in any way, shape or form. I was not suggesting to people that sarcopenia is a good thing. I am suggesting that loss of LBM when one has been significantly overweight is not necessarily a bad thing. I stand by that. :)
RRX said…
Dude. They lost an average of 137 lbs of weight, with only an average of it being 25 lbs of lean body mass. I think that DOES line up with the quote, "Despite relative preservation of FFM"
RRX said…
I can say from experience, don't worry. If you're not pump 'n toning those legs, the lean mass will slowly come off with time.
RRX said…
Greetings Evelyn,

It has been a while since I've commented on here. I've been busy, but I check out the posts from time to time. I could not resist commenting on this one though. It relates too much.

For a refresher: In 2000 I was 300 lbs. By 2004 I was ~180 lbs. I maintained around there until the end of 2010. All that was done low/no carb. Through Carbsane, another site, and my use of university journal access, I learned what the research actually says about kcals. So at the end of 2010 I threw out low carb. The result was a quick drop to 165 lbs. I maintained that through all of 2011. At one point I used the usual practice in research of tracking my kcals with a slow weekly increase to find my avg TDEE to be ~2650 kcals. Knowing what I knew and being so close, I chose to put this knowledge to use at the beginning of of this year to finally lean out to the extent that I always wanted. That resulted in reaching ~10% body fat last month at 150 lbs. As a former low/no carber that maintained for years between 180-190 lbs with a body composition I did not like, my experiences since the end of 2010 have been LIBERATING and transforming. I had given up on this scenario for myself for many years.

With that in mind, my maintenance has been ~2500 kcals/day (and by that I mean average. I eat based on hunger and life with some days high and some low) at this new weight. I also had my RMR measured twice at this new weight and body comp. They produced an RMR of ~1450 kcals/day. Because of all of this, I cannot side with any lamenting over the supposed lower than expected measures for these subjects. Both my RMR and my TDEE are lower than the average of these subjects and I STILL reached my desired composition (weight I ended up at was a byproduct, as it was the composition I was after). I think the researchers said it best: "Although metabolic adaptation acts to decrease the rate of weight loss, it was the subjects with the greatest weight loss who had the greatest metabolic adaptation." A lower than expected metabolic rate does not mean anyone HAS to stay heavier than they want to be. I sure hope people don't use this study as an excuse to not bother trying.

As for the RMR numbers, I have seen plenty of former obese subjects in multiple studies with RMRs like mine that are lower than the subjects in this study. In fact, the only time I see higher RMRs are with never obese subjects. It's not pleasant, for sure, but I think we're just handicapping ourselves if we try to think/live like a never obese person. I have a lower metabolic rate than another 150 lb 5'9" male that has never been obese. OK. I'm not going to bitch about that while I consume more energy than I expend. That's just ridiculous.
RRX said…
I like that you pointed out that the subjects could not use the low metabolism as a reason for becoming obese. Their average starting TDEE and RMR was plenty high. As well, the researchers said their triaclglycerol levels were normal at baseline and, "The RQ was low at baseline, suggesting increased fat oxidation at rest, and did not change from baseline to either time point." So...you mean they didn't get obese from a messed up fat metabolism? Their fat wasn't locked away in fat cells unavailable to them to use for energy? You mean their bodies were using fat for energy? But, low/no carb dogma says otherwise!

I also like that you pointed out that "over-training" and the supposed high cortisol levels did not seem to stop these subjects from losing weight. That is something that I have realized over the last year from reading actual weight loss research. The popular media and gym culture LOVES to talk about those two things...but they never seem to show up in the research as something that matters for moving the scale when an actual deficit is in place... And the cardio didn't cause them to lose all their muscle was a nice catch, too. I hear/read that myth all the damn time.
CarbSane said…
Hi there! It's great to see you here! CONGRATS on the awesome progress. Per your comment below, this study pretty much blows lots of excuses right outta the water, eh?

Hope all's going well with the studies :D
PhilT said…
What was the intervention - the abstract looks like is missed the proof reader - what did these folks eat ?