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Rapid Weight Loss Really Does Release Toxins from Fat

Dean Pomerleau

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The idea that rapid weight loss can result in release of toxins stored (relatively harmlessly) in body fat cells gets bandied about pretty regularly. In fact I've done it myself several times in just the last couple days (here and here). I've never actually looked for evidence to support this conventional wisdom, which has left me with a nagging feeling of dis-ease. I try not to make claims that I can't back up with evidence. So I figured I would look into it and start a new thread to collect the evidence and encourage discussion about it.


Coincidently (or perhaps not?!), Al Pater posted this new study [1] today, which bears directly on the topic. In it, researchers followed 32 women who had just given birth and were breast feeding to see how the level of persistent organic pollutants (POPs) in their breast milk changed as a function of postpartum weight loss. All the women lost at least some weight in the 24 weeks of the study, and sure enough, the amount of POPs in their breast milk was highly correlated with the amount of weight they lost: 


Among these women, the concentration of PCB 153 in HM was significantly (p = 0.04)
higher at follow-up than at baseline. Weight loss was significantly
positively associated with changes in concentrations of all studied POPs
(2.0-2.4% increase per percent weight loss).


Since these women probably weighed in the neighborhood of 140-180 lbs to start with, it appears that the level of toxins in their breast milk went up by about 1-2% per pound of weight loss. Since not all of the toxins released end up in breast milk (especially in men and non-lactating women!) I would expect the increase in toxin load circulating in the blood per pound of weight loss to be higher than that. 


So [1] definitely supports the idea that rapid weight loss increases circulating toxin load.


But even more direct and conclusive evidence of dieting-induced toxin release is study [2]. In [2], researchers followed 45 morbidly obese women for 6 months following either bariatric surgery or intensive dieting. These women were really heavy to start with - average BMI around 40. And they lost quite a bit of weight (-32lbs of body weight on average) in a relatively short period of time (six months). But in fact that translates into 1.23lbs per week of weight loss, which is very close to the maximum rate of weight loss we recommend around here, ~1lb per week.


So what did they find? 


A very large increase in the same Persistent Organic Pollutants (POPs), to the tune of a 50% increase on average:


In patients who lost weight, serum [total POP] levels displayed an increase after 6 months of approximately 50%. ... [T]he increase in [Total POP] serum levels after 6 months of weight loss was more pronounced in patients losing relatively more visceral adipose tissue.


So even the kind of "slow-and-steady" weight loss we recommend of 1lb of weight per week results in a dramatic increase in toxin load that persists for at least six months. And visceral fat loss is a bigger factor contributing to toxin release than subcutaneous (love-handle) fat loss. In satisfying agreement with the 1-2% increase in POPs per pound of weight loss observed in [1], this study found that an average of 32lbs of weight loss resulted in a 50% increase in average serum POP level, which equates to ~1.5% increase in circulating POPs per pound of weight loss.


So in general even 1lb of weight loss per week may be too rapid...


Ah. That feels better. My cognitive dissonance is subsiding... Now I can go back to those two posts and insert a link to this thread. And now we have a place to point next time anyone makes the statement that rapid weight loss releases toxins into the blood.





[1] Chemosphere. 2016 Jun 6;159:96-102. doi: 10.1016/j.chemosphere.2016.05.077.


Environmental organic pollutants in human milk before and after weight loss.


Lignell S, Winkvist A, Bertz F, Rasmussen KM, Glynn A, Aune M, Brekke HK.


Many persistent organic pollutants (POPs) are banned because they accumulate
in organisms and are toxic. Lipophilic POPs are stored in maternal adipose
tissue and concentrations in human milk (HM) may increase during weight
loss. Our aim was to examine associations between weight loss and
concentrations of chlorinated POPs in HM in lactating women participating in
a weight loss study. We analysed POPs (PCB 28, PCB 153, HCB, DDE) in HM at
12 and 24 weeks postpartum from 32 women who participated in a randomized, 2
? 2 factorial trial of diet and exercise for postpartum weight loss.
Participants donated milk before and after the intervention period. We
examined associations between weight loss and change in POP concentrations
and estimated the intake of POPs by their breastfed infants. Most (n = 27)
women lost weight during intervention, 0.45?0.30 kg/week (mean?SD). Among
these women, the concentration of PCB 153 in HM was significantly (p = 0.04)
higher at follow-up than at baseline. Weight loss was significantly
positively associated with changes in concentrations of all studied POPs
(2.0-2.4% increase per percent weight loss). Estimated mean intakes of POPs
(ng/day) remained stable because infant milk consumption decreased during
the study period. As infants gained weight, estimated mean intakes per kg
body weight decreased 17-22%. Changes in concentrations of POPs in HM
correlated positively with maternal weight loss, but it is unlikely that the
balance between the benefits and risks of breastfeeding will change if the
weight loss is restricted to 0.5 kg per week.


Human milk; Obese; Overweight; POPs; Postpartum; Weight loss


PMID: 27281542



[2] J Clin Endocrinol Metab. 2015 Dec;100(12):4463-71. doi: 10.1210/jc.2015-2571.
Epub 2015 Oct 15.

Pivotal Role for the Visceral Fat Compartment in the Release of Persistent
Organic Pollutants During Weight Loss.

Dirinck E(1), Dirtu AC(1), Jorens PG(1), Malarvannan G(1), Covaci A(1), Van Gaal

Author information:
(1)Department of Endocrinology, Diabetology, and Metabolism (E.D., L.F.V.G.),
Toxicology Centre (A.C.D., G.M., A.C.), and Department of Intensive Care
Medicine/Clinical Pharmacology (P.G.J.), Antwerp University Hospital, University
of Antwerp, 2650 Edegem, Belgium.


Full text: http://sci-hub.cc/10.1210/jc.2015-2571

CONTEXT: Polychlorinated biphenyls (PCBs), are implicated as potential endocrine
disruptors and obesogens. These lipophilic substances are preferentially stored
in the fat compartment and released into the circulation during weight loss.
OBJECTIVE: The aim of this study was to examine the contribution of abdominal
adiposity, and visceral adiposity in particular, to the increase of serum PCB
levels during weight loss.
MATERIALS AND METHODS: Fourty-five obese women were prospectively recruited.
Twenty individuals received dietary counseling and 25 underwent bariatric
surgery. Anthropometric data were collected and intra-abdominal adiposity was
assessed by measurement computed tomography scanning of the abdominal fat
compartment, delineating the visceral and subcutaneous compartment. Serum levels
of 27 PCBs were determined and the sum of all PCBs (ΣPCBs) calculated. Follow-up
measurements of anthropometric data, computed tomography scanning, and PCB levels
were performed after 6 months in all patients.
RESULTS: In patients who lost weight, serum ΣPCB levels displayed an increase
after 6 months of approximately 50%. Both correlation and regression analysis,
focusing on the relative contribution of the visceral vs the subcutaneous fat
compartment, suggested that the increase in ΣPCB serum levels after 6 months of
weight loss was more pronounced in patients losing relatively more visceral
adipose tissue. This trend could be established in the diet-treated, but not the
surgery-treated subgroup.
CONCLUSION: Our study suggests that the contribution of PCBs released from the
visceral fat compartment might be more pronounced compared with the subcutaneous
fat compartment during weight loss. These findings are present in the entire
study group whereas subanalysis of the diet vs surgery groups suggested the same
effect in the diet group but failed to reach statistical significance in the
surgery group. This suggests a possible weight-loss method-specific effect.

PMID: 26469381

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I'm hopeful that my POP load is a little lower than typical due to my wife and I, for ecological reasons, making significant efforts over the past 20 years to reduce our dependency on industrialized agriculture and producing significant amounts of food ourselves without the use of chemicals and seeking local organically produced foods for things we weren't producing ourselves.


But we weren't strict and I have no data.  Is there a recommended way to get some?  Perhaps a blood test for one or two of the most common dangerous POPs as an indicator of our total exposure?

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I took a cursory attempt to answer my question regarding testing for blood borne POPs, searching these forums and doing a few google searches but perhaps due to poor selection of keywords finding little of value so far.  I did find this service and am considering contacting them to see what they might recommend and the expense.




If anyone has already been through the process of exploring this sort of testing I'd love to hear about it.

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I've never investigated nor heard anything about organic toxin blood test services, including toxicreports.com. But if you talk with them, you'll definitely want to ask about whether they test for these three most common PCBs (from the full text of [2] above):


Among the PCB compounds detected in our population, PCB153 was the most prevalent congener, followed by PCB180 and PCB138.


BTW, the testing service used in [2] above was the Toxicology Centre at the University of Antwerp, so that probably isn't helpful. I did a quick check and it appears that the only toxin tests my favorite DIY blood testing services (privatemdlabs.com and LEF.org) offer are tests for heavy metals.


I'll be curious what you find out if you contact toxicreports.com. 



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This is good to know, and also resolves some things in my own mind.  For example, many people, and books, will say that it takes months to adjust to a low protein diet (for example when a heavy meat eater makes the switch to a plant based whole food diet) but after that you start to feel great.  For me it took nearly 6 months before I really felt like I was firing on all cylinders again when I made the switch to a plant based diet (but I've felt fantastic ever since).  MANY people will say "I tried a vegan diet and didn't feel good on it so I stopped" which countless people have attributed to low protein.  But that whole "low protein" thing as most of us know, is completely bogus, and it really never made much sense to me that the human body would "react badly" to low protein for 6 months only to start loving and thriving on it after that.  It is much more reasonable to attribute most or all of this "not feeling quite right" simply to the release of toxins from your fat as you shed all those extra pounds.  This is probably an even bigger issue for people who regularly take prescription drugs.


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