There is something rather disturbing happening behind-the-scenes in the Paleo community that I've seen unfolding before my eyes over the past six months or so. And in fact, it is becoming even more overt lately with various prominent bloggers writing about their questioning of long-term low-carb dieting for optimal health, including highly-respected people such as Dr. Kurt Harris, Stephan Guyenet, Richard Nikoley, Chris Kresser, Paul Jaminet, Danny Roddy, Dr. Garrett Smith, Matt Stone, and I'm sure many others. At the same time low-carb stalwarts like Dr. Jack Kruse have tried to bridge the gap that's beginning to grow between the Paleo and low-carb communities with a workable solution for us all to follow.

PaleoHacks.com featured a question last summer questioning whether Paleo is low-carb or not and noted this sudden shift away from the low-carb aspect that some people choose to include as part of their Paleo diet. It's all leading to a great deal of confusion and concern in the low-carb community with innocent people not knowing who or what to believe anymore. That's why this is disturbing to me and could quite possibly jeopardize the entire ancestral health movement if we're not careful to be mindful of the damage that is being done to the overall cause. There's still time to mitigate any damage that has been done and to unite behind the overall mission to help those people who just don't care about nutrition and how it impacts their health.

I will clear one issue up right away for the sake of getting it out there. No, a Paleo diet isn't necessarily a low-carb one. But as Professor Loren Cordain author of The Paleo Diet told me in a pre-interview chat I recorded last week (listen to the full interview airing on March 7, 2012 on The Livin' La Vida Low-Carb Show), "The evolutionary diet supports low-carb...it's a pretty good fit." When I brought up to him how I'm disheartened that there has been this sudden rise in antagonism about low-carb from the Paleo community lately, Cordain was quick to point out that, "It's very difficult to eat Paleo and eat high-carb. I don't think most people can do it." So what's the deal with all these subtle and not-so-subtle attempts to disparage a way of eating that is beloved by so many of us for being a lifesaver for our health?

It's no secret I'm a fan of low-carb diets (defined for me as 40g or less daily - others can certainly get away with more probably up to around 100g daily). After all, it was the high-fat, moderate protein, low-carb Atkins diet that helped me lose triple-digit weight in 2004 and attain some pretty remarkable changes in my health in the process that I still enjoy today. While I've been quite open about some weight management struggles as of late (which I'm working diligently with a doctor I trust to deal with it) despite shifting my diet to more of a Paleo-style approach with more grass-fed, pastured and organic foods in August 2011, I still couldn't imagine eating any other way than this. The quality of my diet in 2012 is light years ahead of what it was before 2004 when I transitioned from being a sugar-burner as my primary source of fuel to a fat-burner energizing my body with the power of ketones. It was a major shift that took place in my life over eight years ago and I've reaped the amazing benefits of it ever since in the form of improved lipids, controlled blood sugar, lower blood pressure, satisfaction with my diet without hunger, an active lifestyle working out several days a week, clearer thinking, and so much more than I could ever write down in one blog post. Even if I never lost another pound (and I expect that I will again someday), the health benefits that I've experienced eating this way have been worth it for me to keep doing it for the rest of my life.

But I was disheartened to read one of my fellow real food health activist bloggers named Ann Marie Michaels from the CHEESESLAVE blog write a post earlier this month called, "Why I Ditched Low-Carb" where she describes a whole laundry list of health problems she says she endured following low-carb. While I have a great deal of respect for Ann Marie and love what she has done to promote health from a traditional foods perspective, this one just threw me for a loop. I'm not saying she didn't experience these issues she is describing but I wonder how much of it can be attributed to her low-carb diet or something else. After reading her post, I summarized what I thought were her main criticisms of long-term low-carb diets that forced her to start adding carbs back into her diet again.

Here's what appears to be her primary objections to low-carb:
  • Thyroid function slows down causing T3 and reverse T3 signaling to become deficient on low-carb
  • Hypothyroid symptoms like hair loss, cold extremities, eyebrow thinning happen eating low-carb
  • You need to eat more carbohydrates in your diet and supplemental thyroid hormone in order to get pregnant
  • A 40-50% carb diet promotes fertility and athleticism, 30-40% carbs is a low stress diet
  • Eating low-carb lowers your body temperature because of a depressed metabolism
  • Adding carbs (upwards of 300g daily) back into your diet will dramatically improve your health by raising your body temp
  • Increased body temperature is an indication of improved adrenals and thyroid
These are the same kind of critical statements that I've seen and heard being made about low-carb diets across the blogosphere. It popped up in Part 3 of Chris Kresser's interview with Chris Masterjohn a few weeks ago when Kresser noted that many low-carb Paleo dieters in his practice are "suffering from the classic hypothyroid symptoms." And by adding carbohydrates back into their diet again they seem to anecdotally get better. He concluded that, "the low-carb diet contributing to hypothyroid and increasing carbohydrate intake improving thyroid function is definitely real." I look forward to exploring this topic further with Chris Kresser in Episode 10 of my new Ask The Low-Carb Experts podcast about "All Things Thyroid (Thyroid 101)" on March 22, 2012!

But is there any real evidence of this? When I don't definitively know the answer to something, I go to people who are a lot smarter than me to assist. And I just so happen to know a few good nutritional health experts I've been privileged to interview in hundreds of podcast episode over the years to reach out to for answers.

One of my Ask The Low-Carb Experts listeners asked my latest guest last week LIVE on the air in Episode 7 featuring Dr. Cate Shanahan about this brewing controversy over low-carb diets negatively impacting hormones like thyroid coming from the Paleo community and she was genuinely oblivious to it happening. I had already been working on this blog post asking various people in the Paleo and low-carb communities to chime in on that list of claims about low-carb diets and their impact on hormonal health. Here are the responses I got back beginning with Dr. Shanahan (who noted in my ATLCX podcast that she has revised her position on carbohydrates to be between 40-75g daily instead of 100g) who offered up her thoughts and concerns about these issues:
This just so happens to be an issue I've been pondering since reading about the controversy over safe starches, and a couple pieces of the puzzle recently fell into place that I think I add up to at least one explanation for the debilitating symptoms some people develop when going low-carb, and offer a method for anyone on low-carb to do so without problems.

Below are the bullet points of what I've concluded so far, and the details are fleshed out in this blog post on my website DrCate.com:
  • Problems arise in those who have gone from high-carb to low fairly abruptly
  • In these cases, we see high rT3 and sometimes high LDL
  • Supplementing with T3 seems to help, at least a little.
  • This set of symptoms is very similar to the so-called Hibernation Syndrome
Newly discovered compounds called thyronamines, derived from rT3 and produced by the liver and other tissues may be the cause of hibernation syndrome. They appear to play a very important role in making all the needed metabolic adaptations for a prolonged winter fast. By going from high-carb to low-carb relatively abruptly, people mimic the nutrient changes associated with pre-hybernation binging. This may, in some people, flip an atavistic hibernation switch and initiate the conversion of T4 into rT3 instead of T3. Once we make rT3, our tissues can convert it to thyronamines to cause a variety of symptoms consistent with hibernation syndrome.

What's the solution? Go slow! In my T.R.I.M. program, I introduce low-carb meals one at a time over a course of 6-12 weeks, beginning with breakfast.

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Dr. Shanahan promotes a "gradual" approach to cutting carbs that may keep these criticisms about low-carb diets from being valid. Of course, there are others who wonder why we're even talking about this since there doesn't seem to be any science behind it to back it up. Dr. Peter Attia from the "War On Insulin" blog asked, "What is the proof or data supporting these claims? It's best to address this by examining the data supporting this position, it seems? These aren't folks talking about science, they are stating their experiences and opinions, as far as I can tell." He said he plans on writing a series of posts addressing these issues in the coming months.

Dr. Spencer Nadolsky says, "I have heard all of these (claims about low-carb diets) before and I have always asked for references. I only hear anectdotal evidence which is obviously not the best." Dr. Nadolsky goes on to say that, "What we really need to see is if someone on a keto-adapted diet with enough fat (aka energy) in the diet would product the same effects. I have never seen anything that shows that this is the case. If they can find that then they have a case." He said much of the supposed evidence presented is too short-term to offer any solid convincing arguments about this subject.

Swedish LCHF physician Dr. Andreas Eenfeldt said, "When it comes to hypothyroidism on low-carb I have not seen any studies showing this, nor have I seen it in my patients or heard about it from other doctors practicing low-carb for a long time. I doubt it's true. Personally I think this whole hypothyroidism/adrenal fatigue thing is a very alternative theory without much credible science to back it up. Generally I don't think it makes much sense."

These medical doctors weren't alone in the desire to see more evidence. Biochemistry professor Dr. Wendy Pogozelski (aka "Dr. Pogo" who I interviewed on my podcast here) said that she has, "never seen any real studies to support this claim." She added, "I believe that there are anecdotes to say that MANY dieters, whether low-carb or low-fat or low-calorie, experience a slowing of their thyroid function (Oprah Winfrey is a good example and her dieting was low-fat/low-carb). I'd say 'show me the science' before I believe that the effect is limited to low-carb eating or that any reduced thyroid hormone signaling outweighs the benefits of carb restriction for many people." Dr. Pogo's fellow biochemistry colleague Dr. Richard Feinman stated that he is not aware of any low-carb papers that bear on thyroid but would be delighted to take a look at any if they exist. He concluded, "If these guys (the critics of low-carb diets) have found a non-low-carb way to eat, they should go for it. If they want me to switch to it, I'm simply not in the market." Me neither Dr. Feinman.

Jackie Eberstein, a registered nurse who worked with the late, great Dr. Robert C. Atkins for nearly three decades, says her experience with patients on low-carb diets was that they got better not worse once they got their diet and hormonal health markers in order.
I'll start by saying that I spent too many years seeing patients get healthier on an Atkins Lifestyle. Many patients who came to us already had hypothyroid symptoms, low body temps even after spending years on Synthroid. Many also had low DHEA levels that once addressed could improve thyroid function.

Eating low-calorie and weight cycling I believe slows metabolism. Not low-carb if calorie intake is adequate. We also did not see many patients with high reverse T3.

As far as needing more carbs to get pregnant this was not my experience especially in women with PCOS. We cautioned our patients if they did not want to get pregnant they needed to use birth control.

I am not aware of any of the low-carb studies, even those up to two years, where low thyroid symptoms suddenly appeared during the study.

On another point there are certainly people whose metabolic situation won't allow anything other than a low-carb intake and even 30-40% carbs would be too high. It would also be too high for those people who are carb-addicted.
Low-carb triathlete Ben Greenfield, author of The Low-Carbohydrate Guide For Triathletes, identified four studies that he is aware of that address low-carb and thyroid health and offered commentary on each of them: Nora Gedgaudas from Primal Body-Primal Mind chimed in on this stating that the "thyroid thing is pretty overblown."
I have personally never seen the problems you are asking about as a result of the diet I recommend. I think if one is going to have problems with low-carb (relative to your list) its mainly going to be seen in conjunction with low-fat, biliary problems and/or overly high protein. The problem isn't a lack of carbs but a lack of sufficient fat, poor biliary function (and therefore poor utilization of fat) or an inability to effectively utilize ketones due to an unwitting sustained dependence on glucose through excess protein (converting to sugar to keep the primary glucose dependence going). Dr. Richard Bernstein has talked about this. The idea that carbs are or ever were essential to us dietarily is absurd. How on earth would we ever have survived any Ice Age and how would the Inuit have ever survived as a people? I have thyroid problems left and right in my family and so far I'm the only one that's dodged that bullet - and the only one that's low carb. Look ma...no eyebrow thinning!
Denver's Diet Doctor Jeffry Gerber believes one of the problems is the difference between why people go on a low-carb diet vs. the Paleo diet.
Most doing low-carb diets need to lose weight and sometimes lots of weight. My patients in a family medicine office tend to be overweight and already have medical issues as opposed to the Paleo community, with their muscles bulging ultra athlete, CrossFit crazed group that they are. The Paleo community are looking at maximizing and optimizing performance, the low-carb people usually have weight loss and health issues to address. Different goals and different diets, not that one is better then the other, they both excel in the proper circumstance. I use both in my office.

I must say the issues raised by the Paleo group regarding low-carb diets are theoretical and I do not observe, nor can I measure, any of this within the medical office setting. What I do measure in my office is cardio-metabolic markers such as cholesterol, lipids, LDL particles, APO-B, LDL sub-fractination, cardiac CRP, HgA1c, C-peptide, TSH, etc. These numbers ALWAYS improve if patients can lose weight.
Dr. Ron Rosedale, who infamously had a friendly exchange of ideas over Paul Jaminet's "safe starches" concept, weighed in on the thyroid concerns of low-carb diets. He argues that eating carbohydrates wreaks more havoc on health than low-carb diets ever will.
I believe that those who advocate for higher starches and many if not most in the medical and health community, misunderstand the physiologic response to low glucose, and the true meaning of low thyroid. It is extremely important to have the confusion and misunderstanding of the true meaning of free T3 and body temperature being lowered, resolved.

Glucose scarcity elicits an evolutionary response to perceived low fuel availability. (In all but frank hypoglycemic crisis, glucose deficiency is a misnomer.) This results in a shift in genetic expression to allow that organism to better survive the perceived famine. Intracellular antioxidant systems, heat shock proteins, DNA repair, autophagy, all tricks that nature has, are upregulated to allow the organism to increase repair and maintain itself to remain healthy and alive. As part of this genetic expression, and as part and parcel of nature's mechanism to allow the maintenance of health and actually reduce the rate of aging, certain events will take place as seen in caloric restricted animals. These include a reduction in serum glucose, insulin, leptin, and free T3. The reduction in free T3 is of great benefit, reducing temperature, metabolic damage and decreasing catabolism. TSH is not elevated. We are not talking about a hypothyroid condition. It is a purposeful reduction in thyroid activity to elicit health. Yes, reverse T3 is increased, as this is a normal, healthy, physiologic mechanism to reduce thyroid activity. It is not always a sign of malfunctioning thyroid as is frequently taught, but is instead one of the redundant ways that thyroid action is controlled.

Furthermore, in caloric restricted animals where body temperature and free T3 are reduced, the immune response is markedly increased, not reduced as opponents of VLC diets often maintain, and CR animal's mortality rate is well known to be significantly reduced while lifespan significantly increased. There is also a huge reduction in autoimmune diseases, secondary to improving immune function, not lowering it.

Again, I am not talking about a sick thyroid. I am not talking about a thyroid that is low because it has to be, or a body temperature that is low because the body does not have enough lean mass or proper physiology to maintain a higher temperature. I am not talking about hypothyroidism. I am talking about a thyroid that is purposefully being lowered to enhance the wellness and survivability of life. Please understand that this is very different. One is very healthy; one is very not.

This is analogous to fasting insulin. Almost always, a high fasting insulin indicates insulin resistance and poor health. Properly treated, fasting insulin goes down and the person is healthier. You don't say that that person now has a sick pancreas. The same is true for thyroid. As part and parcel of making that person healthier, fasting insulin is reduced, fasting leptin is reduced, and so is free T3 reduced.

One can certainly have low thyroid hormones because of sickness, or because of a primary sick thyroid. I can give the more extreme example that body temperature is lower when one is dead. In calorie restricted animals and in those on my diet, on the other hand, free T3 and body temperature are reduced as part and parcel of a shift in genetic expression towards maintenance, repair, and longevity, in the same way that the temperature of your car is reduced when it is functioning best; when it is getting the best mileage, has the best acceleration, and where the engine will live longest. In both cases, it is making the best use of available resources, and wanting to reduce waste. In the former, thyroid is low because it is sick. In the latter, and with my diet, thyroid goes lower to keep one healthy. If the car is running hotter, you know that is sick. It does so because it must and perhaps better than not running at all.

Temperature must be orchestrated for maximal health. As we age, one of the major problems is that our temperature does not go as high with infection as it did when we were children. This can predispose to serious infection. My diet does not relegate people to low temperature. It keeps temperature a little bit lower when that is healthiest, but does not prevent a rise in temperature, a fever, with infection, but instead would promote it. This is very healthy. Having a "fever" when not necessary, and is promoted by the thermogenesis of burning 'healthy starches' and excess protein is what is not.

Furthermore, it is now a fairly well established finding that free T3 is reduced in centenarians. One example;
"A cross-section analysis of FT3 age-related changes in a group of old and oldest-old subjects, including centenarians' relatives, shows that a down-regulated thyroid function has a familial component and is related to longevity" Age and Ageing 2010; Andrea Corsonello, et al 39: 723 - 727
"Down-regulation of thyroid hormones, due to either genetic predisposition or resetting of thyroid function favours longevity."

The key is that we can reset our thyroid function to be that of centenarians, even if we were not so genetically predisposed. We can make our own luck, but not by adding carbohydrates..

If ketone production is an indication of fatty acid utilization as fuel, and if this is a marker of a shift in metabolism towards that seen in caloric restriction that has been shown to confer tremendous health benefits including longevity, then what Cahill states must be strongly noted; as little as 100 gms. of carbohydrate that higher starch advocates promote, will prevent this. (Fuel Metabolism in Starvation Annu. Rev. Nutr. 2006.26:1-22. George F. Cahill, Jr. Department of Medicine, Harvard Medical School)

That gets us to the main issue and most important question; is there a diet or glucose (starch) intake that can better maximize the repair/damage ratio that life, health, and youthful longevity depends on?

'Safe starch' and higher carb advocates say that their diet would not have the effects on thyroid as my diet, namely lowering T3, and they are likely right; see below. However, they believe that lowering thyroid is disadvantageous. It is far from; in fact quite the opposite. The purposeful lowering of thyroid likely helps to mediate metabolic advantages that help confer longevity in centenarians and in calorie restriction. Note that The holy grail of aging research (including the giant pharmaceutical corporations) has been to find a way (drug) to mimic the effects of calorie restriction (that has been shown to greatly improve health and increase maximal lifespan in almost every species studied since the 1930s) without having to do so.

In the study cited previously, [In centenarians] "Down-regulation of thyroid hormones, due to either genetic predisposition or resetting of thyroid function, favours longevity."

...as my diet has been shown to do.

And the effect of calorie restriction on thyroid;
"Effect of Caloric Restriction and Dietary Composition on Serum T3 and Reverse T3 in Man" The Journal of Clinical Endocrinology & Metabolism Jan1, 1976 vol. 42 no.1197-200

Subjects receiving the no-carbohydrate hypocaloric diets for two weeks demonstrated a similar 47% decline in serum T3 [as caloric restriction] ... In contrast, the same subjects receiving isocaloric diets containing at least 50 g of carbohydrate showed no significant changes in either T3 or rT3 concentration.
Very low carbohydrates such as mine has similar effects on thyroid as caloric restriction. Keep in mind that I do not calorie restrict. People are told to eat whenever they are hungry, except for 3 hrs before bedtime.

Of interest is that the authors' note in this study that the (isocaloric) addition of 50 gm of carbohydrate totally reversed this beneficial effect of lowering T3.

Some more clues..
"Centenarian indicators of longevity; Evaluation of neuroendocrine status in longevity." Neurobiol Aging. 2007; 28(5):774-83 Baranowska B

Our data revealed several differences in the neuroendocrine and metabolic status of centenarians, compared with other age groups, including the lowest serum concentrations of leptin, insulin and T3...
"Calorie Restriction indicators of longevity;
The Fall in Leptin Concentration Is a Major Determinant of the Metabolic Adaptation Induced by Caloric Restriction Independently of the Changes in Leptin Circadian Rhythms." The Journal of Clin. Endocrinology & Metabolism Sept 1, 2011 vol 96, no 9 Virgile Lecoultre, Eric Ravussin and Leanne M. Redman

Leptin is involved in the hormonal regulation of the reproductive, somatotropic, thyroid, and autonomic axes and ultimately in the regulation of energy balance. In parallel to the metabolic adaptation observed in response to caloric restriction (CR), plasma leptin concentrations are substantially decreased... Conclusion: Our results confirm an important role for leptin as an independent determinant of the metabolic adaptation in response to CR.
Note also that the reduction in leptin may be primary to elicit the metabolic adaptations of caloric restriction, including the reduction in thyroid/free T3, and therefore the extreme beneficial effects on health and lifespan. That brings us to my study;
"Clinical Experience of a Diet Designed to Reduce Aging" Journal of Applied Research, vol 9, no 4, 2009 Rosedale, Westman, Konhilis

This retrospective analysis of patients from a private clinic adhering to a high-fat, low carbohydrate, adequate protein diet [the Rosedale diet] demonstrated reductions in critical metabolic mediators including insulin, leptin, glucose, triglycerides, and free T3... Patients in this study demonstrated a similar directional impact on the measured parameters when compared to studies using more established models of longevity such as caloric restriction.
We may have found a way to mimic caloric restriction, at least to some extent and any extent is extraordinary. It appears that my diet can mimic the hormonal changes in T3, insulin, and leptin seen in calorie restriction studies that are instrumental to mediate the major physiological and extremely beneficial effects of calorie restriction, but without having to calorie restrict. There are no studies that indicate that a higher carbohydrate diet would have similar benefits. However, there are clues that it would not. Cahill has shown that a carbohydrate intake of 100 grams/day reverses ketoses, impedes the ability to burn fat, and likely prevents the full physiology and genetic expression of health and longevity as revealed by caloric restriction. Furthermore, adding 50 gm of carbohydrate may at least contribute to reversing the beneficial effect of lowering T3 that mediates much of the advantages of CR, as shown in the above study. 'Safe starch' diets add double that intake.
Holistic psychiatrist Dr. Judy Tsafrir says she is "puzzled" by the anti-low-carb sentiment that seems to be running through the Paleo/ancestral blogosphere.
I don't really get it. It seems very clear to me that most peoples' health is vastly improved by a moderately low to very low carb diet. I am of the mind set that the specific source of the carbs matters. For people who have been formerly obese, their metabolism is often significantly damaged, and they could never eat upwards of 300g of carbs a day without gaining weight and having a recurrence of metabolic syndrome.
She added her thoughts on hypothyroidism being indicative of a high-carb, not low-carb, diet.
My thoughts are that hypothyroidism is very common among people eating a high carbohydrate SAD diet. Symptoms such as hair loss and feeling cold are not unusual symptoms among dieters, particularly those who lose significant amounts of weight. Any diet that is too calorie restricted, or combined with excessive exercise and or stress/poor sleep could cause such symptoms. Additionally, it is well established that persons who lose large amounts of weight, however they lose it, may and typically do, experience long-term cold intolerance and alterations in metabolism. ANY diet which is too energy (calorie) restricted may decrease metabolism. And science points to virtually all significant weight loss producing changes in metabolism and often, as previously stated, in experience of temperature, ie., feeling cooler. Adding carbs back in that drive weight gain and the recurrence of serious medical conditions is all too common.
Reproductive endocrinologist Dr. Michael Fox who regularly studies the research behind carbohydrate-restriction and uses it with his patients who want to get pregnant offered up a different point of view on this jaded view of low-carb diets on thyroid health and fertility.
My initial and summary response to these allegations regarding low carbohydrate diets is that each of these thoughts are categorically wrong and go against the conclusions of all of Weston Price's research and findings. His findings are landmark and timeless, probably representing the most extensive look at primitive diets and populations ever done and because the societies are no longer in existence, his work can never be reproduced. It is odd that anyone who has read his book and analyzed his findings would come to any of those conclusions.

Decrease in metabolic rate due to incomplete T4 to T3 peripheral conversion. / hypothyroid symptoms increase. / Lowers body temperature and depressed metabolism. / adding carbs raises temperature and improves health. All these ideas follow the same physiologic response:

Lowering body temperature and metabolic rate via thyroid hormone and increased adrenal activity (cortisol) is a stress response mechanism in place to survive starvation stress and is activated in other hypothalamic stress situations such as excessive exercise. Probably the biggest trigger for this response in people today is hypoglycemia, a phenomenon exclusive of carbohydrate rich diets. In contrast, people on low carbohydrate diets have very stable blood sugars removing the powerful stress stimulus of hypoglycemia or low blood sugar. Our experience in reproduction also supports this physiologic response. For patients who are underweight, over exercised, Insulin resistant with reactive hypoglycemia, and those pursuing low calorie but normal to high carbohydrate nutrition plans (starvation diets) are at the highest risk of this Thyroid / Adrenal reaction to physiologic stress. Bariatric surgery patients who are forced into low calorie but usually maintain relatively high carbohydrate intake have a particularly severe form of this response. The fact that the body is responds to reactive hypoglycemia with this "stress response" is clear evidence that moderate to high carbohydrate nutrition and it's subsequent hormonal responses (elevations in insulin, cortisol, epinephrine, growth hormone, endorphins, etc.) are toxic to human physiology.

These patients all complain of lower body temperature and cold hands. TSH levels are mildly elevated and T4 / T3 levels are low normal to slightly low in these patients (relative hypothyroid pattern). Universally when their diets are converted to high fat very low carbohydrate, they warm up and feel much less stressed due to the blood sugar stabilization and reduction in stress response.

Eating 40-50% carbohydrate diet promotes fertility and athleticism: When we treat both normal and insulin resistant patient with ketotic, very low carbohydrate and high fat diets, our pregnancy rates increase 2-3 fold. The female reproductive hormonal system is the most sensitive endocrine system in humans. If ketotic diets were harmful or produced stress, fertility would be the first to go and pregnancy rates would plumet, not increase as they clearly do.

In regards to athletics, carb loading was originally described for marathoners and other extreme exercisers. This was based on the increase in glycogen stores. At the rate of useage in these activities, carb loading only buys another 15-30 mins of exercise before glucose stores are depleted from the liver, muscle and kidney. In high carb diet athletes, when glucose runs out, it must be replenished, hence the need for liquid sugar, like gatorade. This is due to an inability of these individuals to significantly draw on fat stores for energy. Many high athletes are turning to high fat low carb ketotic diets, to allow for the continued useage of stored fat during the event. From personal experience, I can exercise at maximal levels for more than an hour without signs of hypoglycemia.

I hope these comments will help readers understand that the allogations against low carb diets are completely unfounded in physiology.
So now that we've heard a defense of low-carb diets from some of the most ardent supporters in the medical and research realm, what do some of the more prominent members of the Paleo community think about all of this growing antagonism about low-carb coming from their peers? I asked Robb Wolf about it and he typed in "ketogenic diet hypothyroid" on PubMed to see how many results there are. Wanna know what he found? "Not a single damn reference on PubMed. There are some folks trying to carve out a niche by really muddying the waters on all this. It's not doing (overweight and metabolically challenged) folks a favor in my opinion." Interesting. Jamie "That Paleo Guy" Scott reveals there are many "confounding factors" at work here that make this a lot more complex than meets the eye.
When people first move from a conventional low-fat approach and begin to open themselves to either a paleo or low-carb approach, you see people cutting their carbohydrates, and specifically cutting these from grain and fruit-based sources. They often gain a lot of health traction from this approach, though I am not entirely convinced that we can measure this on the basis of carbohydrate content alone. What you often also see is a reluctance to push fat intakes up, or it is only done minimally. This may be due to a persistent fear of fat, or it may be that a person decides in their mind that if they go low carb AND low fat, they will get better results (indeed, many of the body building-type diets are variants of low-carb, low-fat, high-protein diets - and you usually see the wheels fall off people inside 6-8 weeks). It could also be that, after many years of poor eating, that digestive capacity is low and people feel quite unwell eating the likes of fatty meats - the fat can go right through them.
Grace "Dr. B G" from the Animal Pharm blog says she has observed that ketosis can "bring about a compromised adrenal and low thyroid state." But that doesn't mean we should all start eating a bunch of carbs to compensate.
I'd disagree with the statement that a thyroid supplement and 300g daily carbs are required. The standard adrenal recovery and optimization protocols rely on 150g daily carbs. Certain people may require more I believe (i.e. athletes) and certain individuals may require less.

PCOS is one kind of infertility which is reversed by low-carb and ketotic diets when insulin and leptin sensitivity are reclaimed. However this will not be the case in those with severe adrenal dysfunction.

These questions and the debate of the role of carbs are important especially in the context of multiple endocrine organ dysfunction (i.e. gonads, thyroid and adrenals). I say this because adrenal dysfunction is largely unrecognized but is EPIDEMIC. Even children and teens suffer from adrenal and thyroid issues.

And it's not from low-carb diets!

Yes, ketosis and intermittent fasting are problematic for a TON of people if folks whether they are trying to get pregnant, leptin resetting, trying to increase free testosterone, lower estrogen dominance or just trying to lose body fat. It's not that complicated but for those who have no problems with ketosis, I suspect they are not likely to 'get it.' I went into adrenal and thyroid dysfunction with intermittent fasting which put me in ketosis. Overtraining and CrossFit hastened the health decline. Not everyone has Kevlar lined adrenals!
Dr. Emily Deans from Evolutionary Psychiatry is one who thinks there is some validity to the arguments made about low-carb diets and thyroid levels.
There is no question that starvation, fasting, and a VERY low carb diet will lower T3 levels. It is not the same as true hypothyroidism as TSH often is low or low normal as well, and with a true primary thyroid gland problem, TSH will be very elevated. It seems reasonable to speculate that the body will work to increase energy efficiency in a state of fasting or starvation, it is possible that lower T3 will do this, and it MAY be this change in thyroid function is responsible for some of the speculated longevity effects from a low carb diet. Certainly the process is very reversible with eating more carbs and does not represent any damage to the thyroid.
As for the symptoms of hypothyroidism, Dr. Deans explains:
In my own experience, fasting in the winter time causes me to have cold extremities. There is also a noradrenergic effect which may be responsible. It seems unlikely a run of the mill low carb diet would cause these problems. Add in lots of fasting and ketosis, I suppose you could overdo it.
On the lower body temperature issue with low-carb diets, she concludes that "fasting definitely does" and that "very low-carb might do this to some." Dr. Dean observed that she's not aware of any endocrinologists who track morning body temps to determine the health of a patient's metabolism. Regarding the "accurate" signs of hypothyroidism that people should be looking for, she listed "low pulse, decreased reflexes, a certain pallor and lack of energy, hair falling out, and depression." I didn't see anything in there that low-carb diets necessarily are contributing to.

As far as adding more carbohydrates and supplementing with thyroid hormone to get pregnant, Dr. Deans believes it is "an issue of context" depending on who you are and what the purpose of doing so would be.
Many women nowadays are infertile due to PCOS, which is known to respond well to a low-carb diet due to the insulin resistance. In that case, I think low-carb diets would increase fertility. The only situation I'm aware of regarding supplemental thyroid hormone added to very low-carb diets was Chris Masterjohn's anecdote of the moose thyroid eating young ladies of the far north. It's an interesting anecdote, but I'm not aware of any OB/GYN's pushing supplemental thyroid hormone unless someone is truly hypothyroid. If you have symptoms and low T3 and eat very low-carb or are fasting a lot and can't seem to get pregnant, it does seem reasonable to increase the carbs rather than supplementing with thyroid hormone. I'm not a big fan of counting macronutrients as you know. The very low-carb diet is a physiologic extreme with a number of interesting metabolic consequences, some of which could conceivably be very favorable in the case of certain types of cancer, epilepsy, dementia, possibly in bipolar disorder and schizophrenia. There may be elements to that extreme that are not favorable for others, such as athletes, for different reasons.
Diane Sanfilippo from Balanced Bites notes that carbohydrate intake on Paleo depends on the activity of the dieter and their nutritional history.
From the practical implementation side of things... while I don't have clients who are eating 300g or so of carbs/day simply for general health, I absolutely see how it can be a valid approach for some people who have been eating low-carb for a while without benefit or with halted success, and especially for athletes. I don't honestly believe that carbs are inherently bad or are what contributes to metabolic derangement. I think that BAD carbs are bad: refined/processed foods and foods devoid of bioavailable micronutrients to help us to metabolize the carbohydrates and provide adequate fuel for our cells. I can't see how whole foods that we've survived on for thousands of years would be problematic except in the case of a modern world wherein a person may be dealing with food addictions or, again, metabolic damage as a result of the aforementioned types of bad carbs.
She does think if someone starts feeling horrible eating a low-carb diet that they should shift to eating more carbs to figure out what works well for the individual.
I certainly am not seeing clients who have eaten lots of sweet potatoes or fruit all their lives) as opposed to refined/modern foods) struggling with their carb intake and metabolic derangement/weight lost resistance. When people got hooked on sugar, grains and refined/modern foods, the problems began to mount. So, my point is this: while I generally eat fairly low carb and will recommend that people eat lower carb (under 150g) if they are less active, I certainly would never rule out the option of adding carbs back in and rebalancing macronutrient ratios of someone's intake differently if their low-carb approach wasn't working for them anymore. Why keep plugging away at a way of eating that isn't working for you and you don't FEEL well? I think it's all about finding out what works for each person, and then going with it, knowing that that may change periodically.
Diane says many Paleo dieters end up eating low-carb by default when they forget to include dense carbohydrate sources in their diet.
I think one of the BIGGEST mistakes a lot of people make when they go Paleo is that they forget that eating dense carb sources wasn't the root of their problems, but often they just stick to other vegetables and almost mistakenly end up on a low-carb path and possibly discover ill-health side effects as related to cortisol and thyroid disregulation after some time into their new lifestyle. I send people to my FAQs post frequently to help them discover dense sources of Paleo carbs, and I certainly hold no dogma around a low-carb approach being healthier for every person.
And finally, we hear from Beyond Caloriegate e-book author Adam Kosloff who is perplexed by the "extravagant, circus-like debates about diet."
Let me get this straight. Adding 300g of carbs to your diet will improve your health by raising your body temperature? Low carb is bad for your eyebrows? Maybe bleeding people with leeches fixes the flu, too. And burning witches at the stake makes it rain. Ya never know.

Look, I can't comment on the science, or should I say "science," behind these critiques. Not because they might not have merit. They might! Frankly, we lack the long term, controlled studies on low carbing we need to answer all the nitty gritty questions. At some point, we all grade into the realm of "making stuff up" because the science is so often so poorly done, ambiguous, badly communicated and summarized, and, at best, hard to apply broadly.

So why do we insist in indulging in these extravagant, circus-like debates about diet minutiae? My friends: science is not extravagant. Science is a brutal, blunt instrument. When we try to sell people on packaged solutions - like "perfect" diets that have something to say about every food group, macronutrient, micronutrient, protein, enzyme, etc - we are going way, way, way beyond the mandate of actual science.

And I empathize - it's tricky! Ordinary people who just want to lose weight and call it a day need structure. They need the 7 Simple Fat Loss Steps for Stupid People, or whatever. Because they don't have the time, patience or skill to navigate the labyrinth of "diet myths...or are they really??" that have been spun for them.

That said, we in the low carb/Paleo world have a serious forest-for-the-trees problem, if we're spilling our virtual ink debating questions like these. Ding ding ding! There's a massive obesity epidemic going on that's crippling America and killing millions. We need to deal with THAT. All attention on THAT. Enough "low carb thins your eyebrows" talk. Because even if it does, WHO CARES? Low carb/Paleo is likely our best weapon in the fight against obesity. If your house is on fire, and a fireman comes to the rescue with a hose, are you really going to kick the guy out if he steps on a piece of your fine china while fighting the blaze?

Enough rearranging the deck chairs. The Titanic is SINKING.

We are debating Level 10 "stuff" (e.g. "Does low carb thin the eyebrows, long term?") when we can't even get our act straight about the Level 1 "stuff" (e.g. "What causes obesity? Eating too much, or insulin's impact on the fat tissue?").

Speaking of which, I am also baffled that so many high profile thinkers in the low carb/Paleo realm appear to be willing to toss the carbohydrate-insulin hypothesis into the junkheap and replace it with fever dreams about "food reward". But that's another axe to grind for another day.

Here's the real issue here. The fundamental one. We are focusing on the wrong constraints, when it comes to communicating with each other and with the world at large. Does it make logical sense when someone calls the Paleolithic diet a "fad diet"? Of course not! Paleo is literally the opposite of that, prima facie. What holds people back from "buying into" the Paleo/low carb message is (in general) EMOTIONAL resistance, not intellectual resistance. Fear, anger, frustration, bafflement, etc. These emotions are expressed in terms of intellectual counterarguments. But at the root of the resistance are feelings/needs that are not getting met. We all have needs to be heard, to understand, to be part of a tribe of like minded people, to make important contributions. When those needs aren't met, wars, rhetorical and otherwise, break out.

A more productive debate would be: how can we get everyone's needs met? And by everyone, I mean everyone: low carbers, anti-low carb Paleos, vegetarians/vegans, USDA officials, corn syrup manufacturers, etc. Let's rise above seeing people as "enemies" or even "allies" and recognize the binding humanity in all of us. We have a major challenge on our hands - the Titanic is sinking! - and we need all hands on deck.
I agree Adam. I've been scratching my head over all this talk about what low-carb is supposedly doing to people's health long-term coming from people who I would consider allies in this debate of ideas. As Dr. Feinman noted, if you're able to eat more carbohydrates and not have it negatively impact your health then GO FOR IT! But the overriding message we need to be sending the general public is that they are being fooled into thinking a low-fat diet with "healthy whole grains" and vegetable oils is the optimal way to eat is dead wrong. Unfortunately, for many of them, they have been eating that way for so long that they come to low-carb or Paleo or whatever with comprised hormone and metabolic issues that will need to be addressed. It's not the low-carb diets that are necessarily leading to these issues. People who tend to land on low-carb have already been through the wringer and back trying to attain the best health possible for many years following inferior dietary advice. Perhaps a low-carb Paleo diet is precisely what is needed to slow and maybe even halt the damage that has been done.

Rather than being critical of this way of eating with people who are on the same team, why not acknowledge that more research needs to be done on these theories that have been written about? And in the meantime why not walk alongside those of us who do choose to eat more of a very low-carb (under 50g daily) diet as a means for healing the damage that has been inflicted from so many years of poor nutritional choices that have gotten our hormones and bodies off kilter? There's power in numbers and we are not as strong if we allow ourselves to become fractured by the minutia when the big picture still isn't in focus for the hundreds of millions who desperately need to hear our message.

Let the discussion begin. Your comments are welcomed and encouraged.