I don't have real problems with 1 & 2. It's been shown that humans evolved eating a variety of diets. The diseases of civilization engulfing us today have less to do with macronutrient ratios than food toxins (wheat, gluten, casein, refined sugar, refined/pulverized flour). These food toxins all happen to be carbs. That does not mean all carbs are bad. That's what some people seem to miss.

Now, if you have diabetes, you may need to give up safe starches (rice, potatoes, sweet potatoes, yams, cassava, turnips, etc.). That's probably obvious.

But it's pretty clear that those tribes that subsited on carb-heavy tuber or even rice diets never contracted diabetes. It was the onslaught of refined sugar/fructose and white flour which is wreaking havoc.

It's also easy to imagine that most tribes ate a carb-heavy diet. It's simply not that easy to subsist on a carnivorous diet. You have tubers that are simply too easy to pass by. Hunting does not always lead to a successful catch. You can go days witout a catch. Also, you couldn't really store your catch.

Now for #3: Perhaps he means potatoes and yams induce initial satiety (they do). I don't think though they cause you to eat less at subsequent meals. They seem to whet your appetite for more food, starch or otherwise.

I love Stephan's comment, and see criticism of it as a microcosm of a major paleo problem. That problem is "taking your experience and view of the literature as paleo gospel".

Here are some things that have been mentioned as fact around paleohacks in the past few months:

• Eating more than a few grams of fructose per day will kill you
• You can't lose weight on a carb heavy diet
• If you have health problems, you must switch to a high-fat diet

And here are things that have been largely ignored:

• The liver is a marvelous organ that we don't always have to treat like a delicate little flower
• Many cultures have thrived with moderate amounts of prepared/fermented grains and beans (i.e. WAPF)
• One's personal reading of the literature not only doesn't reflect the literature as a whole, but the literature as a whole is a very incomplete reflection of reality.

I have no doubt that Stephan will explain more in later posts. It is one thing to talk about how we can eat no carbs and live, or study Inuit. It is another thing to wade through reading about long term ketogenic diets. Eating a diet consisting of tons of meat every single day, supplemented with extra fat, should not necessarily be considered the automatic winner among best human diets. Note that Stephan does not generalize this at all to medical conditions (e.g. diabetes), and is more careful about making definitive statements than many on paleohacks.

I wasn't even going to comment, but what I have seen here so far is the failure to perceive Stephen's statements for what they really are; "Emperor's New Clothes" i.e. statements riding mostly naked. There may be explanations in the future from Stephan that might dress up and explain the statements, but currently there are none.

Our ancient ancestors likely did not eat significant digestible carbohydrates, as the increasing size of our brain and its concurrent metabolically expensive energy expenditure could not likely have evolved on a high carbohydrate diet. The so-called “Expensive Tissue Hypothesis” that is quite famous and popular in paleoanthropology and likely would have already been discussed in this and other paleo blogs previously, describes this. For those unfamiliar, the citation and abstract is below. However, the belief in this "hypothesis" and even what our ancestors ate are moot points anyway. What our ancestors ate is irrelevant for longevity and post-reproductive lifespan. Diets evolved for reproductive success. I have discussed this recently in prior posts.

Whereas I commend Stephen for putting the major onus of obesity and health onto leptin, it appears that he is making a couple of basic mistakes regarding hormone signaling in general, especially pertinent to insulin and leptin. When endogenous hormones such as insulin and leptin do their job, they will keep you healthy. However, it is not the size of a signal that is relevant, but the accuracy of what's "heard". Metabolic diseases, and in fact all diseases, are secondary to miscommunication. The problem with insulin and leptin is not insulin and leptin per se, but insulin and leptin resistance when they cannot get their messages properly heard. The body, and in particular the brain, then responds to high insulin and leptin as if they were low. Stephen seems to miss this in his current post, and more importantly the cause(es) of this. I firmly believe that the major cause of both insulin and leptin resistance is repeated spikes in both of those hormones secondary to spikes in blood glucose, so where there might arguably be a short-term benefit from a spike in insulin and leptin, long-term spikes lead to a reduction in signaling, and more importantly a corruption in the where, when, and how the signal is being received by different organs and cell types.

Also ignored in the post is the copious amount of research over the last 15 years linking elevations/spikes in insulin and glucose with accelerated aging.

The Expensive-Tissue Hypothesis: The Brain and the Digestive System in Human and Primate Evolution Author(s): Leslie C. Aiello and Peter Wheeler Current Anthropology, Vol. 36, No. 2 (Apr., 1995), pp. 199-221

Brain tissue is metabolically expensive, but there is no significant correlation between relative basal metabolic rate and relative brain size in humans and other encephalized mammals. The expensive-tissue hypothesis suggests that the metabolic requirements of relatively large brains are offset by a corresponding reduction of the gut. The splanchnic organs (liver and gastro- intestinal tract) are as metabolically expensive as brains, and the gut is the only one of the metabolically expensive organs in the human body that is markedly small in relation to body size. Gut size is highly correlated with diet, and relatively small guts are compatible only with high-quality, easy-to-digest food. The often-cited relationship between diet and relative brain size is more properly viewed as a relationship between relative brain size and relative gut size, the latter being determined by dietary quality. No matter what is selecting for relatively large brains in humans and other primates, they cannot be achieved without a shift to a high-quality diet unless there is a rise in the metabolic rate. Therefore the incorporation of increasingly greater amounts of animal products into the diet was essential in the evolution of the large human brain.

When I ate a high carbohydrate diet (non-calorie-restricted), I felt consistently horrible and could not shake a pound of weight. With a high fat diet, I feel great and the weight is slipping off. I think that is evidence enough for me. The only other way I have lost weight was with a calorie-restricted diet incorporating all foods. Though, I was consistently hungry and had to force myself not to eat. I have not encountered any of those problems eating the paleo way. More people need to rely less on so-called scientists and experts and just do what feels right.

When a well accepted idea is rebutted by someone considered to be a supporter of this idea, people tend to be confused/annoyed. Specially if this person is considered as a guru or an expert on the subject. This is more obvious in the paleo world. As far as I rememember, Stephan never said and/or stated that low carbohydrate is the only way to go. And by the way, I consider Stephan the most knowledgable guy regarding obesity.

This means that I agree with Stephan regarding high carbohydrate diets? No. This means that his apparently "new" ideas are going to change totally my diet and/or view on nutrition? No. What Stephan is saying is that HIS opinion, based on HIS research, is that a carbohydrate oriented diet is better than a fat oriented diet. People need to understand that humans are metabolically very flexible. We are adapted to survive on different types of diets. Everyone will have their own opinion about the perfect diet, but there are only a few people that are 100% convinced that their approach is the way to go. So when someone respected challenges their ideas, they shiver. This happens when you are not completely sure about your ideas and/or dont understand them in the first place. We must have a holistic approach to nutrition. This coming from a huge proponent of ketogenic diets who does not have a problem when someone supports a high carb diet with valid arguments.

I think that "carbohydrate" is the "saturated fat" of the paleo world.

What people miss is that when you switch to a low carb diet, you neccessarily switch to a low sugar, low trans fat/veg oil and low boxed junk food diet.

I went low carb and felt tons better initially. Looking back, it was obviously because I suddenly stopped eating around half or more of my calories in soda, chips, sweetened cereal, candy, cookies, muffins and sweetened yogurt every day.

A few months of high fat/low carb paleo also gave me: muscle loss, fat gain, slow healing, rough/dry hair and skin, insatiable hunger, insanely high cholesterol and hypothyroidism.

To add one more opinion here.... I think that we all like to geek out on foods, macronutrient ratios, insulin, etc. That's why we come onto this site. However, a variety of diets have been shown (eskimos vs. kitavans) to be healthy and allow a generally disease-free life.

Food quality seems to take precedence over everything else, and by that I mean avoiding processed foods and especially sugar, which we can all agree to be detrimental.

I was quite shocked to read his post, however if we're honest (and currently healthy) I don't think it matters what you eat as long as it's real food.

With three points it's difficult to only agree or disagree with him. I'd say points one and two are not wrong. Point three is dependent upon the individual. Some peoe find great satiety from foods that also happen to have large insulin responses. But the big thing many people forget is that THAT'S FINE IF YOUR HEALTHY. I eat white or sweet potatoes with every meal. My insulin probably goes up from that. But that's fine, I'm fit and active. Insulin is in our bodies exactly for that reason!

For point one, again if you're lean and healthy a carb-heavy diet is great! I'm on it, most anyone who is interested in athletic performance is on one. That does not mean grains, it just means carbohydrate. Tubers.

For point two maybe he means our ancestors of more recent generations. Yes during ice ages etc maybe fat and protein were the leaders but I'm sure for 50, 60 thousand or so years tubers have played a huge role. Perhaps outweighing fat. The fat attached to meat yes of course was always eaten but that's it. No olive oils, no macadamia nut oils, no coconut oils. So perhaps carbohydrate played a larger role for a longer time than many pale eaters think.

personally I'll let the numbers speak for theirselves. I know countless people that have lost much weight and felt wonderful doing paleo, that by itself should prove its effectiveness.

Yes, if you interpret paleo as being necessarily high-fat, low-carb, than what Stephan is writing goes against paleo. However, I think there's an emerging consensus among most paleo and paleo-ish writers that a healthy diet need be neither.

There's a difference between saying "Saturated fat is not bad" and "you should consume LOTS of saturated fat". It seems to me some people are getting those things confused. As far as I can tell, no one has ever said that a healthy diet necessarily includes large amounts of saturated fat.

Also keep in mind that Stephan qualifies his statements in several ways. He's saying: IF you're going to be biased toward one macronutrient, it should PROBABLY be carbs.

Let's remember that there's still a lot we don't know, and most of us (certainly myself included) don't really understand most of the science of this stuff- we're just believing what certain people say, and theorizing from our personal experience (often poorly).

My understanding was that we could survive without any carbohydrates. If so, why would a diet which was based on something which was unnecessary to sustain life, be 'probably healthier than a fat based diet' ?

I think that for me,high fat paleo was a corrective diet for years of SAD carb abuse and gut damage.After 3 years high fat I'm over it and I dont feel it's the best choice for long term health.

It goes without saying that Stephan has produced among the most level-headed and thoughtful posts that there are online. That said, the evidence for his "default stance" here is severely limited and so I'm not that worried.

The only argument he offers in support of his suggestion is:

most of our ancestors have probably been eating more carb than fat for a very long time, so my default stance at this point is that if you're going to bias your diet toward a macronutrient, I'd go for carb.

But this doesn't seem terribly convincing. Hunter gatherers have also spent lots of time burning their own body fat and animal protein. That's the metabolic condition that low carb is mimicking (fasting/starvation/winter/calorie restriction). What foods we have eaten is potentially a distraction from what our bodies have actually metabolised. There seem to be a fair few modern studies showing advantages to carbohydrate restriction/ketosis- I think (and have thought for a while, even before this heresy) that Stephan attaches too much weight to what healthy traditions have eaten in recent history. While the high fat proponent has a variety of suggestions to make as to why, at least in certain conditions, restricting carbohydrate and replacing it with fat would be a good idea (in terms of suggested pathways, metabolic effects etc.), I don't know of any comparable reasons to think that biasing your diet towards carbs would be a good idea and fat a bad one. The only suggestions I hear about fat are things about it being highly rewarding (which on its own, it isn't) and containing lots of calories per gram (which if it's important, can be pretty easily rectified).

In any case, Stephan grants that:

Our metabolism is highly attuned to coordinating the appropriate metabolic response to differing carbohydrate-to-fat ratios... cultures have thrived on practically nothing but carbohydrate (New Guinea highlanders, etc.) as well as mostly fat (Inuit, etc).

So I don't think we ought to think that what different cultures have eaten in terms of macronutrient portions (so far as culture-wide generalisations can be made) is likely to be warrant biasing our diet towards one macronutrient or another. I don't think that "The fact that there are so may healthy high-starch cultures, far more than there are high-fat cultures" adds to the "weight of the evidence at all." This may well be more historical accident (for example, more cultures living in warm climates than cold ones in recent times) than a consequence of high carb diets being superior nutritionally (rather than superior for food security, convenience etc.). I also think it's doubtful that there could have been such a preponderance of higher carb eaters over lower carb ones, that we would have since adapted (somewhat losing our flexibility) to be more able to eat high carb diets. The question of adaptation here is also, of course, a loaded one. Maybe we've evolved such that higher carb ratios lead to some advantages (fewer muscle cramps, higher glycogen levels (for running away from predators), easier digestion, higher growth, higher reproduction, higher serotonin levels and so on), whereas long term low carb diets risk the converse disadvantages, but also reduce appetite, reduce weight, reduce cancer, increase longevity. Perhaps we have adapted to have high carb as our historic default- allowing quick recovery, growth, reproduction, shorter life- but still low carb is the diet best suited to our current situation (in the developed world). There might still be reasons to favour a low carb ratio, based on other reasons, however, if it's granted that the humans traditionally eating high carb diets were more active, getting more sun, less stressed, less metabolically damaged, had lower food availability, than we are presently.

The one reason that I do think there is for possibly favouring carbs over fat is that if you eat 85% of your calories from butter or tallow, then you will have basically consumed no micronutrients (apart from lots of vitamin k2). If you eat 85% of your calories from potato, however, you've already met most of your micronutritional needs and gone more than halfway to meeting your protein needs. Of course, it's possible, of course, for low carbists to rectify this situation though, eating low carb vegetables and being selective about what other foods they eat.

Also, although this hasn't been explicitly mentioned, it does seem to be a factor in some people's considerations: I wouldn't attach too much weight to the fact that Stephan remains lean and healthy, despite eating a high carb diet of potato and lentils. Before going paleo, I (aged ~22) lived on mostly wheatgerm and soy milk and I was very lean, very active and so on and lots of my peers are the same, despite getting most of their calories from added sugar. Thus these anecdotal individual cases shouldn't be treated as being particularly indicative.

"I don't think fat is inherently unhealthy, and I don't think saturated fat is unhealthy. I said "if anything" because I think there's still a lot of uncertainty. I'm not condemning fat or high-fat diets. A person can probably be perfectly healthy on a high fat diet if it's designed well. However, I think most of our ancestors have probably been eating more carb than fat for a very long time, so my default stance at this point is that if you're going to bias your diet toward a macronutrient, I'd go for carb." - Stephan from the comments.

Generally accepted ideals according to whom? Since he never claimed to be paleo, his statements don't challenge generally accepted ideals per-se, it depends on perspective. Its fascinating how people will challenge "generally accepted ideals" of the government, delve into paleo, then lock into a new paradigm; questioning leads to change leads to resistance to further questioning.

Stephen's PH.D., his specific study of the neurobiology of body fat regulation, and existing body of respected work probably trump my experience of "well I read MDA, and sent some friends there, and we lost weight with low carb so this is what works and is healthy" as far as developing evidence for what may be the best path going forward.

I'll chose the best evidence every time. Locking into a low-carb paradigm if the best evidence starts showing it to be less ideal than higher carb would be making the same mistake as continuing to follow the old "eat lots of grains cut animal products" in the face of emerging "fats don't harm, grains do" evidence.

Millions of people have lost weight following calorie restricted SAD (and been healthy). Many have gained weight, had weight loss stall, or developed new health problems following low-carb, even with a whole foods approach. These statements are not controversial. Its important to stay open, and see through "what works for you" and "lots of people have followed this and it worked from them" to "this is information from a justifiably highly respected source" if truly looking for the best answer.

http://www.foodtimeline.org/index.html

His post on this topic doesn't seem very clear at all. I know he is a good scientist, but I prefer when writers are more clear and cogent. Maybe Mark Sisson can sum things up in a post using his gifted writing style.

Stephan doesn't distinguish between what kind of carbohydrates, and seems to think that most grains are ok if they are prepared properly, but who has time to traditionally soak and ferment grains? 99% of the wheat you will encounter is not going to be prepared in a traditional manner, even then it is probably a much different kind of wheat than was used a hundred years or three hundred years ago.

Is he talking about carbs from onions, sweet potatoes, yam, taro, beets, etc..?

What about fruit high in fructose like watermelon, mango, bananas?

I'll disagree. Well, at least if I want to be healthy, strong and avoid all of the main points of disease based on an agriculture diet. Though it sounds like he wants to cause contention more than anything else.

1. So what about the masai, or the intuit? I'm not saying I eat that way with those specifics in terms of ratios, but they avoided the perils of civilization based diseases with a high fat/moderate protein diet.

2. I think there is a case for a possibility of a high-carb diet being okay, but it's definitely not based around grains. Tubers or rice would be about the only two I would consider (at least in my case). I just think that the rising rates of celiac disease in Italy showcase that our grain based society is going to work long term (not to mention the ridiculous amount of obesity in America).

3. Um, why? Spiking insulin is bad. It causes fat storage. I don't want fat storage! Worst of all, they cause me to be hungry. If I eat a high fat/moderate protein/moderate-to-low carb (low on glycemic index) I'm at least not hungry. Reduce insulin levels, restore proper leptin balance, and ignore the foods that have been genetically modified to be super sweet.

It's all good stuff for discussion.

As many have pointed out, there exist examples of whole peoples thriving on higher-carb such as the Kitavans. I don't doubt this for a second. Of course they didn't/don't consume grains or any appreciable amount of refined sugars. The thing for me though, is that the evidence which shows that other cultures thrived with practically zero carbs is also compelling. (Ie: Inuit).

I just feel that any kind of carb is simply not necessary. To me they are fillers. I do eat vegetables and nuts so that I don't look 'weird'. (I cut out milk, but not cheese and heavy cream, but am sad to say they will most likely have to go as I do believe I am still having problems with them. BOO!) I think that potatoes and root vegetables are fine and won't cause harm, so I don't mind eating those if I feel so inclined. (I just don't have a craving for them).

I do agree that grains, soy, corn and legumes and of course sugar are complete JUNK! *Note: Soaking and fermenting grains is a complete waste of time, and honestly tastes like crap. I rather eat refined white bread b/c it at least 'tastes' good. (I don't, b/c I stay away from gluten). Same goes for rice. Why bother with 'brown rice'? It tastes like card-board!

Finally, despite using a flawed logic here, saying "Well, for me personally," I am quite content eating a high-fat, moderate protein, and low carb diet for these reasons:

a) major digestive issues b) improved health of my skin (this is why I will have to give up cheese and cream? Despite improvements in dryness, I still have a rash that's not going away). c) More energy: As a person who trains in karate, I have noticed an INCREASE in endurance. I don't feel that panting out of breath, hunching over b/c I feel so winded.
d) I believe in the proponents on neurological health that is remedied by ketogenic diets. (I personally don't suffer from epilepsy or anything like that, but I feel like such a diet helps with overall brain function; no more mental fog, no headaches etc). d) As a woman, greatly reduced PMS, as well as better health during menstral cycle. e) Satiety/enjoy the foods I'm eating. I actually enjoy what I'm eating for the first time in my life. I don't feel 'starving' all the time, which is nice.

*Note: Weight-loss has nothing to do with this. You could consider me one of those 'eat anything and not get fat'. But honestly, at what price? I just prefer feeling good. It gets old real fast 'bragging' that you can eat x amount of chips, pop and ice cream. (Er, rather other people would always comment to me instead of me 'bragging'). *I'm not saying that I lived on chips, pop and candy. A typical day would have been: bagal w/ slathered butter or cream cheese: sometimes eggs, bacon and toast: or generic cereal. Lunch would be jamaican patty, or chicken burger of course with bread/bun. Dinner would have been chicken/beef/pork/fish, rice/potatoes, and some type of veggies. For beverages I drank water, milk, sometimes mango juice, sometimes coconut water. I would have desserts sometimes such as ice cream, some type of pie or cake etc. I really don't think this is that extraordinary compared to what a lot of people eat. Yet I was experiencing all kinds of problems. What? But hey, I was slim right? I worked out right? Of COURSE I was healthy...NOT! *Btw, I'm only mid-20s...

Anyways, what was supposed to be a quick post turned out to be a 'thesis'. I've given more than my 2¢, so I'm off and everyone enjoy the foods that they feel most comfortable eating!

p.s. I honestly didn't enjoy eating before. It felt like a chore, yet I felt addicted to certain foods (yet didn't feel like eating at the same time, weird). *I was addicted to pop for about a year, but forced myself to stop. This was several months before switching to high-fat etc. Mostly I ate because I felt I had to, to get nutrients and the fact I didn't want to be anorexic or anything like that. I enjoy eating now! The food tastes wonderful! I don't feel addicted and when I'm full, I don't feel physical discomfort.