I think the community's general failure to acknowledge a dichotomy inherent within the term "carb" is to blame, but that failure isn't anyone's fault, just that most people don't know a whole lot about science. You can read and understand plenty about core Paleo premises -- insulin sensitivity, gluconeogenesis, fasting, fatty acid oxidation, etc. -- without ever learning a thing about basic biology, that a "carb" isn't a thing, it's a class of things, and that not every member of the class has the same biological activities. Again, most people aren't intimately familiar with that fact, basic as it is, unless they've really delved.

Case in point: glucose versus fructose and the dichotomy you pointed out flying under the radar of a lot of Paleos. Glucose hardly stimulates de novo lipogenesis (production of fatty acids from a Krebs intermediate) yet incurs an insulin response while fructose powerfully activates de novo lipogenesis yet elicits no insulin response. You and I have both seen people unknowingly create some Frankenstein chimera carb that both skyrockets insulin and forces you to pack on the fat and raise serum TGs. Although sucrose could certainly do that, most wouldn't make the distinction and tend to chalk up carbs as the end-all "nutrient" for health, longevity, and leanness. This, I think, is an innocent example of the blind leading the blind, of well-meaning hearsay from those who just didn't know the difference.

This site exists, and questions like this exist, to make the bottom-line information for most people with a loose familiarity with science as accurate and simple as possible. Until that goal is accomplished, minor details like these with major implications will misrepresent essential truths about the body's biochemistry, and many people will take with the bank to them incomplete, inaccurate, and possibly counterproductive knowledge. We just have to catch those little falsehoods when we can and set the record straight.

"Carbs" are not the enemy, but excess glucose, and fructose and sucrose especially, are, all for different reasons.

Becker, you're onto something here. After succeeding on a low-carb diet, I became convinced that the lower the carbs, the better. Now, I know better. It's the food toxins: gluten, refined carbs, casein, fructose, etc. Reading the PHD, Masterjohn and Guyenet definitely freed me from this thinking.

There is ample evidence that humans evovled eating a variety of diets: ketogenic, VLC to very high carb. Yet these people were all healthy. Why? It's the absence of gluten, excess sugar (fructose). The Kitavans, Okinawans, Southeast Asians. They all lived on a carb-heavy diet. Sweet potatoes were the staple of the diet for these people: for post-War Japan, the Okinawans ate up to 85% of their daily calories from carbs. Check out this link which shows how high their carb consumption was, and how little fish they actually ate (less than 1/4th the mainland Japanese). Yet they produced more centenarians than any other ethnic group.

http://fanaticcook.blogspot.com/2010/07/traditional-okinawan-diet-sweet.html

The Southeast Asians ate heavy white rice but stayed healthy, as long as they did not consume sugar (fructose) or gluten. The mainland Japanese were for the most part healthy, too, though not as healthy as those in Okinawa.

Yes, the Inuits were healthy, too. The only carb source for them would have been liver! And perhaps whatever they could have dug out under the Tundra. But there is strong evidence that those who consumed lots of carbs stayed healthy, as long as they were starches devoid of sugar and gluten.

That, really, is the next big distinction the Paleo and Low Carb crowd have to make. Yes, if you have diabetes, you probably cannot tolerate starches and Low Carbing is probably the way. If you're not however, it is perfectly healthy to avoid the bad and embrace the good carbs.

Someone who is exercising needs about 150g of carbohydrate a day and they will get it whether it be exogenous or endogenous. Low carb diets actually tend to be lower carb than reported because gut bacteria tends to eat the bits of carbs from non-starchy vegetables, this means even more gluconeogenesis will be going on. If they are insulin-resistant and shit be screwing up and making tons of glucose out of amino acids and glycerol they can very well have higher triglycerides without all that much carbohydrate. Whereas someone eating that much and generally metabolically healthy (you, obviously) might even see improvements by resolving nutrient-deficiencies and some other mechanisms. Apparently (although I'm not sold yet) tons of gluconeogenesis can increase cortisol levels, which causes insulin resistance. That's my guess.

I like about 150g of carbs per day combined with IFing to get into ketosis twice a week, but I think that unless someone was super active they're generally going to store a lot of carbohydrate as fat if their carb intake is higher. Indeed, 30% carbohydrate isn't really a problem. The problem is higher carbohydrate intake (60% +), poor metabolic health and inactivity.

you should be a bit clearer on what you mean by "starchy" carbs. there's a difference between starchy veggies and grains.

but i will agree whole heartedly that sucrose(sugar) and HFCS are the culprits of many many things that where once thought caused by fats, for example.

fructose from fruit is different than just fructose because of the fiber in fruit, pulp and skin.

thanks for sharing your finds. i still won't eat potatoes, corn or sweet potatoes and grains don't exist for me.