The only people who need carbs are people who evoke a per/minute calorie demand that fat can't supply alone (fat can't really supply more than 15 cals/minute). This was the evolutionary purpose of glycogen stores (and why we store so little, relatively) - to kick in when we have to haul ass for several minutes and fat alone can't prpovide the rate (not quantity) of calories. The only people fit enough to achieve these calorie demand rates for long enough periods of time to burn through glycogen that needs to be replaced with more than just vegetables are elite/sub-elite enduranc athletes - sports that already pre-select for insulin-sensitive ectomorphs. Sure, regular fit folks burn a little bit of glycogen, but it can be replaced with surprisingly little carb intake. Even elite endurance athletes aren't burning more than maybe 600 cals a day in glycogen with training sessions that burn 1200+ calories.

The reason why carb calories turn to fat so easily (once glycogen is topped off) is because non-agriculoural carb sources that are useable without cooking are largely seasonal in a paleolithic environment - you get a huge haul of carbs during fruiting seasons, and then none. So it is evolutionarily advantageous in a hunter-gatherer environment to be able to turn carbs to fat quickly. Hunter-gatherers had a steady, but small, supply of carbs the remainder of the year. Evolution would have selected for people that can turn those seasonal hauls of calories into fat easily. Doesn't work so well in the modern environment.

The interesting question is how much has the genome changed owing to agriculture that makes some groups and some people within groups remarkeable adapted to agriculture and more insulin sensitive and others not and how can that change across the life-span.

When I began eating low carb, one of my coworkers implored me to reconsider, insisting that the diet was unhealthy, that the brain needs the sugar. This "expert" advice came from a woman that was morbidly obese and had just been denied medical clearance for a gastric bypass.

Fact is, after nearly 3 years, I can no longer tolerate sugar, gives me a headache and the shakes within minutes.

I love how high-carb folks will say something like "the brain needs sugar" to justify carb intakes of 50%+ of macronutrient calories.

I am a 80 mpw distance runner and stopped with the high carb stuff about a year ago and my performances don't suffer at all. I eat just enough carbs to replace glycogen stores (maybe 600 cals on a 3000+ cal a day diet)- no point in any more. I was always lean on higher carb too, but I have more energy now, feel a lot warmer in cold weather, and I never really liked pasta that much anyway. My carbs are now yams, fruit, and sometimes calibrated servings of white rice (ala Mark Sisson and Cordain's reommendation for athletes). I eat wheat on a rare cheat day to not be a pain to guests.

Amy, if you read the comments, in addition to bacon, another "bad"(allegedly) food I discovered I really like that I wouldn't have touched pre-Cordain is brats! Who knew! The Guinness brand is great.

How timely,. I gave up sugar, just that, and did not change my diet in anyother way and since Sept. 22 I have gone from 279 to 253 lbs. as of this morning. 26 lbs down with not much exercise, and eating lots of meat and veggies. today, I will have 2-3 small candy bars and cake after our holiday meal. I Feel Great

I love it (not) when online health advisors say so patronizingly that type 2 diabetes is *not* caused by eating too many sweets. It's just...a mystery!

It seems pretty clear now that it can be, and is causing type 2, a lot. It just doesn't happen overnight but after years and years of carb abuse.

Thanks, must mention the oatmeal and bacon that helped my do it

It isn't low carbs that is bad, that is actually very good. What is freakishly unhealthy and causes bad reactions is when people go on ZERO carb diets and ZERO sugar. The zero is replaced with eating more bad stuff and sugar replacements to keep things sweet.

I have (comparatively) very low sugar intake and I am healthier for it though my food intake is massive just to stay above under-weight which makes me tired and prone to illness.

The brain does need glucose. Some lowcarbers say you can get used to fueling yourself on ketones, but I prefer to have a productive day.

If you eat enough protein, your body will make all the glucose that you need via gluconeogenesis.

Quit carbs three and a half months ago because my cholesterol was high, and my fasting blood sugar was 103 (I know, not really that high but they put a fucking asterisk next to it for being three points over).Most days it was a bacon and mushroom omelet for brekkie and a venison patty for dinner topped with sour cream, guacamole and pico de gallo. My cholesterol went from 251 to 189 in that short time, took no pills.

Had a patient at the hospital whose fasting blood sugar was 535. His triglycerides were 2883 (not a typo, 2883) The doctor was stunned, told the patient he shouldn't even be ALIVE. Patient walked out AMA because we wouldn't let him eat what he wanted.