June
2008
Dear Mark: Ketosis
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Ketosis Killers
Dear Mark,
What are ketones? How does ketosis play into the Primal Blueprint? Did our bodies evolve to run on ketones? If not, why do they exist?
Ketones, to put it briefly, are compounds created by the body when it burns fat stores for energy. When you consume a diet very low in carbohydrates, the body responds to the significantly lowered levels of blood sugar by flipping the switch to another power source. The body converts fatty acids in the liver to ketones. Ketones, then, become the main energy source as long as blood sugar levels remain low.
Recently, researchers have discovered more about the unique mechanisms behind this energy “switch.” It turns out a specific liver hormone, FGF21, is essential for the oxidation of the liver’s fatty acids. Furthermore, animals who were fed a ketogenic diet over time showed “increased expression of genes in fatty acid oxidation pathways and reduction in lipid synthesis pathways.” In other words, their bodies adapted metabolically and genetically to the diet.
Ketosis was crucial to our evolution. Given the relatively minor role of carbohydrate-rich foods (even the consumption of many tubers is thought to have come later with the advent of cooking practices), our bodies were fairly frequently operating in the arena of ketosis. Add to this the fasts and famines of primal living, and it’s clear that ketones served as an essential energy source.
The Primal Blueprint recommends “generally” about 100-150 grams of carbohydrates a day, but many who follow it or the related paleo principles choose diets that fall in the realm of 50-80 grams a day, a practice (along with IF) that spurs the body to turn on ketosis as needed. These practices encourage “upregulation” of the body’s fat-burning metabolic functioning and “down regulation” of fat storing systems. For those looking to lose fat, this becomes an extremely effective tool. On the other hand, after spending a few days or weeks in a predominantly ketosis mode, it may behoove you to do an occasional higher carb day (maybe 250-300 grams) to simply readjust insulin sensitivity. This is particularly appropriate if you have achieved an ideal body composition (lean body mass and body fat) and don’t need to lose more fat. An essential part of the Primal Blueprint includes both the fat-burning upregulation and the periodic honing of the body’s systems and adaptive responses.
Finally, ketogenic diets, which are generally lumped together by critics, have gotten a lot of bad press. While experts have generally recognized their effectiveness for weight loss, very low carb diets that result in ketosis (like the Atkins) have been criticized on health grounds. The problem with these criticisms? They’re based on diets that allow for 20 grams or less of carbohydrates a day. While I believe we are not meant to run primarily on carbohydrate energy, I do believe we depend on the nutrients offered by low carb vegetables and even some low glycemic fruits. A diet of 20 carbohydrate grams simply can’t allow for the plentiful intake of nutrient-rich vegetables.
When your carb intake is low enough, say 50-80 grams a day, ketosis kicks in when it needs to. Over time, this process becomes efficient as the body “unfolds” in its genetic expression. Yet this carb intake is high enough that you can freely include copious amounts of nutrient- (including potassium) rich vegetables to offer the body sufficient nutrition, fiber, and alkalizing minerals. At 100-150 grams a day, again all from just veggies and fruits, you probably won’t hit ketosis, but you also won’t prompt a rise in insulin or fat storage.
Thanks, as always, for your questions. Look for more on low carb living this week. In the meantime, keep the questions and suggestions coming!
insearchofbalance Flickr Photo (CC)
Further Reading:
The Definitive Guide to Grains
What Happens to Your Body When… You CARB BINGE?
Act “As If” - A 30-Day Primal Health Challenge
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That was a great post i never herd it explained in that way.
Sounds like the ultimate “hybrid” fuel technology, doesn’t it?
I hear and read lots of “expert” opinion that the brain needs a lot of glucose to operate properly, yet pediatric neurosurgeon Dr. Larry McCleary (& other neuro-scientists) indicate that the brain can use ketones for fuel, too. www dot drmccleary dot com
Great post,
but could you just elaborate more on what exactly do I expect of my pancreas to do? thanks in advance 
I quite don’t get this “carb up day once in a while to readjust insulin sensitvity”. Sounds tempting for a low carber to be allowed to order a pizza w/ a beer every other week
Hi.
Like zbiggy, I’m interested in exactly what you mean by the “carb up day”. I am most definitely insulin resistant (since I was 9years old) and I have been low carbing since 2003. I went off-plan for about a year, gained some back, and am now on plan seriously for the duration. I tend to get cravings from eating starch/sugar so I don’t allow them at all. Do you mean “carb up” with more low glycemic veggies/fruits or actual starches/sugars?
Hey, Mark. All this low-carb and fasting got me thinking: Is it possible to be a pro, or a semi-pro athlete and still run on 100-150g of carbs with a couple of fasts per week? I have done a lot of experiments on myself with switching from high carb to low-carb&high-fat but… I never ever managed to have a good workout followed by a normal recovery with fasting. When I say good workout, I mean 1.5 hours of wrestling or weightlifting or gymnastics. Ofcourse, I have to be partially recovered for the workout the next day. If I don’t eat anything 3 hours after my post-workout meal (25g of protein and 70g of carbs from dried berries or pure glucose) I’m a wreck the next day. If I don’t eat my breakfast, the same thing happens. I won’t even start about the days when I have two workouts.
So… How about a little sport-tuned Paleo diet? (Does it then become the Zone diet?)
P. S. Sorry about my English, I’m from Croatia.
whole fruit and veg are nice and nutritious - and that’s why i eat them - but they are not unnecessary - organic outdoor naturally reared liver, eggs and whole dairy will provide almost all your mineral and vitamin needs in abundance, along with protein and fat. The only issue is vitamin c, and on a low carb diet you only need a fraction of the RDA. so a little fruit goes a long way
m
markus,
I think you are probably right about that, but hardly anyone eats liver anymore, let alone from animals naturally raised on pasture. Now that I have some non-factory farmed source of liver, I’m trying to cultivate an appreciation for it, abut it isn’t happening overnight and especially for beef liver, requires a lot of mustard or other distraction.
I was very interested to learn how sugar and Vit C compete for uptake in the cell and that a high sugar/grain diet is probably what caused scurvy on the long distance European exploration ships, not so much lack of Vit C. Those crew sailors lived on a high glucose diet of hard tack (dried flat bread), molasses, jams, and only bits of dried meat/fish - non-perishables mainly and very little fresh food (I think the captain and officers had better fare). Eventually some provisions included barrels of sauerkraut, which would have displaced some of the high glucose foods as well as provided extra Vit C to compete for uptake. And of course limes were added to the British navy’s rations.
Zoran,
It’s probably impossible to compete as a pro athlete - or even a top age-grouper - on only 150 grams carbs a day…unless your events last less than 45 minutes and you train hard for less than 45 a day. I guess I will have to do a post just for the athletes who want to be “primal” but also want to train incessantly long and hard.
Maya, zbiggy,
I do mean to “carb up slightly” with some healthier choices, like yams, sweet potatoes, berries, fruits etc. Only to 250-300 grams total for that day and only once in a while (not the 1000 grams that some body-builder sites suggest for “mass”). It would mimic a day Grok found a stash of tubers or honey. That little added carb-up simply has your pancreas secreting a bit more insulin for that day, which is OK if you haven’t been secreting much for a few weeks. If you are coming off years of insulin insensitivity, it might make sense to stay “primal” for a few months before experimenting with a slightly higher carb day. OTOH, if you were to never “carb-up” you’d be fine - it’s just that we want to try to mimic the non-linear, feast-or-famine style of Grok in a more controlled fashion.