So, you know i lurve me some science. I do not like science in sciencey words, tho – I likes it nice and simple. I guess because of the buzz about the K-E Diet (/shudders), I have wound up having several conversations recently about exactly what is ketosis and why does it work. Here is Kitteh’s best understanding. (Kitteh iz no doctor! Proceed at own risk!)
First, like all srs students, let’s start with what Wiki has to say:
If the diet is changed from a highly glycemic diet to a diet that does not provide sufficient carbohydrate to replenish glycogen stores, the body goes through a set of stages to enter ketosis. During the initial stages of this process, blood glucose levels are maintained through gluconeogenesis, and the adult brain does not burn ketones. However, the brain makes immediate use of ketones for lipid synthesis in the brain. After about 48 hours of this process, the brain starts burning ketones in order to more directly use the energy from the fat stores that are being depended upon, and to reserve the glucose only for its absolute needs, thus avoiding the depletion of the body’s protein store in the muscles.
Now, that’s the best and most succinctly I have ever seen it put. But let’s break it down now, in less sciencey, more kitteh friendly words:
1. When you stop giving your body an abundance of carbohydrates, your brain has an problem. It needs glucose, a.k.a. “blood sugar,” to do its brainy thang. So at first, it keeps up your blood sugar by “gluconeogenesis” (look at that word – gluco (sugar) neo (new) genesis (making) – making new blood sugar) by basically converting the foods that you ARE eating (fat and protein) into blood sugar.
2. Gluconeogensis is not only hard to say, it is also verra hard to do and metabolically expensive – meaning, it costs your body precious calories to convert protein or fat into glucose. So it looks for a better solution. That solution is KETOSIS. But before we get to the bliss of ketosis, let’s observe that this period is NO FUN. During this period, your body/brain is still looking for the “easy” hit of fuel from carbs, like it is used to, so it sends “I AM STARVIN, GIMME CARBS YOU FOOL!” signals to your entire kitteh being. This is what I call “coming off carbs” and it SUCKS PROFOUNDLY.
3. After about 3 to 7 days (depending on a lot of factors, but including how strict you are) of STRICT low carbing, your body makes the switch. (Not coincidently, that’s why so many of the low carb plans have an “induction” phase, in which the carbs are kept lower than the rest of the time you are on the diet – to kick you quickly over this hump.) While you are in gluconeogensis, you may have what is called the “fog” or “low carb flu” as your body complains and tries to talk you into giving it easy energy.
Nirvana ketosis happens when your brain figures out you ain’t gonna cave and give it carbs, and it needs a new strategery. Instead of clumsily turning fat into sugar (blood sugar, that is), it simply changes over and starts burning fat for fuel. That works great – some say better than carbs for brain fuel – but there is a TEEENSY little problem. The brain can use a PART of the fatty acid chain of fats, but not all of it. Like a third of it or something can’t actually pass the “blood brain barrier” to be burned. So what does the clever brain do? It strips the fatty acid chain apart, like hulling a nut or shucking corn, takes the tasty bit it can use, and -petooey – spits out the rest.
5. So what happens to the rest? Well, the brain had to tell the body to burn it (get it off your arse, for instance) to get the little tidbit it needed, but the part it can’t use won’t be burned up before the brain needs another tidbit. So the extra, which are called KETONE BODIES, are just expelled through the body… through the breath and urine, mostly, but to some degree just through the skin/sweat. Ketone bodies are harmless, but smell like acetone (the stuff in paint thinner and nail polish remover).That’s why people in deep ketosis may smell yucky (especially in their breath) and why my pee smells like a bottle of nail polish remover at the moment. 😉
6. Once that switch is made, the body doesn’t NEED carbs anymore (meaning, it stops screaming for them all the time – not debating how much carb is “needed” for healthy processes). And when it does get them in moderation, it stores the resulting glucose in the muscles and kidneys for emergencies – which is why you can have SOME carbs but not too many or you kick yourself out of ketosis.
7. Using up the tidbits and spitting out the rest is why you get rapid weight loss in ketosis – you aren’t having to actually “use up” (burn off) all the stored energy in each pound of fat, rather, part of it is discarded in the form of ketones.
Side effects include stinky breath/weird taste in mouth (which I address with occasional sugar free cinnamon gum), stinky pee (which I live with and even kind of welcome as a sign I am burning away at my fat stores!) and sometimes restless sleep for a few nights when you convert over.
For me, I can TASTE it but have rarely smelled it on my breath, but some days for whatever reason, I will feel like I REEK of it. I have a sensitive nose, though, so I don’t know that anyone else can notice it, except possibly those close enough to kiss you. 🙂
Oh – and THIS is why (IMNSHO) it kills a lot of us to go on and off of low carb – once you made that switch, tell yourself it is STUPID to go back through the whole process again.
And oh! again – if you do NOT put yourself in ketosis, you will still burn fat. But you will do it the old fashioned way of “after you have burned up all the other available energy forms” because your body/brain isn’t set up to burn it, it is “least favorite fuel” when you are in high glycemic (high carb) mode.
Last bit: the EASIEST fuel to burn for the body is… alcohol. So if you drink, that will get used up before your body burns anything else off, whether “else” = stored fat or “else” = food you just ate. Once you are in ketosis, the order becomes: alcohol, fat until you kick it out of ketosis by giving it a dose of carb. But OUT of ketosis, you will burn first any alcohol, then any carbs you have consumed, then any fat you have consumed, THEN stored body fat.