I found this on reddit I thought it was a great summary of how ketogenic eating works. By re76 How Keto Works It is common knowledge that weight loss can be expressed as a function of calories in vs. calories out. Eat too many calories and you store fat, eat less calories and you burn fat. This is a true statement in general but the one thing to keep in mind is that this is a gross simplification of how the body works. There are actually many other factors at play. In order to expand on these other factors we first need to understand how the body works in a typical scenario. The body has many ways to store energy, but two of the most common are glycogen and ketones. Glycogen is formed from carbohydrates, while ketones are derived from fat. The body prefers glycogen because it requires less energy to make, this is sort of a path of least resistance scenario. When we ingest carbs, they immediately get turned into glucose and the body does one of three things (maybe four) with them: If our blood glucose is low, they will immediately be used in order to increase the blood glucose level. If our blood glucose is normal, but our glycogen reserves are not at capacity, it will convert the glucose into glycogen, which is stored in the liver, and partly the muscle, for later use. If our blood glucose is normal, and our glycogen reserves are full, the glucose is converted into a triglyceride which is then stored in fat tissue. If our blood glucose is high, you are either insulin resistant or your pancreas is not functioning properly. You have bigger problems. This whole process is regulated by our pancreas, which secretes two hormones, insulin and glucagon. Insulin signals the body to reduce the blood glucose level by telling adipose fat tissue to take in the extra blood glucose and store it away as fat. Glucagon signals the body to increase blood glucose level by telling the liver to release glucose into the bloodstream (glycogen is what it uses to make the glucose). The problem with eating a carbohydrate rich diet is that we are constantly adding a bunch of glucose into our system, which is then causing insulin spikes to try and tame our rapidly skyrocketing blood glucose level. Unless we have depleted our glycogen reserves this insulin response causes the glucose to be immediately stored as fat. Even more scary though is if we keep doing this long enough, there is a possibility to develop an insulin resistance. Now you are pre-diabetic. This repetitive spiking of insulin any time we eat, causes us to almost always have an elevated level of insulin. The elevated level of insulin actually prevents us from converting fat into energy, because the insulin is signaling the body to do the exact opposite. This is why on a carbohydrate heavy diet, you become lethargic and sleepy if you dont eat.Your body is so reliant on a constant stream of glucose that you become very inefficient at actually converting stored fat back into a usable form of energy. So how do we break this cycle and get our body back on track? Eat fewer carbs. So now that we understand how the glucose pathway (glycolosis), lets discuss the less known, and less used ketone pathway (ketogenesis). So if you think back to biology you might remember things called mitochondria, the citric acid cycle, and ATP. Basically mitochondria use the citric acid cycle and an input, either Pyruvate which is derived from glucose, or Acetly-CoA which is a ketone body. They both can be used to create ATP, the energy of our body, but they come from very different pathways. Ketone bodies are produced when the body is depleted of carbohydrate stores such as glycogen, and there is a low level of blood glucose. When our body gets to this point it realizes it needs some way to create energy (ATP), but it has to start using a secondary method of getting ATP. This is where ketogenesis comes into play. The body can use Acetyl-CoA which is a ketone, to fuel the citric acid cycle. At this point you might be wondering how does the body manage to maintain a safe blood glucose level? When in ketosis the blood glucose level is maintained through a process called gluconeogenesis. Gluconeogenesis is a process by which the body can generate glucose from fatty-acids. The fatty acids are provided by our diet, and fat stores (love handles). So by not eating carbs we are forcing our body to derive glucose and ATP from forms of fat. All the while because we are not bombarding our metabolism with glucose from carbs, we have a very small, and very stable amount of insulin in our systems. If you remember back to what Insulin does, it effectively tells our body to pull glucose out of the blood stream and store it; so with low-stable insulin levels this means we have very small opportunity to store fat while in ketosis. Another benefit of being in ketosis is now our ketone pathway is firing on all cylinders, and there is no insulin to hinder retrieval of fatty acids from fat stores, we are able to very efficiently create energy from the fat stores that we have. This is why intermittent fasting is such a great compliment to keto. This is also where the clean-energy feeling comes from. Even if we go for 12+ hours without eating, it is possible to not feel sleepy or lethargic while in ketosis because the body has a readily available supply of fat that it can pump into the ketone pathway. There are also many other benefits of intermittent fasting such as autophagy, which is a process the body uses to do house cleaning, basically the body recycles dysfunctional cells. I set out to just outline WHY keto is good, but I ended up writing a full discourse on HOW it is good. To summarize the main benefits of keto are: It manipulates your metabolism to a state where converting fat into energy is extremely easy. It regulates insulin production, and prevents or even corrects, insulin resistance. It provides very consistent and clean energy levels by stabilizing insulin production, and promoting use of fat stores as energy in periods of fasting. So even though it is possible to lose weight using a normal calorie-restricted approach, the keto approach is much more conducive to weight loss, because it promotes the burning of fat as energy. It also allows you to eat more calories because the ketone pathway is overall less efficient than the glucose pathway, in terms of ATP/calorie, this goes back to the path of least resistance thing.
Posted on: Mon, 04 Aug 2014 14:47:25 +0000
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