Hello and welcome to another beautiful day in the thrilling KETOSIS saga. I’ll be honest in telling you that I really enjoy this subject, and I see that a lot of you are interested in learning more as well. Yesterday we learned about the different types of fuel our body uses during aerobic and anaerobic exercise. Today I thought I would discuss what happens to us hormonally during aerobic and anaerobic exercise, and how these hormones interact with the different types of fuel our body uses during training. From there we will begin to see more clearly what choices we have in our diet to best facilitate the results that we wish to achieve. After tomorrow’s post I’ll put this all together for you. Following The Sunday Quickie, on Monday I’ll explain the method that I’ve decided upon using, and the specific approach I’m taking to get what I believe to be the most from my training and diet. Right now let’s continue to look at some more of the factors involved in this decision.
As you already know there are two types of training we are looking at, aerobic and anaerobic. Let’s begin with what happens in your body hormonally when you are doing aerobic exercise, which typically involves running or cycling or anything that is done continuously. As I said yesterday, depending on the pace and duration of the circuits you perform, or whether your sprinting is continuous with slower running or cycling during the non sprint portion, if it is anything like mine then it falls into the category of both aerobic and anaerobic training. On a side note I consider this to be the most effective way to train for fat loss and muscle building at the same time, but that’s not what this article is about. At least not directly.
When engaged in aerobic exercise, the most notable change that you don’t need a microscope to observe is the increase in heart rate. There is an awful lot that is also happening other than your heart pumping faster to get more oxygen to your muscles, as well as to facilitate the removal of exercise bi products like lactic acid so that you can train effectively and efficiently. Lipolysis, meaning in basic terms the liberation of fat to free fatty acids into the bloodstream to be used as fuel, also accelerates to provide some of the necessary energy. The other source of energy that will be used is glycogen, as both liver and muscle glycogen breakdown have begun to speed along up well.
The lower the level of intensity used in the exercise, the higher the rate of fat that will be broken down to be used for fuel. The higher the rate of intensity means that the ratio of fat will be considerably lower as the body will opt to use the quickest source of fuel available, which is glycogen. This fact is the basis for the long standing belief that the best way to lose body fat is doing steady state cardio at a slow pace. To this day, most bodybuilders preparing for a competition use this method and for them it is effective. I am in now way passing judgment by saying this next comment, but most bodybuilders don’t have to consider the hormonal response needed to induce fat loss as their needs will be met by using various exogenous sources. For their purposes, long and slow cardio will be effective. For the rest of us it may not be the most effective method as there are other factors to consider than just the fat loss aspect as this type of cardio also raises cortisol, which is detrimental to muscle.
Further enhancing the body’s ability to liberate fat to use for fuel is a corresponding drop in insulin levels during aerobic exercise. When insulin is present, the body is in storage mode, so in order for fat to be released the levels must be very low. Much like the fat and glycogen ratio, there is an insulin and glucagon ratio. Glucagon is the catabolic counterpart to insulin. Insulin encourages growth, and glucagon for our purposes breaks fat down to be used as energy. As the insulin level drops, the glucagon level will rise, further enhancing the release of fatty free acids into the bloodstream.
There are some conclusions that we can draw from seeing what the source of energy is being used during both a high and low intensity of aerobic exercise, and how this would interact with a ketogenic diet. When in ketosis, there is little in the way of glycogen available to be used as energy. That means that intense aerobic training would not be ideal, as the needs for glycogen will be met through the breakdown of muscle tissue known as gluconeogenesis. This is obviously not very good when the goal is to retain or build muscle at the same time as lowering body fat levels.
Conversely, if fat loss is your only concern, then doing cardio at a low intensity for a longer duration while in ketosis will prove to be very effective. If by doing your cardio at a low intensity, then the ratio of fat versus glycogen being utilized for fuel will be at its highest. The need for your body to catabolize it’s own tissue to provide glycogen will be lower as well, meaning you will retain muscle better. Due to the already extremely low levels of insulin as a result of being in ketosis, the level of glucagon will be extremely high, and all of these factors will work in unison to make fat liberation and utilization extremely effective. On a personal note, I know this to be true anecdotally.
To take this one step further, even if you are not following the ketogenic diet protocol, there is still a way of using ketosis to your advantage when engaging in aerobic training at a low intensity. After an overnight fast the body will either be close to, or in a mild state of ketosis after going the entire sleeping period without fuel. If fat loss is the main goal, then fasted cardiovascular exercise can be very useful here. Ketones appear in the blood after aerobic exercise as a general rule, so coupled with an overnight fast even an individual not in ketosis will be able to produce and use ketones for fuel. This is the basic principle that suggests that fasted cardio is the most effective form of training for fat loss. As I stated earlier, there is a corresponding spike in cortisol levels as well, so as with all things involving the body there is a fine balance that needs to be found.
Two very potent hormones that have not yet been discussed in the context of aerobic training are testosterone and human growth hormone. The best way to release the two of these hormones when training aerobically is through high intensity exercise such as continuous sprints or continuous circuits that will both be exceeding the lactic threshold. This means that the energy source that will be most relied upon will be glycogen. Where there is lactic acid however, there is growth hormone and testosterone shortly to follow. Both of these hormones play an important role in fat loss, but as you can see in order to have them released there will need to be glycogen used to fuel the process. Meaning that if you’re in ketosis and attempting this type of training to elicit this hormonal response, then it will be at the expense of your muscle tissue to do so. During protein resynthesis much of this will be replaced, but this is not a great recipe for muscle growth.
As is the case, independent of testosterone and growth hormone release, there is still a unique benefit that can be achieved biologically, hormonally and through a ketogenic diet, that will enhance lipolysis and therefore fat loss. To be honest I hadn’t even really put this together in my own mind until I began writing about this, and followed the trails of evidence to this conclusion. It has given me pause to reflect upon a few traditional diet techniques, and how they too can be improved upon. Tomorrow I will get into the hormones produced during anaerobic exercise, or weight training for our purposes, and how they interact within the ketosis induced environment to see what advantages can be found. The funny thing is that this was supposed to be just one article, but with ketosis there is always so much more to discover. Until tomorrow then,