Over the past couple months, I have spent a significant amount of time doing some intense research in the UT lab on Intermittent fasting. As such, I have learned a lot and realized how little I actually knew/know about nutrition and metabolism. Since it is my responsibility to provide the most current, up-to-date information to all of you, I am going to be editing a number of my previous articles/blogs on nutrition, especially those including information on intermittent fasting. Since some of the information may be inconsistent, I will be removing the bad information and replacing it with more current information and more optimal ways to implement it in your life.
As science and research grows, I will grow along with it. I hope that you as the reader understand that my previous work was based on what I believed to be the most up to date information. I am not infallible and sometimes my information may be inconsistent. However, rest assured, I am committed to bringing you information that is backed by science and can bring you results. What follows is the first of many articles that I edited to include the most up to date information. In the very near future, I plan to fully update all of my information regarding intermittent fasting as that Is my primary field of interest. Again, I appreciate all of you. Please do not hesitate to ask any and all questions.
Reader Q & A: Should I shift my carbs to training days while intermittent fasting?
"So I intermittent fast, and I generally workout Thursday-Sunday due to my school schedule. So my question is, since I am also in a calorie deficit, should I reallocate my carbs to be less on Monday-Wednesday and increase them on Thursday-Sunday, or have them consistent throughout the week? Would it make a difference?" -Mike
That is a great question. And the answer is contingent on a couple of different things. First of all, it depends on the type of workouts that you do as well as your goals. I am going to guess that you are interested in losing as much body fat as possible while maintaining or possibly gaining muscle mass. If this applies to you and you are completing pretty intense workouts (using moderate to heavy weights with moderate to high reps such as 8-12 repetitions close to failure for multiple sets), then it may be a good idea to shift more carbohydrates towards the days that you train. If you are training in a way that will be depleting some of your muscle glycogen, your body will not only use the excess carbs as fuel for the muscle (instead of storing it as fat), but it can also help increase the amount of glycogen that your muscle can store, plus the water that goes with it. This means that your muscle will not only be stronger and bigger, but it will look fuller.
From a fat loss standpoint, it may be a good idea to keep the amount of weekly carbohydrates that you are ingesting currently at the same amount or reduce them slightly, while shifting intake to consume more on training days as opposed to off days. It may also be in your best interest to monitor your physique and see how this shift is affecting your body. In fact, a good friend of mine Sean Golden of buildingaleanbody.com actually found that while using this sort of protocol, he was actually able to increase his total amount of carb intake to roughly 300 grams a day while still dropping body fat! However, this was only done after careful monitoring and ensuring that his workouts were ample enough to be able to use this amount of carbohydrate. Careful monitoring is very important because while you may see some physique changes simply by cycling your carb intake, there is a good possibility that you will eventually hit a plateau. Once you notice that fat loss has stalled, it would be a good idea to either begin being in a total caloric deficit or increase your current deficit further.
Since you are already intermittent fasting, you understand that one of the main concepts of intermittent fasting is placing the majority, (if not all) of your food in the post-workout window. This is primarily because of two things that occur. First, you can induce a large insulin spike in response to reintroduction of food post workout, especially when ingesting foods such as carbohydrate and whey (Nilsson et al., 2004). This allows for the ingested carbohydrate to be transferred to the muscle to be stored as glycogen. Second, you have a large amount of GLUT-4 translocation in response to muscle contraction (such as what occurs during resistance training). GLUT-4 is a glucose transporter that transfers glucose from the blood into the muscle to be stored as glycogen. Muscle glycogen not only provides fuel for your workouts but also allows for storage of water in the muscle as well so your muscle looks and feels full. Further, the interesting thing about the GLUT-4 transporter is that it works independent of insulin, meaning that it doesn’t need insulin to work. That is an important detail for the context of this question because if muscle contraction does not occur (such as on an off day), you need insulin to be elevated to transfer glucose from the blood to the muscle and the potential of ingested carbohydrate to be stored in the muscle is decreased. Further, having elevated GLUT-4 translocation allows for glucose to be more likely stored in the muscle rather than converted to fat for storage. In essence, during the post workout period, you can ingest a large amount of carbohydrate and utilize both insulin and the GLUT-4 transporter, which increases the likelihood that the ingested carbohydrate will be stored as muscle glycogen rather than being transported into adipose tissue and then transformed into fat.
One last bit of advice. If you choose to take this route, it would be in your best interest to consider the following:
In closing, if you are trying to lose body fat and gain muscle at the same time, then it may be a good idea to shift your carbs towards your training days. It will not only help you look great, but it may help your performance all while helping you lose fat.
Collier, G., Greenberg, G., Wolever, T., & Jenkins, D. (n.d.). The Acute Effect of Fat on Insulin Secretion. The Journal of Clinical Endocrinology & Metabolism, 323-326.
Nilsson, M., Stenberg, M., Frid, A. H., Holst, J. J., & Björck, I. M. (2004). Glycemia and insulinemia in healthy subjects after lactose-equivalent meals of milk and other food proteins: the role of plasma amino acids and incretins. The American journal of clinical nutrition, 80(5), 1246-1253.