There are so many benefits in exercising or stimulating the muscles. Some of them are obvious like looks good, feel better, and getting stronger. There are other benefits that are not spoken frequently, such as, improving our immune system, brain health, secreting enzymes that has anti-inflammatory response, and fat metabolism (1).
As much as we want to take full advantage of benefit we can gain from building muscles, but how can we effectively do so, without gaining fat in a process? The answer is understanding and manipulating insulin.
First Law of Thermodynamics
First, let’s talk about how our body use energy. To understand this, we will need to understand we’ll need to understand the first law of thermodynamics, which states that “energy can be transformed from one form to another but cannot be created or destroyed”.
What does this mean? It means that our body can store energy or use energy that is from our food sources, however, our body itself cannot create energy. When we eat food, depending on what we are doing, body can either use or store energy for later use.
Therefore, macronutrients, micronutrients, supplements, or drugs cannot ignore this law.
However, depending on type of macronutrients (carb, fat, and protein) and how our body use those energy or calories, although they follow the law, is different.
Way Our Body Use Food as Energy
Calories have only two ways use in our body. One is immediate use and two is stored for later usage. When exercising, for example, we do want the energy immediately which can be used from stored calorie in a form called glycogen or more larger storage form called fat.
Ideally, we all want all our consumed and stored calories to use for recovering muscles and promoting muscle growth and not storing as a body fat. Whether the body would use the calories to restore muscle or stored as body fat is all depending on insulin and metabolic profile.
Basics of Insulin and Insulin Sensitivity
All dietary carbohydrate will be converted into glucose in small intestine and absorbed into blood stream. For immediate use glucose will be stored in liver and muscle as glycogen. For later use, glucose will be converted into triglycerides and stored as fat. Whether the glucose to be use as immediate energy or stored energy is determined by insulin.
Yes, whether we like it or not, when we consume food, insulin level rises, and we always store food energy in a form of glycogen or triglycerides. For healthy individual, muscle accounts for more than 80% of insulin stimulated glucose disposal and fat accounts for less than 15%.
Reason why obesity population is growing is because people are consuming too much carbohydrate or wrong types of carbohydrates than the liver and muscles can store. Therefore, all excess carbohydrate or glucose will be converted to triglycerides and stored as bodyfat.
This fact can also lead another fact to be true. Because people are less active or avoid building muscles for whatever reasons, capacity to store glucose in muscles are decreased, which will also lead into more glucose is sent to bodyfat.
In both cases, insulin sensitivity is decreased which also means that insulin resistance is starting to happen. This also means that increase in muscle stimulation to build muscles and lowering (not eliminating) carbohydrate consumption can help restore insulin sensitivity.
Carbohydrate Intake for Muscle Growth
While restoring the insulin sensitivity, muscle growth will also become essential, and we do need carbohydrate along with protein in our diet. Of course, not any carbohydrate but vegetable type carbohydrate such as, cruciferous vegetables, potatoes, and fruits.
Overall, it is good practice to limit carbohydrate intake for it is easy to overconsume carbohydrate which leads to decrease in insulin sensitivity. Decrease in insulin sensitivity or insulin resistance means there are more insulin floating in bloodstream.
It is very important to remember that when insulin is present in bloodstream, the body will not metabolize fat as energy source. Only time stored energy of fat is utilized is when the insulin level is low. Therefore, when insulin level is high in blood stream, the body is set to burn carbohydrate as energy source only. This will ultimately slow down the metabolic rate because energy from carbohydrate or glucose is smaller amount compared with fat. Whenever you feel like the metabolism is low or slow, it is possible that the insulin level is increased in the blood stream.
This is not good for those who are working out to build muscle and wanting to burn off because not only you cannot utilize fat as energy source, but you may also not have enough energy to complete the workout which will slow down the muscle building process.
Best timing to consume carbohydrate is immediately after the workout. Biggest reason is to restore glycogen in muscles that has been used during the session and able to utilize protein more efficiently. Although insulin inhibits fat metabolism, insulin can activate protein and glycogen synthesis which are essential for muscle growth. However, these two synthesis processes do not happen without physical activities.
Amount of carbohydrate is different from person to person; however, suggestion is ranging from 50-300g. Amount may vary due to the exercise intensity, body size and metabolic profile. Individual with insulin resistance or diabetes may need to keep the carbohydrate intake lower around 50-150g per day.
Conclusion
Although I am sharing information on function and effect of insulin and carbohydrates, these information does not mean that insulin and carbohydrates are bad. Excessively consumed carbohydrate which leads to decreased in insulin sensitivity which leads to high blood insulin concentration is bad.
Carbohydrate, with proper amount, timing, and quality, are important to our health especially when building muscles and restore energy for immediate use. Insulin plays important role in storing protein and glucose to our muscles to restore and repair for the muscles to become stronger. Use them wisely and you can maximize the benefits of muscles.
Kota Shimada
Reference:
1. Bay, M. L., & Pedersen, B. K. (2020, September 9). Muscle-organ crosstalk: Focus on immunometabolism. Frontiers in physiology. Retrieved November 4, 2021, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7509178/#!po=81.5789.
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