There is much confusion concerning types of carbohydrates, benefits/drawbacks of insulin, and their role in fat gain. We’ll try to clear that up here.
Insulin is not, as commonly thought, a fat storage hormone. It is a storage hormone, but that does not mean it is solely a *fat storage hormone.
When you eat carbohydrates, either high or low GI, your blood sugar is elevated. High GI carbs such as pop tarts will elevate your blood sugar more rapidly and low GI carbs will elevate it more slowly but that is not as important as some would believe as we will see later.
When your blood sugar (glucose) is elevated, the body is signaled to produce insulin to carry the glucose and other nutrients to storage. This is where most people get lost in the weeds. Just because it is going to storage, does NOT mean they are going to be stored as fat.
Insulin prioritizes the blood glucose to go where it is needed, starting with muscle cells where it is turned into glycogen (if they are depleted), then the liver, THEN as fat.
When you weight train, your body uses the glycogen stored in the muscles for energy; this means at the end of the session, your muscles will be glycogen depleted. Keeping this in mind, you would WANT to eat carbs to spike blood sugar and allow insulin to be released so your recently depleted muscles can be replenished with glycogen for the next session.
This is why I and many other trainers acknowledge the fact that low/no carb diets are not a good idea for anyone wanting to increase or sustain muscle mass. They are essential for growth.
Regarding high GI vs low GI carbs, people normally use them in a backwards manner. High GI carbs such as sugary and/or processed foods will spike blood sugar quickly flooding the blood stream with more glucose and insulin to guide it as opposed to a lower GI carb such as oatmeal. Most trainees see this as an excuse to allow themselves to eat poorly in the offseason (pop tarts, etc.) while dialing it in during prep.
This is completely backwards.
When you are dieting, your muscle cells are constantly depleted so high or low GI carbs don’t really matter; the glucose will be used to replenish them and none will spill over to fat cells.
When in the offseason, you are eating more so your muscle and liver glycogen levels are close to full so there is a much larger chance of excess glycogen being stored as fat.
Basically, don’t use the offseason as an excuse to get fat; that is the time when you must be most worried about storing carbs as fat. You will be less lean which leads to lower insulin sensitivity and, on top of the cells being less sensitive, they will also have less room to store it.
Hopefully this article has made you realize the importance of carbs and how to optimize your intake.