Efficiency of insulin use in bodybuilding
I see many people using insulin today, almost always unnecessarily, and often causing harm to the physique, with minimal benefit. The truth is that insulin is only really efficient for muscle mass gain in high doses, preferably in combination with GH and steroids of course.
Studies show that low doses of insulin are not effective in increasing protein synthesis. Furthermore, by using exogenous insulin in low doses (10-20IU) you are often just replacing your physiological demand. Furthermore, by increasing the amount of food (large caloric surplus) to compensate for a greater use of insulin, it will end up favoring fat gain (by stimulating lipogenic enzymes and lipid synthesis). Insulin also strongly inhibits lipolysis, so when there is no counterpart of increased metabolic rate and increased use of lipolytic hormones such as GH, fat gain may be much more favored than muscle mass gain. Of course I am always considering the use of androgenic steroids, as the use of insulin alone would be too stupid to discuss here. Another thing is that an increase in insulin levels also leads to a decrease in its receptors and also a competition for the IGF-1 receptors. If you have high insulin levels it is also extremely important to increase your insulin sensitivity.
Everything indicates that insulin abuse only became common in the early 90's, precisely because bodybuilders began to abuse GH and other thermogenic drugs as well. That's how they realized that only high doses of insulin were effective in increasing muscle volume, and synergizing with GH and steroids. What I can say is that I don't see any sense in lighter athletes being abusing insulin, especially if they don't use GH. The use of insulin in my view only makes sense to a minority of athletes, and this can be seen in practice, a lot of people using insulin with a much smaller physique than athletes from the 70s-80s, who didn't even use this hormone. I can also say that athletes with greater genetic potential have greater sensitivity to insulin and androgenic steroids, and achieve large volumes of muscle mass without the need to use it, but the less fortunate will not have great benefits if they do not have patience and a hormonal environment appropriate. Anyway, I don't find it effective for an athlete below 90-100 kg dry (for a standard height of ~1.75m) to use insulin, at least in most cases. And those who choose to abuse this weight range probably won't get very far in bodybuilding, probably because they have limited genetic potential.