Maximizing Insulin Sensitivity for Superior Muscle Growth

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The importance of testosterone is pretty well known when it comes to building muscle, burning fat, and living a generally awesome, happy, and healthy life. Testosterone is what makes a man, a real man, and it’s one of the biggest factors in creating the ideal physique. But, as amazing as testosterone is, it isn’t the be-all, end-all of gaining lean muscle mass.

In fact, there’s another hormone that’s even more powerful than testosterone when it comes to rebuilding and reshaping your body. A hormone that, when put to maximum effectiveness, can channel anything you eat into pure muscle.

That hormone is insulin and if you’re not paying particular attention to optimizing your body’s insulin response, you’re missing out on some major gains!

What is Insulin?

Insulin is actually a protein or “peptide hormone” that is secreted by the β cells of the pancreatic islets of Langerhans.[1] It’s primarily known for regulating blood glucose levels by facilitating glucose uptake into your cells, but insulin also[4]:


Meet insulin — a peptide hormone (protein) composed of 51 amino acids that’s responsible for shuttling nutrients into muscles for repair and growth.

  • regulates carbohydrate, protein, and lipid metabolism
  • promotes cell division and growth (via mitogenesis)
  • decreases the rate of fatty acid oxidation in muscle and liver (i.e. reduces fat burning)
  • increases the rate amino acid delivery into tissues,
  • increases the rate of protein synthesis in muscle (i.e. builds muscle), adipose tissue, liver, and other tissues
  • decreases the rate of protein degradation in muscle (i.e. stops catabolism, “muscle breakdown”)
  • decreases the rate of lipolysis in adipose tissue
  • decreases the rate of glycogen breakdown

Right off the bat, you can see how critical insulin is for muscle growth. Without it, nutrients don’t make it into your muscles, which means no glycogen replenishment, no muscle repair, and no muscle growth!

Insulin was first theorized by German scientists Minkowski and von Mering in 1889 when they observed that complete removal of an animal’s pancreas led to the development of severe diabetes.[2] The two scientists hypothesized that some compound released by the pancreas played a critical role in metabolism. It wasn’t until 1921, that insulin as we know it today, was isolated, purified, and available for therapeutic administration.[1]

What Triggers Insulin Release?

Most of you reading this probably realize that carbohydrate (glucose) is the principal stimulus for insulin secretion, but that’s not the only macronutrient that stimulates insulin release. Protein, especially whey protein[3], can actually cause an insulin release as well as certain individual amino acids, other hormones, and neural input may affect insulin response as well.

Some of the other prominent catalysts for insulin secretion include[1]:


The BCAA, like those found in Condemned Labz Confined, are powerful stimulators of insulin secretion, which makes them invaluable for muscle growth.

  • L-Arginine
  • L-Leucine (one of the BCAA)
  • L-Valine (one of the BCAA)
  • L-Isoleucine (one of the BCAA)
  • L-Lysine
  • Acetylcholine (the “learning” neurotransmitter)
  • Glucagon
  • Secretin
  • Gastrin
  • Growth hormone

What Does Insulin Do?

Insulin is quite possibly the most anabolic hormone in the body. Yes, even more anabolic than testosterone or growth hormone. The reason, is that insulin is the hormone responsible for shuttling nutrients into your cells and thereby causing cell differentiation and growth, which leads to muscle growth.

But here’s the “catch” with insulin. It doesn’t discriminate. It’s an equal opportunity hormone that will just as easily shuttle nutrients into fat cells as it will skeletal muscle cells. There are a few things you can do to entire insulin “entice” insulin to preferentially shuttle nutrients into muscle cells only, but we’ll get to that a bit later.

Now, back to how insulin works in the body…

The primary function of insulin is to transport nutrients from the bloodstream and into muscle cells (and fat cells, too).

Insulin’s main job is to keep blood sugars in the “steady” range, which is between 80-100 mg/dl. In the instance blood glucose levels rise above 100 (i.e. you eat a carb heavy meal), the pancreas secretes insulin to “pick up” the extra glucose floating in your blood and store it in one of three places:

  • Muscle glycogen
  • Liver glycogen
  • Adipose tissue

Obviously, we’d prefer insulin only store nutrients in options 1 or 2, but that’s not the way insulin works. If there’s an “open slot” somewhere, that’s where insulin will store it. So, with that in mind, let’s see how insulin affects both muscle growth and fat gain.

Insulin and Muscle Growth

After you eat carbs, protein, or a mixed meal, the pancreas detects a rise in blood sugar levels and releases insulin to deal with the rising blood sugar concentrations. While in the blood, insulin travels to different tissues throughout the body, including muscle and fat cells. Muscle cells are lined with insulin receptors, and these “receptors” are more or less like docking bays.

When the insulin molecule docks at the station, it signals the muscle cell to open up and allow insulin to transfer in glucose, amino acids, and creatine, which go towards replenishing muscle glycogen, repairing muscle tissue, and bolstering phosphocreatine stores.


Without optimizing insulin sensitivity, you’ll never be able build a stellar physique, like Condemned Labz’ own @_antonioluis

Now you can begin to see the true anabolic power of insulin. It’s literally responsible for delivering the essential nutrients your muscles need for repair and growth.

Basically, without insulin, all that protein in your post workout shake isn’t doing a bit of good for helping you gain lean muscle mass. Now, let’s see how insulin promotes unwanted fat gain.

Insulin and Fat Gain

When insulin is released into the bloodstream, it signals the body that it has been fed, which means the natural fat burning mechanisms of the body are shut off. Since the body is always wanting to spare and conserve energy, when there is food in your system, it prioritizes using that food and storing any excess, rather than running on your stored energy (a.k.a. body fat).

This is where insulin enters the fat gaining part of the puzzle. Fat cells are wired with the same type of receptors we discussed on muscle cells. When insulin docks at the receptor, it facilitates the transfer of glucose and fats. The more sugar and fat consumed, the more is stored in your fat cells, and the less stored fat that is used for energy production. Here’s where you can begin to see how constantly spiking insulin levels during the day can lead to fat gain.

Insulin Sensitivity

Insulin sensitivity describes how “efficient” your body is with dealing with increases in blood sugar. In a healthy individual with normal insulin sensitivity, they require smaller amounts of insulin to lower blood glucose levels. If you have poor insulin sensitivity (insulin resistant), you require larger and larger amounts of insulin to deal with the escalating blood sugar levels.

Having insulin resistance is a tell-tale sign that you’re experiencing difficulty metabolising glucose, and is often a warning sign of future health complications including high blood pressure, heart disease, heart failure, obesity, type 2 diabetes and even cancer. On top of that, having poor insulin sensitivity also means you’re more likely to store fat when eating an excess number of calories, rather than have it go towards skeletal muscle tissue.

How to Optimize Insulin Sensitivity


Weight lifting is one of the best things you can do to improve insulin sensitivity, even if you were born with poor genetics

The good news, is that just because you may have poor insulin sensitivity right now, you’re not doomed to be that way forever. By controlling your insulin levels during the day, you can “hack” your own biology to build muscle and burn fat daily.

Anytime insulin levels rise, your body’s natural fat burning mechanisms are shut down, and your body switches into energy storage mode. So, maximizing insulin sensitivity for muscle building and fat burning starts with structuring your diet around your training. Consuming the majority of your carbs before, during, and after training means that insulin will shuttle glucose into your muscles to replenish glycogen and not towards the increasing your fat stores.

That means, the rest of the day, you want to avoid huge spikes in insulin. So, other meals aside from those around training should be full of fiber, low in fast-acting (insulin-spiking), simple sugars/carbs, and higher in fat. All of these factors help lower the glycemic index of your meal, which reduces the insulin release that must happen to remove excess blood sugar.

Additionally, a few other tricks you can use to improve insulin sensitivity in your everyday life include:

  • Resistance-training (i.e. weight lifting)
  • High Intensity Interval Training (HIIT)
  • Losing body fat
  • Get sufficient sleep (7-9 hours per night)
  • Reduce stress levels

By turning the table and making insulin work for you instead of against you, you’ll be able to experience unparalleled muscle growth, fat loss, and body recomposition, no longer struggling with those “poor genetics”. And, if you need some extra help getting insulin under control, Condemned Labz has created the ultimate glucose disposal agent / insulin mimetic in HumaSlin!


Make Insulin Work for You with HumaSlin!


It’s time to make carbs start working for you instead of against you with Condemned Labz HumaSlin, the premier glucose disposal agent.

HumaSlin is the ultimate nutrient shuttling agent that optimizes your body’s natural insulin response for maximum muscle growth. The complementary matrix of ingredients in HumaSlin helps you avoid untimely insulin spikes that promote unwanted fat gain, and ensures that any carbs you do eat, go towards building muscle NOT fat!

Take 1 serving with your pre training meal, and another serving with your post workout meal to optimize glucose uptake into skeletal muscle ensuring rapid glycogen replenishment, reduced muscle soreness, and superior muscle growth.


  1. Wilcox G. Insulin and Insulin Resistance. Clinical Biochemist Reviews. 2005;26(2):19-39.
  2. Bliss M. The history of insulin Diabetes Care. 1993;16(Suppl 3):4–7.
  3. Salehi, A., Gunnerud, U., Muhammed, S. J., Östman, E., Holst, J. J., Björck, I., & Rorsman, P. (2012). The insulinogenic effect of whey protein is partially mediated by a direct effect of amino acids and GIP on $β$-cells. Nutrition & Metabolism, 9(1), 48.
  4. Dimitriadis, G., Mitrou, P., Lambadiari, V., Maratou, E., & Raptis, S. A. (2011). Insulin effects in muscle and adipose tissue. Diabetes Research and Clinical Practice, 93 Suppl 1, S52-9.

About Author


"My road to the fitness and supplement industry was long and winding. Following in my father and grandfather's footsteps, I pursued a degree in engineering. After graduating with a Mechanical Engineering degree in 2008, I made my living as an oil & gas engineering consultant designing everything from refinery pumping and piping equipment to full-blown offshore oil rigs. Although I had always been active in martial arts since childhood, I never caught the "lifting bug" until my grandfather's death in January 2010. From that day, there was a significant shift in my mindset towards health, fitness, and nutrition. Like many people, my entry into the lifting world was through some home workout DVDs which sparked my interest in nutrition and supplementation, and how that impacted workout performance and recovery. This led to endless hours devoted to reading, researching, and studying anything and everything I could get my hands on in regards to training, nutrition, and sports supplements -- all while still working 9-10 hours a day as a full-time engineer. This dual-sided life continued for 6 years until I decided to forego the stability and success I had experienced as an engineer and dive headfirst into a career as a full-time writer, researcher, and unabashed supplement geek. I do not regret my time spent engineering or the years of schooling it took to get there. If anything it prepared me for my current career and makes it that much easier to understand the rather "thick" material that comes with supplement research and distill it for the average person to understand. Since leaving the engineering world in March 2015, I don't feel like I've worked a day in my life. Funny how your view of "working" changes when you're pursuing your passion."

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