Home » INSULIN 101: Guide and protocol for optimal use in bodybuilding

INSULIN 101: Guide and protocol for optimal use in bodybuilding

January 27, 2024

Study on the anabolic hormone with additional tips by coach Justin Harris

MANY people will scare you into believing insulin use in bodybuilding will kill you.

In fact, some find difficulty in obtaining it because of such concern.

Proper insulin use does not kill. Stupidity and recklessness does.

While frontdouble.com is not suggesting anyone use insulin, this guide has been set up to outline the most optimal way to use it if you plan to, or if you already are using it.

For those who do not know, insulin is a hormone that is naturally produced in the body by your pancreas. The organ releases insulin into the bloodstream whenever you consume carbohydrates. It does this in order to regulate your blood sugar level. Insulin’s job is to transport that glucose [sugar] from your bloodstream and into your cells.

According to the website healthline: “It also encourages cells to take in amino acids (proteins) and lipids (fats) to a certain extent. Insulin also prevents the breakdown of glycogen, protein and fat in your body.”

In this sense, insulin is anabolic. A study published on Pub Med offers a concise explanation: “Insulin is considered to be an anabolic hormone in that it promotes the synthesis of protein and glycogen and it inhibits the degradation of these compounds in muscle tissue. Glucose normally provides energy sources for tissues of the body, its uptake by muscle requires a secretion of insulin. Insulin stimulates the uptake of amino acids into cells and simulates protein synthesis in muscle tissue.”

In an article for bodybuilding.com, Dr Jim Stoppani writes: “From the pancreas, insulin enters the bloodstream and travels to various tissues, including muscle tissue.

“The muscle fibers [or cells] are lined with insulin receptors, similar to a docking station. Once the insulin molecule docks on to the receptor, it signals the muscle cell to open up gates.

“This allows allow glucose, amino acids and creatine to enter the muscles. This process is a major reason why insulin is so important for building muscle.

“Insulin also indirectly aids in muscle development by causing the blood vessels to relax and dilate, allowing greater blood flow to the muscles. By increasing blood flow, insulin can help get even more nutrients like glucose and amino acids to the muscles.”

Bodybuilders use insulin to enhance this effect; to store more glucose in the muscle than they would with only the amount produced naturally by the pancreas.

Another decent analogy was described on a recent podcast called 'Blood, Sweat and Gear', with coaches Skip Hill, Andrew Berry and Scott McNally. You can watch what they say from the clip below:

When bodybuilders use insulin, they typically keep their fat intake at a minimum; ie. no added fats at all. The reason is because of fat storage.

For example, in the same way insulin will drive glucose to the muscle for storage, it can also drive fats to the fat cells for storage. Therefore, using a continued insulin protocol over time can lead to fat storage, which is perhaps why you might hear some people suggest ‘insulin makes you fat’. Of course, that is not true. In the same sense of eating fat does not make you fat, insulin use also does not make you fat. What makes you fat is poor use of insulin.

When to use insulin in bodybuilding

Perhaps the most optimal way to use it is within a carb-cycling diet, when the amount of carbs you eat varies each day depending on whether you rest, train or train a significant body part such as legs or back, when typically the most amount of calories are burned.

In a nutshell, insulin use in bodybuilding is most optimal when you are loading carbohydrates, in order to store the most possible as muscle glycogen.

Protocol for insulin use in bodybuilding

Frontdouble.com spoke to renowned coach Justin Harris, of Troponin Nutrition and 1st Detachment. He outlined his protocol for insulin use in bodybuilding, which uses the short-acting form of insulin, which is Humalog or Novorapid.

Harris says: “Insulin use is for high days only [when carbohydrates are at their highest]. We eat six meals on my diets and the dosing protocol is:

  • First meal of the day: 4-10iu Humalog [iu = international units]
  • Second or third meal of the day (not both): 4-10iu Humalog
  • Pre or Post workout (assuming it’s not second or third meal of the day): 4-12iu humalog

“What we are doing here is spreading out the dose over the day, roughly at every other meal more or less. We start at the low end – in my example here that is four international units per dose – and titrate up until you find the doses where you just start to go hypoglycemic on the diet plan.

“You want to stop at the dose where you almost go hypo, but don’t. Going hypoglycemic forces you to drink sugar above the calories in the diet plan – which is why people get fat from insulin.

“We want to find the optimal dose where the diet plan just barely covers the insulin with no hypoglycemia. That amount maximises glycogen storage and maximises amino acid uptake from the diet.

“This gives you about 18 hours per high day where insulin levels are supraphysiological. Compare this with about 15 hours per week if you use it every workout and only those times (5x per week).

“So you get more active hours from one high day than you do using it 5x per week post workout. This minimises any hit to insulin sensitivity and maximises time where levels are elevated.”

3: Why short-acting [Humalog/Novorapid, which starts working 15 after injection] rather than long-acting [Lantus]?

Harris explains: “It's more precise. Lantus works because it’s in your body 24-plus hours, so there’s always insulin. So your blood sugar is well controlled – but it’s like an alcoholic saying that as long as they drink one beer per hour all day, they never get DTs.

“Your blood glucose is controlled because of the lantus – because of the insulin. Your insulin sensitivity is getting worse by the day. But people misunderstand that because blood sugar is controlled.”

The take home message here is that short-acting insulin is more optimal because it offers more windows of opportunity for muscle growth without increasing damage to insulin sensitivity and therefore becoming diabetic.

Insulin is a powerful hormone and misuse/overdosing can result in a quick death.

The website John Doe Bodybuilding says, rather succinctly: “The biggest way to fuck up insulin is incorrect measurement.

“If I tell you to take five units of insulin and you load up 5cc’s as you would a steroid shot, or even load up five units as you would a GH shot, you are probably going to die.

“Five units of insulin means five tiny little lines or “clicks” on an insulin syringe. It will look like hardly anything in the needle – this is powerful shit and it doesn’t take much at all to do it’s job.

“The second biggest way to fuck up insulin is to not eat properly after administering it. As a general rule, for every one unit of insulin you inject, you need to take 10 grams of carbohydrates with it. This needs to be done within 15 minutes of injecting insulin. Depending on what type of insulin you use, you will want another meal within 60-90 minutes after that.”


  • Short-acting: Humalog/Novorapid: Starts working 15 minutes after injection. Lasts roughly three-five hours. In the above protocol, one injection covers two meals with insulin injected three times over the day].
  • Never inject, then prepare food. Always have your meal ready before injecting insulin.
  • Long-acting: Lantus [slow release throughout the day, so only needs one injection].
  • Hypoglycemic: Low blood sugar; the feeling of light-headedness, sweating, dizzyness and, in some cases fuzzy eyesight. Severe and/or prolonged hypoglycemia can lead to death.







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