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IGF-1 LR3 Review: An Anabolic Peptide for Bodybuilding?

igf-lr3 peptide

The global sports nutrition market, monstrous in both size and influence, is projected to reach a staggering $81.5 billion by 2026.

And where does the majority of that come from?

The +4,000 supplement brands promising miraculous health outcomes.

Competitive bodybuilders, high-performing athletes and even everyday gym-goers are increasingly turning to supplements to improve their health in every way possible.

But how do you know if you are using the right one?

The truth is only a small fraction of them truly deliver on their promises. 

Many of these supplements have short half-lives, forcing you to buy and consume more just to see minimal results. 

Even worse, some can lead to adverse side effects, jeopardizing your efforts and even your long-term health.

Could all of this change if more people started using the IGF-1 LR3 peptide?

Many of its users claim you can train harder, recover faster, and achieve real lasting muscle growth in the context of health and longevity.

But in this corner of the Internet, all claims are fully examined using the latest scientific evidence and experiential knowledge accumulated over decades.

So keep reading if you want to learn more about IGF-1 LR3 and whether it can help you transform your physique.

What is IGF-1 LR3 Peptide?

IGF-1 LR3 peptide

Insulin-like growth factor-1 Long R3, or IGF1-LR3, is a modified version of the hormone known as insulin-like growth factor (IGF-1).

It has 83 amino acid analogs of IGF-1 and this includes the complete human IGF-1 sequence, with the only difference being that Glu (E) is substituted with Arg (R) at position #3. 

And unlike regular IGF-1, IGF-1 LR3 has an additional 13 amino acids attached to its N-terminal end.

This extends the peptide’s half-life to 20 times that of native IGF-1, significantly boosting its bioavailability and making it far more effective at promoting muscle growth.

Thanks to its anabolic effects on muscle tissue, bodybuilders and athletes alike are using IGF-1 LR3 to maximize their muscle growth without experiencing serious side effects.

Understanding Insulin-like Growth Factor-1

IGF-1 LR3 peptide

Insulin-like growth factor-1 (IGF-1), formerly known as somatomedin or somatomedin C, has a “single chain 70-amino acid polypeptide cross-linked by 3 disulfide bridges.”

Although IGF-1 provides several benefits similar to insulin such as lower blood sugar levels, the key difference is that “insulin mediates mainly a metabolic response, whereas IGF-1 mediates growth-promoting effects” (Source).

More specifically, IGF-1 works well in promoting and managing the effects of growth hormone in the body. 

For example, it helps in cell growth and division, especially in skeletal muscle cells. 

When binding to a receptor on muscle cells, IGF-1 activates signaling pathways that promote protein synthesis and stop protein breakdown.

This biological cascade promotes muscle mass growth while reducing muscular atrophy (i.e. muscle wasting).

IGF-1 also stimulates the differentiation and proliferation of satellite cells, which helps in the repair of damaged muscle tissue after intense exercise and/or an injury. 

Mechanisms of IGF-1 LR3 Peptide

IGF-1 LR3 peptide

IGF-1 LR3 has several mechanisms of action in the body. 

Primarily, it boosts muscle strength and mass by binding to the IGF-1 receptor on muscle cells via the PI3K/Akt/mTOR and PI3K/Akt/GSK3β pathways.

As a result, IGF-1 LR3 promotes muscle protein synthesis and stops muscle protein breakdown. 

Second, it can also stimulate satellite cell differentiation and proliferation, helping in the repair of damaged muscle tissue.

Other notable effects include:

Benefits of IGF-1 LR3

IGF-1 LR3 peptide

Fat Loss

IGF-1 LR3 promotes lipolysis, which helps reduce body fat and prevents the storage of new fat cells in the body.

When paired with exercise, IGF-1 LR3 can enhance fat metabolism to help users achieve a lean and muscular body. 

So in a way, you can also think of it as a weight loss peptide.

It also inhibits glucose transport into cells so the body can use the glucose for energy, therefore allowing you to train harder and burn fat more effectively.

Additionally, IGF-1 LR3 helps reduce cravings and hunger pangs, making it easier to avoid unhealthy foods and stay on track with your diet. 

In a study published in the Journal of Metabolism, researchers found that individuals with obesity tend to have lower levels of IGF-1.

At the same time, those who successfully lose weight show a significant increase in their IGF-1 levels.

This goes to show that maintaining a healthy weight can positively impact IGF-1 levels, potentially improving overall metabolic health while aiding in muscle growth and recovery:

“This study aimed to characterize the association between serum insulin-like growth factor-1 (IGF-1) and obesity, as well as fat distribution, before and during moderate energy restriction (1,200 kcal/d). 

In 51 females and nine males having a body mass index (BMI) between 27 and 39 kg/m2, relationships between serum IGF-1, IGF-binding protein-3 (IGFBP-3), insulin, growth hormone (GH), blood glucose, and anthropometric measurements of body fat were examined. 

The patients were studied before treatment and again after 8 and 16 weeks of dieting. 

Visceral adipose tissue (AT) was estimated by anthropometric computed tomography (CT)-calibrated equations. 

In females, IGF-1 was inversely associated with the abdominal sagittal diameter (SagD) and with the visceral AT (r = -.41, P = .006). No significant correlations were found between IGF-1 and BMI or other indices of adiposity. 

Weight loss caused a temporary increase in IGF-1 concentrations (P = .03) and continued decrements in blood glucose levels (P = .0004 at 16 weeks). 

A statistically significant inverse correlation between IGF-1 and blood glucose levels was present before (r = -.30, P = .02) and after 8 (r = -.37, P = .007) and 16 (r = .02, P = .02) weeks of dietary treatment. 

Both serum IGF-1 and insulin levels were positively correlated with serum IGFBP-3 levels (r = .34, P = .009 and r = .34, P = .008, respectively).

We conclude that IGF-1 levels in obese females reflect the intraabdominal fat mass rather than obesity per se. IGF-1 and blood glucose levels are inversely correlated in obesity before and during energy restriction.”

Muscle Growth

IGF-1 LR3 is well-known in the biohacking world as a peptide that boosts muscle growth and strength.

Thanks to its ability to promote nitrogen retention, your body can hold onto more protein for protein synthesis, which helps with muscle growth and tissue damage repair. 

IGF-1 LR3 also protects you from bodily inflammation while promoting the repair of muscle damage that stems from high-intensity workouts, thus speeding up your recovery. 

A study in the Biochemical Journal showed that mice given IGF-1 LR3 experienced a 2.5x degree of anabolic muscle-building effects compared to mice receiving stand-alone IGF-1:

“The administration of insulin-like growth factor-I (IGF-I) via subcutaneously implanted osmotic pumps partially reversed a catabolic state produced by the co-administration of 20 micrograms of dexamethasone/day to 150 g male rats. 

Marked dose-dependent effects on body weight and nitrogen retention were produced, with the highest IGF-I dose, 695 micrograms/day, giving a 6 g increase in body weight over 7 days, compared with a 19 g loss in the dexamethasone-only group and an 18 g gain in pair-fed controls. 

Two IGF-I analogs that bind poorly to IGF-binding proteins, the truncated form, des(1-3)IGF-I, and a variant with an N-terminal extension as well as arginine at residue 3, LR3IGF-I, were approx. 2.5-fold more potent than IGF-I. 

The response with LR3IGF-I was particularly striking because this peptide binds 3-fold less well than IGF-I to the type 1 IGF receptor. 

The increased potencies of the IGF-I variants may relate to the substantially increased plasma levels of IGF-binding proteins, particularly IGFBP-3, produced by the combined treatment of dexamethasone with IGF-I or the variants. 

These binding proteins would be expected to decrease the transfer of IGF-I, but not that of the variants, from blood to tissue sites of action. 

Measurements of muscle protein synthesis at the end of the treatment period and muscle protein breakdown by 3-methylhistidine (3MH) excretion throughout the experiment indicated coordinated anabolic effects of the IGF peptides on both processes. 

Thus 3MH excretion was decreased at the highest IGF-I dose from 83.5 +/- 4.2 (S.E.M.) mumol/kg per 7 days to 65.1 +/- 2.2, compared with 54.9 +/- 1.2 in the pair-fed controls. 

Part of this response in 3MH excretion may have reflected a decrease in gut protein breakdown because IGF-I, and especially the IGF analogs increased the gut weight by up to 45%. 

Notwithstanding the effects on protein synthesis and breakdown, the fractional carcass weights remained low in the IGF-treated groups, although the increase in total carcass weight reflected nitrogen rather than fat gain. 

The dexamethasone-induced changes in the liver, spleen, and heart weight were restored to normal by the IGF treatment. 

The experiment demonstrates the potential of IGF-I treatment of catabolic states and especially the value of modified forms of growth factors that bind weakly to IGF-binding proteins.”

In another study in the Journal of Developmental Cell, IGF-1 LR3 was shown to help prevent muscle wasting and stimulate muscle growth through the activation of the IGF1R/IRS1/PI3K/Akt pathway.

For those of you who aren’t well-versed in biochemistry, just know pathway helps promote skeletal muscle hypertrophy:

“Insulin-like growth factor 1 (IGF1) induces skeletal muscle hypertrophy by activating the IGF1R/IRS1/PI3K/Akt pathway. 

However the effect of IGF1 in differentiated muscle is limited by IRS1 ubiquitination and proteasome-mediated breakdown. I

n skeletal muscle, IGF1R activation sensitizes IRS1 to degradation, and a screen for the responsible E3 ligase identified Fbxo40 as mediating this rapid turnover of IRS1, since IRS1 loss can be rescued by knockdown of Fbxo40. 

In biochemical assays, an SCF E3 ligase complex containing Fbxo40 directly ubiquitinates IRS1, and this activity is enhanced by increased tyrosine phosphorylation of IRS1. Fbxo40 is muscle specific in expression and is upregulated during differentiation. 

Knockdown of Fbxo40 induces dramatic hypertrophy of myofibers. 

Mice null for Fbxo40 have increased levels of IRS1 and demonstrate enhanced body and muscle size during the growth phase associated with elevated IGF1 levels.” 

Moreover, IGF-1 LR3 also helps with muscle repair via improving the proliferative capacity of muscle satellite cells (MSCs)

MSCs are important for muscle fiber repair, maintenance, and remodeling:

“Skeletal muscle is an essential tissue that attaches to bones and facilitates body movements. 

Insulin-like growth factor-1 (IGF-1) is a hormone found in the blood that plays an important role in skeletal myogenesis and is importantly associated with muscle mass entity, strength development, and degeneration and increases the proliferative capacity of muscle satellite cells (MSCs). 

IGF-1R is an IGF-1 receptor with a transmembrane location that activates PI3K/Akt signaling and possesses tyrosine kinase activity, and its expression is significant in terms of myoblast proliferation and normal muscle mass maintenance. 

IGF-1 synthesis is elevated in MSCs of injured muscles and stimulates MSCs proliferation and myogenic differentiation. Mechanical loading also affects skeletal muscle production by IGF-1, and low IGF-1 levels are associated with low handgrip strength and poor physical performance. IGF-1 is potentially useful in the management of Duchenne muscular dystrophy, and muscle atrophy, and promotes neurite development. 

This review highlights the role of IGF-1 in skeletal muscle, its importance during myogenesis, and its involvement in different disease conditions.”

Finally, IGF-1 LR3 helps inhibit muscle breakdown, thus preserving muscle protein content and mass as shown in a study using a rat model of hind limb suspension (HLS).

“Muscle atrophy and wasting is a serious problem that occurs in patients with prolonged debilitating illness, burn injury, spinal injury, as well as with space flight. 

Current treatment for such atrophy, which often relies on nutritional supplementation and physical therapy, is of limited value in preventing the muscle wasting that occurs. 

Considerable recent attention has focused on the use of anabolic growth factors such as insulin-like growth factor (IGF-1) in preventing muscle atrophy during limb disuse or with various catabolic conditions. 

However, potential side effects such as hypoglycemia appear to be limiting factors in the usefulness of IGF-1 for clinical treatment of muscle wasting conditions. 

The formulation of IGF-1 used in this study (IGF-1/BP3) is already bound to its endogenous-binding protein (BP3) and, as a result, has a greater specificity of action and significantly less hypoglycemic effect. 

Using a rat model of hind limb suspension (HLS) for 10 days, we induced marked muscle atrophy that was accompanied by enhanced muscle proteolysis and reduced muscle protein content. 

When HLS rats were treated with IGF-1/BP3 (50 mg/kg, b.i.d.), they retained greater body and muscle mass. 

Muscle protein degradation was significantly reduced and muscle protein content was preserved. 

The rate of protein synthesis, although somewhat reduced in HLS muscle, was not significantly elevated by IGF-1/BP3 treatment. 

Volume density of HLS-treated muscles were increased compared to untreated HLS rats and the actual number of fibers per area of muscle was likewise increased.” 

Energy Levels and Metabolism

Apart from helping you build muscle and lose body fat, IGF-1 LR3 can also boost your energy levels and upregulate metabolism

This makes it a useful peptide for higher energy levels, and therefore allows you to achieve peak performance 

This means you’ll experience a greater degree of sustained energy you can use for more effective and efficient gym sessions.

Moreover, many studies have shown a clear connection between IGF-1 deficiency and metabolic syndrome. 

In vitro and in vivo studies demonstrate an IGF-1 deficiency can deregulate lipid metabolism, increase the risk of cardiovascular disease, and compromise the metabolic profile of diabetic patients. 

This was shown when a group of mice had improved symptoms of Metabolic Syndrome (MetS) — including better regulation of glucose, triglycerides, and cholesterol levels — after being given IGF-1.:

“Insulin growth factor 1 (IGF-1) has multiple effects on metabolism. Much evidence suggests that the deficiency of this hormone increases insulin resistance, impairs lipid metabolism, augments oxidative damage and deregulates the neuro-hormonal axis. 

An inverse relationship between IGF-1 levels and the prevalence of Metabolic Syndrome (MetS) with its cardiovascular complications has been identified. 

However, the underlying mechanisms linking IGF-1 and MetS are still poorly understood. 

In order to elucidate such mechanisms, the aim of this work was to study, in mice with partial IGF-1 deficiency, liver expression of genes involved in glucose and lipid metabolism as well as serum levels of glucose, triglycerides and cholesterol, as well as liver malondialdehyde (MDA) levels, as a marker for oxidative damage.

Three experimental groups were studied in parallel: Controls (CO), wild type mice (igf-1 (+/+)); untreated heterozygous mice (Hz, igf-1 (+/-)) and Hz (igf-1 (+/-)) mice treated with low doses of IGF-1 for 10 days (Hz + IGF-1).

A reduction of IGF-1 serum levels in the Hz group was found, which was normalized by IGF-1 therapy. 

Serum levels of glucose, triglycerides and cholesterol were significantly increased in the untreated Hz group as compared to both controls and Hz + IGF-1 groups. 

The expression of genes involved in gluconeogenesis, glycogenolysis, lipid synthesis and transport, and catabolism were altered in untreated Hz animals and the expression of most of them was normalized by IGF-1 therapy; MDA was also significantly increased in the Hz untreated group.

The mere partial IGF-1 deficiency is responsible for the reduction in the expression of genes involved in glucose and lipid metabolism, resulting in dyslipidemia and hyperglycemia. Such genetic alterations may seriously contribute to the establishment of MetS.”

Recommended Dosage and Usage Guidelines

IGF-1 LR3 peptide

While the FDA does not provide specific dosage guidelines for using IGF-1 LR3, the best recommendation comes from my protege Hunter Williams.

In his Peptide Cheat Sheet, he recommends the following:

50mcg injected subcutaneously in the morning or 10-30 minutes before a workout, and within a “10 days on, 4 weeks” off cycle. 

First-time users should start at a lower dose of 20mcg, monitor their symptoms for two weeks, and gradually titrate the dose upwards to 50mcg.

Cycling IGF-1 LR3 is also crucial to avoid peptide antibody buildup and any potentially adverse side effects.

Comparing IGF-1 LR3 with Other Growth Factors

IGF-1 LR3 peptide

IGF-1 LR3 vs. Regular IGF-1: Key Differences

IGF-1 helps with muscle growth and development, but its natural form is only active in the body for a very short period of time.

To improve its effectiveness, scientists modified the original IGF-1 molecule to create IGF-1 LR3, a modified version with a longer half-life of about 20-30 hours.

This molecular change makes it more potent and allows its effects to be exerted throughout the day.

The benefits of IGF-1 LR3 over IGF-1 include:

  • Longer-lasting effects
  • Better muscle growth due to its lower binding affinity for proteins like IGFBP-3
  • Fat burning via inhibition of glucose movement into the cells (which forces the body to tap into fat for energy production.)

Additionally, IGF-1 LR3 is more convenient to use as it doesn’t require site injections. 

It cycles through the whole body, binds to muscle receptors, and stays active for about a day. 

IGF-1 LR3 and Testosterone

As you age, your natural testosterone production declines, causing symptoms such as low energy, reduced muscle mass, and decreased libido. 

Testosterone replacement therapy (TRT), or the use of peptides to boost testosterone levels, can help restore your testosterone to healthy levels and support muscle growth.

IGF-1 LR3, on the other hand, helps stimulate cell growth and regeneration within muscle cells, making it a favorite among athletes and bodybuilders for enhancing performance and muscle gains.

However, combining TRT with IGF-1 LR3 creates a desirable synergistic effect.

TRT increases your testosterone, which enhances protein synthesis, reduces muscle breakdown, speeds up recovery, and improves nitrogen retention.

The end result is more fat mass lost and more lean mass gained.

IGF-1 LR3 directly impacts your muscle cells by boosting amino acid uptake, increasing protein synthesis, and promoting satellite cell proliferation (all of which are important for muscle repair and growth). 

Together, TRT and IGF-1 LR3 foster an ideal environment for muscle growth and recovery, resulting in:

  • Faster muscle gains
  • Shorter recovery times
  • Increased strength
  • Improved endurance
  • Enhanced overall performance

Therefore, if you’re a competitive athlete wanting to reach your fitness goals faster and more effectively, the combined power of TRT and IGF-1 LR3 is worth looking into.

Potential Side Effects of IGF-1 LR3

IGF-1 LR3 peptide

While IGF-1 LR3 is generally safe when used correctly, excessive use can cause possible side effects that include:

  • Muscle and joint pain
  • Nausea
  • Headache
  • Low blood sugar
  • Fatigue
  • Soft tissue swelling

Pain or discomfort at the injection site is common but usually subsides after a couple of weeks.

However, abuse of IGF-1 LR3 can lead to the infamous “bubble gut,” which can eventually cause abdominal bloating.

Therefore, if you are new to using IGF-1 LR3, make sure to start with the recommended dose and gradually titrate up where appropriate.

Prolonged abuse of IGF-1 LR3 may also lead to:

  • Acromegalic cardiomyopathy, a simultaneous enlargement and weakening of the heart. 
  • Irregular cardiac rhythm due to receptor saturation
  • Unwanted bone and gastrointestinal tissue growth, potentially causing irreversible changes to your physical structure (mostly seen in one’s face)

Again, follow our recommended dosage and administration guidelines if you want to use IGF-1 LR3 safely.

And don’t forget to consult with your doctor before using the IGF-1 LR3 peptide as it may be a contra-indication for a pre-existing medication and/or condition.

Jay’s Closing Thoughts

Similar to PEG-MGF, I AM of the stance that IGF-1 LR3 is largely worthless in isolation for anyone who is serious about building a muscular physique.

(Make sure to read “Jay’s Closing Thoughts” in the article I just linked for a deeper explanation)

Once again, bodybuilders continue to only use proven agents such as Therapeutic testosteronepharma-grade HGH, anabolic steroids, insulin and maybe pure IGF-1 (good luck finding it).

There’s a good reason why you won’t see them talk about peptides in the context of muscular hypertrophy.

HOWEVER… my protege Hunter Williams has good things to say about IGF-1 LR3 as someone who has used the peptide with great success.

I AM telling you to watch his deep-dive video if you’re on the fence about using IGF-1 LR3:

In this comprehensive guide, Hunter will show you:

  • How to stack IGF-1 LR3 with peptides such as HGH, BPC-157, and 5-Amino 1MQ to maximize its effects
  • Why IGF-1 LR3 is a great peptide for women to use
  • The phenomenal pumps Hunter experiences when using IGF-1 LR3 right before a workout
  • What you must know about its purported side effects (and how you can avoid them)

IGF1-LR3 Peptide Review Key Takeaways

IGF-1 LR3 peptide

IGF-1 LR3 is a synthetic and modified form of IGF-1 that offers the same benefits to a greater degree due to its significantly longer half-life. 

On top of promoting the growth of new lean muscle by influencing growth hormone (GH) levels, it also boosts your athletic performance by increasing your energy levels. 

But don’t just order and buy IGF-1 LR3 from anywhere – always make sure to purchase it from a trusted source like Limitless Life Nootropics.

I trust Limitless Life Nootropics because they are the biohacking industry’s only reliable vendor for 3rd-party tested research products.

They have the best formulations of therapeutic peptides available, and no other vendor comes close to offering them at ultra-high levels of purity for reasonable prices.

HOWEVER: IGF-1 LR3 is not currently stocked by Limitless.

For potential muscle gain via the peptide route, you’ll want to seek out agents such as 5-Amino 1MQ, Ipamorelin, and Tesamorelin.

Use code JAY15 to get 15% off your order

But before you start injecting these peptides into your body recklessly, make sure you first read the Top 10 Mistakes People Make When Starting Therapeutic Peptides FREE PDF!

Seriously, this short e-book will save you a lot of wasted money and poorly spent time (not to mention preventing you from potential self-inflicted missteps).

And the emails I’ll send you after downloading the book contain EXCLUSIVE 20% OFF discount codes code for all my amazing courses on using therapeutic peptides, such as:

Peptides Demystified (THE #1 course for newbies when learning to use peptides)

The Modern Woman’s Peptide Course (A course made by women for women on using therapeutic peptides)

The Ultimate GLP-1 Video Masterclass (Learn how to use GLP-1 peptides to live leaner, longer & stronger)

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