IGF-1 Explained: The Growth Factor Behind Muscle, Metabolism, and Recovery

If you have spent any time reading about growth hormone, muscle building, or anti-aging, you have run into IGF-1. It gets name-dropped constantly, usually without anyone explaining what it actually is or why it matters. 

IGF-1 is one of the most important molecules behind how you build muscle, manage your metabolism, and recover from training and daily wear. It is also one of the most misunderstood, because more of it is not automatically better.

Below is a clear, accurate guide to what IGF-1 does, how it changes with age, the surprising nuance about ideal levels, and the evidence-based ways to support it.

Quick Summary

• IGF-1 (insulin-like growth factor 1) is a peptide hormone, made mostly by the liver in response to growth hormone (GH), that carries out much of GH's actual work in the body.

• It is a key driver of muscle repair and growth, supports bone and connective tissue, aids recovery and wound healing, and helps regulate metabolism.

• IGF-1 works by binding the IGF-1 receptor on nearly every cell, activating growth and repair pathways (notably PI3K/Akt/mTOR).

• Levels decline with age. IGF-1 falls roughly 14% per decade after early adulthood, reaching about 30 to 50% of peak by age 60 to 70, part of a process called somatopause.

• More is not better. The relationship between IGF-1 and health is U-shaped: both very high and very low levels carry risks, so the goal is a healthy, age-appropriate level, not the maximum.

• The strongest natural levers for healthy IGF-1 are resistance training, adequate protein, quality deep sleep, reducing visceral fat, and managing stress.

• Oral supplements do not reliably raise blood IGF-1, since IGF-1 is a peptide that is largely broken down in digestion, so a supplement should not be sold or understood as an IGF-1 booster.

• BioPro+ is a non-synthetic, system-support supplement designed to support the body's own processes as part of a healthy lifestyle, not a product that raises IGF-1 or replaces the fundamentals.

What Is IGF-1?

IGF-1 stands for insulin-like growth factor 1. It is a peptide hormone, about 70 amino acids long, with a structure similar to insulin, which is where the name comes from. Most of your circulating IGF-1 is produced by the liver, although many other tissues make it locally too.

The simplest way to understand IGF-1 is as growth hormone's messenger. Growth hormone is released from the pituitary gland in pulses, travels to the liver, and tells it to produce IGF-1. IGF-1 then circulates and does much of the work people credit to growth hormone, acting on muscle, bone, cartilage, nerve, skin, and other tissues. This is why scientists refer to the whole system as the GH/IGF-1 axis. If GH is the signal, IGF-1 is a primary courier delivering the instructions to your cells.

Once IGF-1 reaches a cell, it binds the IGF-1 receptor, which sits on the surface of nearly every cell type in the body. That binding switches on internal signaling pathways, most importantly the PI3K/Akt/mTOR pathway, that promote cell growth, protein synthesis, and survival while discouraging cell death. Its activity is fine-tuned by a family of carrier proteins called IGF-binding proteins, which control how much IGF-1 is free and active at any moment.

IGF-1 vs. Insulin: What's the Difference?

They are related but distinct. IGF-1 and insulin share a similar structure and some overlapping signaling, but they have different main jobs. Insulin, made by the pancreas, primarily manages blood sugar minute to minute. IGF-1, made mainly by the liver under GH's direction, primarily drives tissue growth, repair, and longer-term anabolic activity. Because they overlap, IGF-1 also has insulin-like effects on glucose, which is part of why the two systems are studied together.

What Does IGF-1 Do for Muscle, Metabolism, and Recovery?

This is where IGF-1 earns its reputation. Its effects cluster into three areas that matter most to active men.

Muscle Growth and Repair

IGF-1 is one of the central anabolic signals for skeletal muscle. It stimulates muscle protein synthesis and activates satellite cells, the muscle stem cells that proliferate and fuse to repair and build muscle fibers after training or injury. IGF-1 production rises locally in muscle that has been worked or damaged, which is part of how exercise translates into adaptation. Low IGF-1, by contrast, is associated with reduced grip strength and poorer physical performance, and when IGF-1 signaling falls too far, muscle wasting can follow. In short, IGF-1 is a major part of how your body turns training stress into stronger, larger muscle.

Metabolism

IGF-1 helps regulate how your body handles fuel. Because of its insulin-like effects, it influences glucose uptake and insulin sensitivity, and it plays a role in how the body partitions energy between building tissue and storing fat. The GH/IGF-1 system as a whole helps shift the body toward maintaining lean mass. This is also why IGF-1 sits close to the conversation about metabolic health, blood sugar, and body composition.

Recovery and Tissue Repair

Beyond muscle, IGF-1 supports the repair and maintenance of many tissues. It contributes to bone formation and remodeling, supports connective tissue and cartilage, aids wound healing and skin repair, and has protective and supportive roles in nerve and brain tissue. This broad repair role is why IGF-1 is so tied to how well, and how quickly, you bounce back, whether from a hard workout or the ordinary wear of daily life.

How Does IGF-1 Change With Age?

IGF-1 declines steadily as you get older, and the timing lines up with when many men start to feel a difference. After early adulthood, IGF-1 falls by roughly 14% per decade, so that by age 60 to 70 a typical person sits at only about 30 to 50% of their youthful peak. This decline is part of somatopause, the gradual age-related slowdown of the GH/IGF-1 axis, named by analogy to menopause.

That fall tracks with several familiar features of aging: slower recovery, gradual loss of muscle, reduced bone density, and changes in body composition. It is a major reason the GH/IGF-1 system attracts so much attention in the longevity and men's health space. But this is exactly where the story gets more interesting, and where a lot of online content gets it wrong.

Is Higher IGF-1 Always Better? The U-Shaped Truth

No, and this is the single most important nuance to understand about IGF-1. More is not better. The relationship between IGF-1 and long-term health is U-shaped, meaning both ends of the spectrum carry risk.

On the high end, persistently elevated IGF-1 promotes cell proliferation and blunts cell death, and epidemiological studies have linked higher IGF-1 to increased risk of certain cancers, including prostate and breast cancer. On the low end, especially in older adults, very low IGF-1 is associated with frailty, sarcopenia, reduced bone density, cognitive decline, and higher risk of cardiovascular disease and non-cancer mortality.

There is also a fascinating distinction researchers draw. People born with genetically very low IGF-1 signaling, such as those with Laron syndrome, appear strikingly protected from cancer and diabetes, and animals with reduced GH/IGF-1 signaling often live longer. Yet adult-acquired decline in IGF-1, the kind that comes with aging, illness, or inactivity, is generally harmful rather than protective.

The takeaway for most men is not to chase the highest IGF-1 possible, but to support a healthy, age-appropriate level, the middle of the curve, and to discuss your own numbers with a clinician rather than aiming for extremes.

How to Support Healthy IGF-1 Levels Naturally

The good news is that the levers with the best human evidence are practical and free. Here they are, ordered roughly by impact.

1. Lift weights. Resistance training is the most potent natural stimulus for the GH/IGF-1 axis. Compound movements done with progressive overload produce the strongest signal, and adding short bursts of higher-intensity effort helps too.

2. Eat enough protein. Adequate protein is the most critical nutritional factor, and protein deficiency suppresses IGF-1 quickly regardless of how hard you train. A common target is roughly 0.7 to 1.0 gram per pound of body weight daily, spread across the day. Do not crash-diet.

3. Protect deep sleep. GH pulses, and the IGF-1 they generate, happen largely during deep slow-wave sleep. The link is real: people with chronic insomnia have been shown to have markedly lower IGF-1, tracking with how much deep sleep they get. Aim for 7 to 9 quality hours.

4. Reduce visceral fat. Excess belly fat lowers IGF-1 by impairing GH signaling and hepatic function, so losing visceral fat helps restore a healthier axis.

5. Manage stress and cortisol. Chronic stress keeps cortisol elevated, which is catabolic and works against the anabolic effects of IGF-1. A consistent wind-down routine supports the whole system.

6. Cover the basics. Correcting deficiencies in nutrients like zinc and vitamin D, and treating issues like hypothyroidism with your doctor, can meaningfully support IGF-1.

Notice the pattern: these are the same habits that support your muscle, metabolism, recovery, and overall health. That is not a coincidence. Supporting IGF-1 the natural way is mostly just living in a way that keeps your whole system working well.

Can Supplements Raise IGF-1?

Here is the honest answer, because it matters. Oral supplements do not reliably raise blood IGF-1. IGF-1 is a peptide, and like other peptides it is largely broken down during digestion, so swallowing IGF-1 or IGF-1-containing material does not translate into higher blood levels in any dependable way.

Studies on popular natural sources, such as deer or elk antler velvet, have generally found that oral consumption does not meaningfully increase circulating IGF-1. Any product marketed as an oral IGF-1 booster should be viewed with skepticism. The reliable way to support your own IGF-1 is through the training, protein, sleep, and lifestyle levers above.

Where BioPro+ Fits In

If you are building the kind of healthy foundation that supports your whole GH/IGF-1 system, BioPro+ is one option some men consider as part of that bigger picture. It is built on a clear philosophy: support the body's own systems rather than override them.

The formula centers on elk antler velvet extract, a naturally derived source of bioactive proteins, peptides, and amino acids, and pairs it with shilajit, studied for its role in cellular energy and nutrient utilization, plus supportive botanicals. It is a sublingual liquid, easy to take daily, with no needles.

A few honest notes, because trust matters more than hype. BioPro+ is a dietary supplement, not a hormone or a drug, and as covered above, it should not be expected to raise your blood IGF-1, since oral supplements do not reliably do that. It is also worth remembering that more IGF-1 is not the goal anyway, given the U-shaped relationship with health.

What BioPro+ offers is different and worth naming plainly: a non-synthetic, low-risk way to support how you look, feel, and perform as part of a healthy lifestyle built on training, nutrition, sleep, and sound medical care. Think of it as a complement to the fundamentals that genuinely move IGF-1, not a shortcut around them.

These statements have not been evaluated by the Food and Drug Administration. BioPro+ is not intended to diagnose, treat, cure, or prevent any disease.

How Is IGF-1 Measured?

IGF-1 is measured with a simple blood test, and because IGF-1 stays relatively stable through the day, unlike growth hormone, which pulses, it is often used as a practical window into GH activity. Doctors order it when evaluating possible GH deficiency or excess, such as in cases of growth problems in children or acromegaly in adults.

Results are reported against age-adjusted reference ranges, which reflect the normal decline of the axis with age. If you are curious about your own level, ask a clinician, who can interpret it in the context of your age, symptoms, and overall health rather than against a one-size-fits-all target.

Respect the Messenger, Support the System

IGF-1 is the growth factor doing much of growth hormone's real work, driving muscle repair, supporting metabolism, and powering recovery across your body. It declines with age, which helps explain why training feels harder to recover from and muscle gets harder to keep over time. But the smartest approach is not to chase the highest IGF-1 you can get, because both too much and too little carry real risks. The goal is a healthy, age-appropriate level.

The best way to get there is refreshingly ordinary: lift weights, eat enough protein, protect your deep sleep, keep visceral fat in check, and manage stress. These habits support IGF-1 and your overall health at the same time.

Skip the products that promise to spike IGF-1 in a pill, since oral supplements do not reliably do that. If you want a non-synthetic option to support that healthy foundation, BioPro+ is reasonable to consider in its proper place, as a complement to the fundamentals rather than a replacement for them, and check your numbers with a clinician if you want a clearer picture of your own GH/IGF-1 axis.

Frequently Asked Questions

What does IGF-1 do in the body?

IGF-1 is a hormone, made mostly by the liver in response to growth hormone, that carries out much of growth hormone's work. It drives muscle protein synthesis and repair, supports bone and connective tissue, aids recovery and wound healing, has protective roles in nerve and brain tissue, and helps regulate metabolism. It acts on nearly every cell by binding the IGF-1 receptor and switching on growth and repair pathways.

Is high IGF-1 good or bad?

It depends, and balance is key. The relationship between IGF-1 and health is U-shaped, so both very high and very low levels carry risks. Persistently high IGF-1 has been linked to increased risk of certain cancers, while very low IGF-1, especially in older adults, is linked to frailty, muscle loss, and other problems. The goal for most people is a healthy, age-appropriate level, not the maximum.

How can I increase IGF-1 naturally?

The strongest natural levers are resistance training, adequate protein intake (often cited around 0.7 to 1.0 gram per pound of body weight daily), and quality deep sleep, since growth hormone pulses that produce IGF-1 occur mostly during deep sleep. Reducing visceral fat, managing stress and cortisol, and correcting deficiencies in nutrients like zinc and vitamin D also help support healthy IGF-1.

Do IGF-1 supplements work?

Oral supplements do not reliably raise blood IGF-1. IGF-1 is a peptide that is largely broken down in digestion, so swallowing it or IGF-1-containing material does not dependably increase circulating levels. Studies on popular sources like deer and elk antler velvet have generally found no meaningful rise in blood IGF-1 from oral use. The reliable way to support IGF-1 is through training, protein, sleep, and lifestyle.

Why does IGF-1 decline with age?

IGF-1 declines because growth hormone output from the pituitary falls with age, a process called somatopause. Since the liver makes IGF-1 in response to growth hormone, less GH signaling means less IGF-1. On average, IGF-1 drops by roughly 14% per decade after early adulthood, reaching about 30 to 50% of peak levels by age 60 to 70, which contributes to slower recovery and gradual loss of muscle and bone.