Why Most Men’s IGF-1 Is Low (And It Has Nothing to Do With Age)

• Most men in their thirties and forties have IGF-1 levels in the bottom third of the reference range, and almost every one of them has been told by their doctor that this is “normal for your age.” It is not normal in the sense of “healthy and expected.” It is common because almost every man in that age range has the same underlying problems suppressing IGF-1 – and the underlying problems are not age itself.
• Across my client base, the four reproducible drivers of low IGF-1 are visceral fat and insulin resistance, broken sleep architecture, protein inadequacy, and ferritin or vitamin D deficiency. Age is rarely the actual cause of a 35-year-old’s IGF-1 of 120 ng/mL. Age is the excuse the medical system gives for not investigating further.
• The interventions that move IGF-1 meaningfully are lifestyle interventions, not pharmaceutical ones. Sleep architecture restoration, visceral fat reduction, protein adequacy, ferritin repletion, and the right training stimulus. The 6-12-25 Method is the training stimulus I lean on hardest for IGF-1 because of the lactate-driven GH pulse it produces.
• This is not a piece arguing for MK-677 or peptides. This is a piece arguing that the low IGF-1 most men are told to accept is fixable through the same boring sequence of interventions that fixes most of their other hormonal markers.

I want to start by explaining why I have been writing more about IGF-1 over the last year than I have over the previous decade combined. The reason is that the lab numbers I see across new clients have shifted. Total testosterone has gotten more attention from the broader culture, which means men come in with at least a baseline T draw and some understanding of what the number means. IGF-1 has lagged behind. Most men have never had their IGF-1 measured. Of the men who have had it measured, almost none of them know what their number means, what range they should be aiming for, or what is actually driving the number in either direction.

At PowerandBulk.com I have been pulling IGF-1 on every new client for years. The pattern is consistent enough that this article is essentially my standard explanation of what I see, written down so I can stop repeating myself in the first sessions.

What IGF-1 Actually Is

IGF-1 – insulin-like growth factor 1 – is the downstream marker of growth hormone activity in the body. Growth hormone is released in pulses from the pituitary gland, primarily during deep sleep and after specific training stimuli. The growth hormone itself has a short half-life in the blood, which is why measuring GH directly is almost useless – by the time the blood draw happens, the pulse has come and gone. IGF-1 is produced in the liver in response to growth hormone signaling, has a much longer half-life, and serves as the cleanest available proxy for whether your GH system is actually doing its job.

Think of IGF-1 as the GH report card. A blood draw at any point in the day gives you a reasonable picture of how much GH signaling has been happening over the previous days. Low IGF-1 means low GH activity. Low GH activity means slow tissue repair, slower body composition shifts, worse recovery from training, slower skin and connective tissue turnover, and a body that is operating in a partially catabolic state.

The reference ranges most labs use for IGF-1 are age-adjusted, which is the part that I want to push back on. Lab reference ranges for IGF-1 typically span something like 115 to 307 ng/mL for men 31-40, dropping further for older men. The “normal” lower bound for a 35-year-old at most labs is 115, which is the kind of number that gets a “you’re fine” from a GP. In practice, a 35-year-old running an IGF-1 of 115 to 130 is not fine. He is the bottom of a sick population’s distribution. He has the IGF-1 profile of someone whose tissue repair, body composition trajectory, and hormonal cascade are all working below capacity.

Optimal IGF-1 in my client work sits somewhere in the 180 to 250 ng/mL range for most men under 50, with some individual variation. Older men can sit lower and still feel and function well, but the slope of the IGF-1 decline across the lifespan is steeper than it needs to be in almost every man I have worked with.

The Age Argument and Why It Is Mostly Wrong

The standard explanation for low IGF-1 in a 38-year-old is “growth hormone declines with age, this is normal.” It is true that GH and IGF-1 decline with age. The decline is well documented. The problem is that the decline most men experience is dramatically steeper than the underlying age effect would produce in isolation. A 38-year-old with an IGF-1 of 130 is not seeing the natural age decline. He is seeing the natural age decline plus the four big drivers I am about to walk through. Strip those drivers out, and his IGF-1 will land somewhere in the 180-220 range instead of 130. Same age. Different physiological state.

I have seen this play out consistently enough across my client base that “it’s your age” has become one of the medical responses I treat with active suspicion. Age is a permission slip the system gives itself to stop investigating. When I pull a full panel on a man in his thirties or forties with low IGF-1, I find one or more of the four drivers below in essentially every case. Not 80% of cases. Essentially every case.

Driver One: Visceral Fat and Insulin Resistance

Visceral fat – the metabolically active fat that sits inside the abdominal cavity around the organs, distinct from the subcutaneous fat under the skin – directly suppresses growth hormone release. The mechanism is established. Visceral adipose tissue interferes with GH secretion at the pituitary and reduces GH pulse amplitude during sleep. Higher visceral fat equals lower GH output equals lower IGF-1.

The insulin piece is the same problem from a different angle. Elevated insulin acutely suppresses GH release. A man with chronically elevated fasting insulin – anything above eight or so – is operating with a GH system that is being suppressed every time he eats and never fully releases the way it should. The chronically high postprandial insulin pattern of someone with metabolic syndrome or pre-metabolic syndrome blunts GH pulses across the entire day.

Trevor Halsey was a clean example of this. He came to me at 36, total T 540, IGF-1 138. Looked lean. His issue was not visible obesity. His issue was subclinical metabolic dysfunction – fasting insulin 11, HbA1c 5.5, triglyceride-to-HDL ratio 3.8. After six months of the protocol I run (which I detailed in the four-things-before-supplements piece), his fasting insulin dropped to 6, his triglyceride-to-HDL ratio dropped to 1.5, and his IGF-1 climbed to 186. He had not added any GH-targeting supplement. The IGF-1 climbed because the metabolic suppression was lifted.

Wesley Cardwell, whose 280-to-740 testosterone protocol I walked through in the lifestyle stack article, was a more extreme version of the same pattern. His IGF-1 at baseline was 108. By month six, after the metabolic and visceral fat work, his IGF-1 was 192. Same age. Same person. Different physiological state. The metabolic recovery was the IGF-1 lever.

Driver Two: Broken Sleep Architecture

Seventy to eighty percent of daily growth hormone is released during slow-wave sleep – the deep sleep stages that dominate the first half of the night. A man whose sleep architecture is broken is missing most of his daily GH production, regardless of how many total hours of sleep he is getting.

This is the part of the IGF-1 puzzle that the medical system almost never investigates. The standard low-IGF-1 conversation does not include “have you had a sleep study.” It should. In my client base, men with low IGF-1 frequently have undiagnosed sleep apnea, fragmented sleep from alcohol use, or the kind of insufficient deep sleep that comes from chronic blue light exposure before bed, late caffeine, or a stress pattern that keeps cortisol elevated through the first half of the night.

Doug Sterling came to me at 52 after a brutal divorce. Total T 310, IGF-1 102, drinking too much, sleep wrecked. His IGF-1 was being suppressed by three things simultaneously: visceral fat from weight gain, alcohol fragmenting the second half of his sleep, and almost zero deep sleep during the first half because of a cortisol pattern that had been broken for a year. Over the protocol, we addressed each in sequence. Alcohol came down to zero. Sleep architecture restored over four months. By month nine his IGF-1 was 174. By month fourteen it was 198, with a total T of 680. Same Doug. Different physiological state.

The student piece on the correlation between deep sleep minutes and IGF-1 tracked this relationship in detail. The math is direct. More deep sleep equals higher IGF-1. The interventions that drive deep sleep – cool bedroom, dark room, no alcohol, magnesium glycinate, glycine, no late caffeine, screen cutoff – drive IGF-1 indirectly but reliably.

Driver Three: Protein Inadequacy

IGF-1 is sensitive to protein intake in a way most men do not appreciate. The liver produces IGF-1 in response to GH signaling, but the production also requires adequate amino acid substrate. A man eating 80 grams of protein a day at 190 pounds is providing the substrate for sub-optimal IGF-1 production even if his GH signaling is intact. Protein restriction studies in healthy adults consistently show IGF-1 declines under chronic protein inadequacy.

The threshold matters. The 0.36 g/kg RDA most men have heard from somewhere is a survival number, not an optimization number. For IGF-1 maintenance and for the broader hormonal cascade, the range I push clients toward is 1.6 to 2.2 grams of protein per kilogram of bodyweight, distributed across three or four meals, with each meal hitting the leucine threshold of roughly 2.5 to 3 grams.

I have seen IGF-1 move 30 to 50 ng/mL across three to four months on protein adequacy alone in men who came in eating somewhere between 90 and 130 grams a day at bodyweights above 180 pounds. The intervention is not complicated. It is the application of consistent protein adequacy to a body that has been under-fueled for years.

Wesley’s protein intake at baseline was somewhere in the 100 to 120 gram range despite being 245 pounds. After we restructured his food, he was hitting 180 to 200 grams a day. The protein adequacy was downstream of the food cleanup but did its own independent work on his IGF-1 trajectory.

Driver Four: Ferritin and Vitamin D Deficiency

This is the driver most often missed. Ferritin and vitamin D both function as upstream inputs to the GH-IGF-1 axis in ways that are not obvious from the surface.

Ferritin is the iron storage protein. Iron is required for the hepatic enzymes that produce IGF-1. Low ferritin – I see this commonly in men under 60 ng/mL, optimal is somewhere in the 80 to 200 range for men – suppresses IGF-1 production at the liver. The relationship is direct. The student piece on a low-ferritin correction case showed an IGF-1 climb of 28 ng/mL just from getting ferritin from 28 up to 95 over four months. No other interventions, no GH-targeting work, just iron repletion.

Vitamin D operates as a hormone – I made the full argument for this in the vitamin D piece – and one of the things it does is modulate GH receptor sensitivity in peripheral tissues. A man with vitamin D at 18 ng/mL is operating with reduced GH receptor activity throughout his body. Correcting vitamin D to the 50+ range improves the entire system’s response to whatever GH signaling is happening.

The reason I list these together as a single driver is that they often present together. The man with ferritin at 35 frequently has vitamin D at 22. The two deficiencies cluster because they are both downstream of the same dietary and lifestyle patterns. Correcting both at once, which I do as part of the standard early-protocol micronutrient work, often produces a meaningful IGF-1 climb before any other intervention has time to land.

The Training Stimulus That Actually Moves IGF-1

I want to talk about training here because most of the training men are doing in commercial gyms is not producing meaningful IGF-1 response. Steady-state cardio does not. Light resistance work does not. Pure strength work at low rep ranges produces testosterone response but not much GH response. To drive IGF-1 through training, you need a stimulus that drives blood lactate above the lactate threshold during the session. This is the part of the physiology that the 6-12-25 Method is specifically built around.

The 6-12-25 Method – which I walk through in detail in the 6-12-25 Method authority piece and in the mechanics explainer – drives blood lactate well above threshold via the twenty-five-rep finisher. The relationship between blood lactate accumulation and acute GH release is one of the more durable findings in exercise endocrinology. Workouts that drive lactate produce GH pulses that low-lactate workouts do not produce, at equivalent total work.

Across the sixty or so clients I have run on 6-12-25 for at least six months, the IGF-1 improvement averages somewhere in the 40 to 70 ng/mL range. That is a substantial move, and it sits on top of whatever IGF-1 gains the metabolic, sleep, protein, and micronutrient work has already produced. The training stimulus is one lever among several, but it is one of the more reliable ones once the recovery context supports it.

What I Do Not Lean On

I want to be clear about what I am not doing here. I am not running clients on MK-677 (Ibutamoren) as a default intervention. I have written more nuance on that compound in the supplement tier list – it does raise IGF-1 reliably, but it comes with insulin resistance, water retention, leptin sensitivity issues, and a dependency pattern that I do not think most men should take on without understanding the trade-off. I am not running clients on sermorelin, tesamorelin, or other GH secretagogues unless there is a specific clinical context that supports it. Most men do not need exogenous GH support. They need the four drivers above corrected.

The arginine and ornithine stack that gets sold as a “natural GH booster” does almost nothing meaningful at oral doses in healthy adults. The clinical studies that support the claim used intravenous administration or doses that produce severe GI distress at oral doses. The supplement industry has built a marketing position around studies that do not translate to the dosing customers are taking.

Glycine has more support than arginine for sleep-driven GH release – it acts on deep sleep architecture and there is reasonable evidence that 3 grams before bed improves sleep quality and the GH pulse during early sleep. I use glycine selectively for clients who need sleep architecture work, not as a generic GH booster.

The Protocol I Run

The protocol I run for low IGF-1 is the same protocol I run for most hormonal optimization work, sequenced specifically. I will lay it out plainly.

Month one and two: food cleanup, walking, vitamin D and magnesium correction. The metabolic foundation. No training changes, no other supplements.

Month two and three: sleep audit, sleep study if indicated, alcohol audit. Resolve sleep apnea, broken architecture, late caffeine, screen exposure. Add glycine before bed if architecture is the limiting factor.

Month three to four: protein adequacy push. Get the man to 1.8 to 2.2 g/kg distributed across three or four meals. This often requires changing how he plans his food, not just adding a shake.

Month four: introduce strength training if it is not already running. Conservative volume to start. Build to the 6-12-25 Method by month five or six.

Month five and onward: targeted micronutrient stack as needed – boron, zinc, additional vitamin D if levels have not climbed – and the full training stimulus. Pull bloodwork at month six.

Across this protocol, IGF-1 improvements of 50 to 80 ng/mL across six months are common. Sometimes 100+. The men who are starting from the worst baseline see the biggest moves, which is the same pattern that shows up in testosterone work. The body wants to return to a healthy state when you stop suppressing it.

What “Normal for Your Age” Actually Means

If you take one thing from this article, let it be this. “Normal for your age” is a sentence about the population, not about you. The population is sick. The population has visceral fat. The population has broken sleep. The population is under-fueled on protein. The population has unrecognized deficiencies. Being normal in that population means being the average member of a population whose hormonal output is below capacity.

You do not have to accept that baseline. The IGF-1 of a 42-year-old is not fated to sit at 135 because he is 42. The IGF-1 of a 42-year-old sits at 135 because of the four drivers above, in some combination. Correct the drivers and the IGF-1 climbs. Same age. Different physiology.

I have not seen a single case in my client work where the cause of low IGF-1 in a man under 55 turned out to be “just age.” Every case I have investigated has had one or more of the four drivers running underneath it. The drivers are fixable. The IGF-1 follows.

This sequence is built into the Anabolic Alchemy program because IGF-1 is one of the markers I track on every client throughout their work with me. It is one of the cleaner objective signals that the protocol is producing the cascading physiological changes the rest of the work is built to produce. Testosterone gets the headlines. IGF-1 is often the marker that moves first.

If you are reading this with a recent IGF-1 number in front of you and the number is low, you are not seeing the natural consequence of your age. You are seeing the cumulative consequence of the four drivers above. The work is the same work I have written about everywhere else on this site. The result, in six to twelve months, is an IGF-1 that looks like a healthy man’s IGF-1 should look at your age. The age was never the problem. The conditions underneath the age were the problem. Fix the conditions.