What is IGF-1 and Why It Matters
Insulin-like Growth Factor 1 (IGF-1) is a hormone primarily produced in the liver in response to growth hormone. It plays a crucial role in cell growth, muscle and bone maintenance, and even brain function. IGF-1 also influences aging and longevity. In fact, both high and low IGF-1 levels have been linked to higher risk of death from all causes, forming a U-shaped curve of mortality risk (1). Yet despite these profound connections to healthspan, IGF-1 is rarely included in routine bloodwork. Most doctors only check IGF-1 when evaluating pituitary disorders (like growth hormone deficiency or acromegaly) and typically ignore it in otherwise “healthy” adults (2). This oversight means many people have no idea where their IGF-1 stands—or that it could be the missing piece in their longevity puzzle.
💡 Key Takeaway: IGF-1 is one of the most overlooked yet powerful predictors of how you age—and it’s not on most standard lab panels.
IGF-1 as a Longevity Marker
Research over the past decade has solidified IGF-1’s reputation as a key biomarker of aging. Lower IGF-1 activity has been associated with lifespan extension in animal models, but in humans the story is more nuanced. Extremely low IGF-1 can lead to frailty and cognitive decline, whereas very high IGF-1 can fuel age-related diseases (3). The trick is finding the “Goldilocks zone”—an IGF-1 range that is neither too high nor too low, supporting healthy aging and minimizing disease risk.
IGF-1, Aging, and All-Cause Mortality
Multiple studies have explored how IGF-1 levels relate to lifespan. A 2022 meta-analysis of 19 cohort studies (over 30,000 participants) found a clear U-shaped relationship: people with IGF-1 in the ~120–160 ng/mL range had the lowest risk of death from any cause (1). In contrast, those with higher IGF-1 or much lower IGF-1 had significantly increased mortality risk. Similarly, a 2023 prospective study reported that individuals with either very low or very high IGF-1 were more likely to die from cancer, cardiovascular disease, or any cause, compared to those in the middle ranges (2).
💡 Key Takeaway: Staying in the mid-range for IGF-1—between 120 and 160 ng/mL—may significantly reduce your risk of premature death.
IGF-1 Levels Decline with Age
IGF-1 tends to peak in puberty and early adulthood, then steadily decline with age (4). One reference range study showed median IGF-1 levels around 180 ng/mL at age 35, but only ~93 ng/mL by age 70. While some people remain high due to diet or metabolic dysfunction, others fall below optimal longevity ranges without knowing it (5).
High IGF-1: Elevated Levels and Cancer Risk
IGF-1 promotes cell proliferation, which is beneficial in tissue repair but risky when it comes to cancer. In the EPIC-Heidelberg study, individuals in the highest quintile of IGF-1 had a 25% higher risk of breast cancer and a 31% higher risk of prostate cancer (2). Elevated IGF-1 also activates growth pathways (PI3K-Akt, Ras-MAPK) that may allow tumor cells to escape apoptosis (cell death) (3).
💡 Key Takeaway: High IGF-1 might help build muscle—but it also increases your risk of cancer and cardiovascular mortality.
Want a clear, effective path to sustainable fat loss?
Sign up for the PlateauBreaker™ Plan and start your fat-loss journey today.
Low IGF-1: Frailty and Cognitive Decline
Low IGF-1 has its own risks. In aging populations, low IGF-1 is strongly associated with:
- Sarcopenia and muscle loss
- Frailty and slower walking speed
- Reduced bone density
- Increased risk of disability and cognitive decline (6)(7)
In a Japanese study, older adults in the lowest quartile of IGF-1 had a 72% higher risk of becoming disabled within 2.5 years (7).
💡 Key Takeaway: If IGF-1 falls too low, it can accelerate physical decline, cognitive impairment, and frailty.
Why Doctors Don’t Routinely Test IGF-1
Even though IGF-1 is crucial for longevity, most primary care physicians don’t test for it. That’s partly because:
- It’s traditionally used only for diagnosing GH disorders
- Reference ranges are wide and age-dependent
- Insurance may not cover it
- Many doctors simply aren’t aware of its longevity implications (2)(4)
💡 Key Takeaway: You may need to request IGF-1 testing yourself—and be prepared to explain why it matters.
The Ideal IGF-1 Range for Midlife Adults
Most evidence suggests that 120–160 ng/mL is the longevity sweet spot for midlife adults (1). Staying in this range supports:
- Muscle and bone maintenance
- Lower cancer and cardiovascular risk
- Better cognitive function
- Healthy cellular aging
💡 Key Takeaway: If you’re in your 40s, 50s, or 60s, aiming for IGF-1 between 120 and 160 ng/mL may help you age better—and longer.
Lifestyle Strategies for Optimizing IGF-1 Naturally
You don’t need medication to balance IGF-1. In most people, lifestyle is the key driver. These evidence-backed strategies can help:
- Intermittent Fasting (IF)
Fasting reduces liver IGF-1 production by lowering insulin and nutrients. A systematic review showed IF lowered IGF-1 by about 29 ng/mL (8). - Moderate Protein Intake
High animal protein increases IGF-1. In one study, middle-aged adults on a high-protein diet had four times the cancer death risk—linked to elevated IGF-1 (9). Reducing protein or emphasizing plant sources brought IGF-1 down ~30%. - Cut Refined Sugar and Carbs
Insulin can influence IGF-1 bioavailability. A low-sugar, high-fiber diet improves insulin sensitivity and balances the GH–IGF axis (10). - Regular Moderate Exercise
Resistance training boosts low IGF-1. In one 24-month study, older women who lifted weights improved both IGF-1 and cognition (11). - Maintain a Healthy Weight
Obesity suppresses IGF-1 even though insulin is high. Weight loss (especially visceral fat) often raises low IGF-1 toward optimal (12)(13).
💡 Key Takeaway: Fasting, moderate protein, smart exercise, and body composition all work together to move IGF-1 into the optimal range.
✏︎ The Bottom Line
IGF-1 may be the most important longevity biomarker that you’re not measuring. Research shows that mid-range IGF-1 levels (~120–160 ng/mL) are linked to lower risk of cancer, frailty, and early death. Yet most doctors don’t test it, and most people don’t know it exists.
But now you do.
If you’re serious about optimizing how you age, ask your provider to test IGF-1 and adjust your lifestyle accordingly.
👉 Want to understand how your hormones and bloodwork affect fat loss and aging?
Download our free eBook
10 Weight Loss Myths That Are Keeping You Stuck – And How to Break Free
References
- Rahmani, Jamal et al. “Association between IGF-1 levels ranges and all-cause mortality: A meta-analysis.” Aging cell vol. 21,2 (2022): e13540. doi:10.1111/acel.13540. https://pubmed.ncbi.nlm.nih.gov/35048526/
- Mukama, Trasias et al. “IGF-1 and Risk of Morbidity and Mortality From Cancer, Cardiovascular Diseases, and All Causes in EPIC-Heidelberg.” The Journal of clinical endocrinology and metabolism vol. 108,10 (2023): e1092-e1105. doi:10.1210/clinem/dgad212. https://pubmed.ncbi.nlm.nih.gov/37066827/
- Yamaguchi, Ryuji et al. “VHL-deficient renal cancer cells gain resistance to mitochondria-activating apoptosis inducers by activating AKT through the IGF1R-PI3K pathway.” Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicinevol. 37,10 (2016): 13295-13306. doi:10.1007/s13277-016-5260-2. https://pubmed.ncbi.nlm.nih.gov/27460078/
- Bidlingmaier, Martin et al. “Reference intervals for insulin-like growth factor-1 (igf-i) from birth to senescence: results from a multicenter study using a new automated chemiluminescence IGF-I immunoassay conforming to recent international recommendations.” The Journal of clinical endocrinology and metabolism vol. 99,5 (2014): 1712-21. doi:10.1210/jc.2013-3059. https://pubmed.ncbi.nlm.nih.gov/24606072/
- Bartke, A et al. “Insulin-like growth factor 1 (IGF-1) and aging: controversies and new insights.” Biogerontology vol. 4,1 (2003): 1-8. doi:10.1023/a:1022448532248. https://pubmed.ncbi.nlm.nih.gov/12652183/
- Westwood, Andrew J et al. “Insulin-like growth factor-1 and risk of Alzheimer dementia and brain atrophy.” Neurologyvol. 82,18 (2014): 1613-9. doi:10.1212/WNL.0000000000000382. https://pubmed.ncbi.nlm.nih.gov/24706014/
- Doi, Takehiko et al. “Insulin-Like Growth Factor-1 Related to Disability Among Older Adults.” The journals of gerontology. Series A, Biological sciences and medical sciences vol. 71,6 (2016): 797-802. doi:10.1093/gerona/glv167. https://pubmed.ncbi.nlm.nih.gov/26424830/
- Rahmani, Jamal et al. “The influence of fasting and energy restricting diets on IGF-1 levels in humans: A systematic review and meta-analysis.” Ageing research reviews vol. 53 (2019): 100910. doi:10.1016/j.arr.2019.100910. https://pubmed.ncbi.nlm.nih.gov/31116995/.
- Levine, Morgan E et al. “Low protein intake is associated with a major reduction in IGF-1, cancer, and overall mortality in the 65 and younger but not older population.” Cell metabolism vol. 19,3 (2014): 407-17. doi:10.1016/j.cmet.2014.02.006. https://pubmed.ncbi.nlm.nih.gov/24606898/
- Burris, Jennifer et al. “A Low Glycemic Index and Glycemic Load Diet Decreases Insulin-like Growth Factor-1 among Adults with Moderate and Severe Acne: A Short-Duration, 2-Week Randomized Controlled Trial.” Journal of the Academy of Nutrition and Dietetics vol. 118,10 (2018): 1874-1885. doi:10.1016/j.jand.2018.02.009. https://pubmed.ncbi.nlm.nih.gov/29691143/
- Jiang, Qiang et al. “The effect of resistance training on serum insulin-like growth factor 1(IGF-1): A systematic review and meta-analysis.” Complementary therapies in medicine vol. 50 (2020): 102360. doi:10.1016/j.ctim.2020.102360. https://pubmed.ncbi.nlm.nih.gov/32444042/.
- Mason, Caitlin et al. “Effects of dietary weight loss and exercise on insulin-like growth factor-I and insulin-like growth factor-binding protein-3 in postmenopausal women: a randomized controlled trial.” Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology vol. 22,8 (2013): 1457-63. doi:10.1158/1055-9965.EPI-13-0337. https://pmc.ncbi.nlm.nih.gov/articles/PMC3732802/#:~:text=Greater%20weight%20loss%20was%20positively,(ptrend%3D0.01).
- Rasmussen, M H et al. “The impact of obesity, fat distribution, and energy restriction on insulin-like growth factor-1 (IGF-1), IGF-binding protein-3, insulin, and growth hormone.” Metabolism: clinical and experimental vol. 43,3 (1994): 315-9. doi:10.1016/0026-0495(94)90099-x. https://pubmed.ncbi.nlm.nih.gov/7511202/
