Summary
Highlights
IGF-1 (Insulin-like Growth Factor 1) is a powerful anabolic growth factor naturally produced by the body, primarily in the liver in response to growth hormone. It promotes muscle growth, improves recovery, and enhances fat metabolism. It can also be produced locally in muscles as 'mechano growth factor' in response to mechanical stress like weightlifting. IGF-1 plays a crucial role in anabolic signaling pathways, inhibits myostatin (a muscle growth limiter), and stimulates satellite cells for muscle repair and growth. It also reduces muscle protein breakdown.
Beyond muscle, IGF-1 is vital for bone growth and density, especially during puberty for height development, and supports bone remodeling in adults. It also improves insulin sensitivity, increases fat metabolism, enhances thymus function (an immune organ), improves skin health, and protects mitochondria.
Natural optimization of IGF-1 involves several factors. Insulin can enhance growth hormone receptor sensitivity, making post-workout meals with carbs and protein beneficial. Resistance training, particularly high-intensity, high-volume workouts, significantly boosts growth hormone and subsequently IGF-1. Deep sleep, achieved through a regular sleep schedule, exposure to natural light, consistent meal times, and avoiding blue light before bed, is critical for growth hormone release. Managing stress to keep cortisol levels low is also important as high cortisol inhibits IGF-1 production. Maintaining thyroid health and liver health contributes to optimal IGF-1 levels.
Certain foods and supplements can increase IGF-1. Amino acids like arginine and leucine, abundant in eggs, meat, fish, dairy, and bone broth, boost growth hormone. Sufficient protein intake, especially animal protein, is strongly correlated with height and IGF-1. Avoiding chronic caloric deficits or excessive long-term fasting is also advised. Specific foods like milk and eggs are powerful for IGF-1. Essential minerals include zinc (from beef, oysters) and magnesium (recommended as a supplement). Creatine and BCAAs indirectly support IGF-1 by enhancing training and recovery. Vitamin D, ideally from midday sunlight or supplements, and other foods like blueberries, Vitamin C, and ecdysteroids (quinoa, spinach) are also beneficial.
While natural optimization is beneficial, excessively high IGF-1 levels are rare and usually occur due to genetic conditions, hyperthyroidism, chronic overfeeding with animal protein, or exogenous IGF-1 use. Risks of high IGF-1 include low blood sugar, acne, organ growth, and increased cancer risk. Conversely, low IGF-1 levels are linked to frailty, poor recovery, and increased mortality. The goal is a naturally optimized, ideal middle-ground level.
The most important strategies for increasing IGF-1 naturally are deep sleep, resistance training, consuming plenty of protein and amino acids (especially animal protein), managing stress, timing a significant insulin spike post-workout with carbs and protein, and including foods like milk, eggs, meat, and fish. Supplementing with creatine, ensuring adequate vitamin D, zinc, and magnesium also plays a vital role.