Key Takeaways

• Overconsumption of animal-based protein raises IGF-1 levels—a growth hormone linked to increased risk of chronic disease, accelerated aging, and reduced cellular repair.
• While IGF-1 is essential in youth and for muscle repair, chronically elevated levels in adulthood can disrupt longevity by promoting cell growth over cellular cleanup (autophagy).
• Experts recommend a Mediterranean or flexitarian approach—favoring plant- and fish-based proteins over heavy meat consumption—to reduce IGF-1 and support long-term health.

Protein is an essential nutrient for optimal health. And between the variety of meats, eggs, beans, nuts, and so much more to choose from, there are a lot of options when it comes to sourcing protein. Unfortunately, though, an overconsumption of protein can actually sabotage your longevity efforts, says healthy aging expert Joseph Antoun. “Consuming excessive protein, particularly from animal sources, raises IGF-1 levels,” he says. “IGF-1, Insulin-like Growth Factor 1, is a hormone that plays a crucial role in growth and cell proliferation.”

But what’s the science behind the negative effects of eating too much protein? How is IGF-1 affected? We asked our longevity experts all the questions—including the best approach to eating the right amount of protein.

How Does IGF-1 Affect Our Longevity, Exactly?

“Excessive IGF-1 is harmful to healthy longevity, as it promotes cellular growth over repair (increasing the risk of mutations), decreases autophagy (the cellular cleanup process key to healthy aging), and increases risk of chronic diseases,” Antoun says. Foods that are high in animal protein—such as meat, eggs, and even milk—stimulate and increase our IGF-1 levels, meaning the more you eat, the more you’re at risk of increased IGF-1 levels.

“While it’s essential in childhood and for muscle repair, chronically elevated IGF-1 in adults has been linked to accelerated biological aging, and therefore, an increased risk of age-related conditions,” Antoun says. “I call this condition the ‘Diabetes of Protein,’ whereby high IGF is excessively aging the body way beyond what the muscles require.” You might notice these lasting impacts on excessively muscular figures, such as body builders, who look great during their peak but tend to age poorly in their 50s and 60s. Much like when you’re a kid, eating animal-based protein in your 20s can feel and seem healthy, Antoun notes. Around the mid-life period, however, disease formation begins and can slow down the natural processes of our body.

You might be wondering what exactly you can eat to get your recommended daily intake of protein. Don’t worry—we’ve got you covered.

What’s the Best Way to Eat Protein?

“A well-balanced, plant-forward approach, such as a longevity-based diet(rich in complex carbs, plant-based/fish-based proteins, and healthy fats from nuts and seeds) offers a far more evidence-based path to metabolic health, disease prevention, and healthspan,” Antoun says. “When we study centenarians, we notice that most of them follow a plant-based Mediterranean, pescatarian, or flexitarian [semi-vegetarian] diet.”

Rather than quitting cold turkey, it’s best to slowly replace animal protein with plant-based protein without completely giving up meat or eggs. For example, you might turn your weekly grilled chicken rotation into a salad, where you’re getting more diverse nutrients than just animal protein. If you tend to eat a specific meat the most, consider replacing it with a plant-based protein like tofu, so you’re still getting the same textural experience while managing your IGF-1 levels. “A pure vegan diet is also correlated with longevity, but it needs to be supplemented with protein—especially at early and late stages of life,” Antoun adds. Like most things, consumption of animal protein in moderation can be a small change that makes a big difference.

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