What happens when you eat too much protein — and how to figure out the healthiest amount for you

Too much protein can be a real missed steak.

While protein is essential for muscle maintenance and overall health, overdoing it can come with some serious risks and side effects.

“Consuming excessive protein, particularly from animal sources, raises insulin-like growth factor 1 (IGF-1) levels,” Dr. Joseph Antoun, CEO of the longevity company L-Nutra, told The Post.

IGF-1 is a hormone, primarily produced in the liver, that plays a crucial role in promoting growth and regulating metabolism.

“While it’s essential in childhood and for muscle repair,” Antoun said, “chronically elevated IGF-1 in adults has been linked to accelerated biological aging and therefore an increased risk of age-related conditions, notably cancer.”

Promoting cellular growth while neglecting repair increases the risk of DNA mutations, which can lead to certain cancers, Type 2 diabetes and cardiovascular disease.

Antoun calls chronically elevated IGF-1 the “diabetes of protein,” because it “excessively ages the body way beyond what the muscles require.”

So, how much protein is too much?

It depends on your age and goals. If you’re younger than 65, Antoun suggests aiming for 0.31 to 0.36 grams of plant-based protein per pound of body weight daily.

For reference, that would be 46.5 to 54 grams of protein for someone weighing 150 pounds — or roughly seven large eggs, 200 grams of chicken breast or 2 cups of cooked lentils.

“If you are over 65 years of age, increase protein intake slightly if you are losing muscle or weight,” he advised.

“For individuals over 65 experiencing muscle, strength or weight loss, increasing protein from sources such as fish, eggs, cheese and yogurt made from sheep or goat milk is recommended.”

As for trendy all-meat regimens like the carnivore diet? Antoun’s take is that it can be well done, but that’s rare.

“There are significant long-term risks with following the carnivore diet,” he said.

“High IGF-1 levels and high consumption of saturated fats are associated with increased risk of heart disease and many cancers, such as colorectal cancer. Additionally, the absence of fiber — a fundamental component for gut health — can lead to dysbiosis, inflammation and increased susceptibility to chronic diseases like inflammatory bowel disease and diverticulitis.”

He added that eliminating fruits, vegetables and other plant-based foods can deprive your body of essential antioxidants and nutrients, which are crucial for a long, healthy life.

“While some individuals may see short-term benefits from eliminating highly processed foods in favor of whole foods, adopting an all-meat diet is not a sustainable or health-promoting solution,” Antoun said.

“Those with severe autoimmune conditions or digestive issues who are experimenting with elimination diets may find temporary relief, but long-term reliance on such an extreme approach is not supported by science.”

Instead, he recommends a “well-balanced, plant-forward approach” that is “rich in complex carbs, plant-based/fish-based proteins and healthy fats from nuts and seeds,” pointing to ample evidence that it’s what’s best for longevity.

“When we study centenarians, we notice that most of them follow a plant-based Mediterranean, pescatarian or flexatarian diet and fast a few times per year for cultural or religious reasons,” he said.

And if you’re still unsure you’re meeting your protein needs, you might want to consider getting your IGF-1 levels checked at your next doctor’s appointment.

Antoun pointed to recent research indicating the optimal IGF-1 rate is between 130 and 160.

“Below 130 IGF-1, more proteins are needed for muscle; above 160, and the body is aging faster than ideal,” explained Antoun, whose L-Nutra developed a plant-based protein powder designed to support muscle health without accelerating aging.

So, the next time you saddle up for steak night, proceed with caution.

The goal isn’t to just build muscle — it’s to live long enough to use it.