The Protein Paradox: Too Much or Too Little Protein Can Cause Problems

In 2003 a new weight loss fad began emerging—high protein diets. For a while, these high-protein, low-carb diets seemed like the Holy Grail of weight loss.

Over time, many people found these diets difficult to sustain and associated with some health issues. The diets fell out of favor as a lifestyle but were still used as a quick weight-loss strategy. Yet, in the wake of high-protein diet heyday, many Americans were left with a sense that a high protein and low carbohydrate diet is healthy.

Eating Too Much Protein

Your body needs protein to build and repair muscles, bones, hair, skin, blood vessels, fingernails and organ tissue. It plays a role in just about every action in your body. So logically, more protein is better, right? Not necessarily.

Eating too much protein can cause unnecessary stress on the kidneys. And some researchers link too much protein—specifically, the amino acids (protein building blocks) methionine and leucine—with a shorter lifespan.

Methionine is found in high-protein foods such as meat, fish, poultry, eggs, dairy products and nuts. It helps your body create a very powerful antioxidant (glutathione) and plays a crucial role in developing new blood vessels. But your body also uses it to create another amino acid, homocysteine. High blood levels of homocysteine are associated with a long list of chronic diseases including cardiovascular disease, diabetes and cancer.

Too much dietary protein can also raise insulin-like growth factor or IGF-1 levels. You need IGF-1 as child for normal growth and development. But after puberty, IGF-1 levels wane. And as adults, too much IGF-1 levels seems to raise the risk for numerous types of cancers.

Finally, too much protein stimulates mTOR (or mechanistic target of rapamycin). This is a "sensor" every cell has that tells it to either repair itself or reproduce. Since our cells are constantly bombarded with free radicals that damage them, it’s better to have a slower mTOR that will instruct a cell to fix itself before reproducing.

When damaged cells reproduce, it raises the risk of disease. High mTOR levels have been linked to virtually every type of cancer and rapamycin is commonly used as a chemotherapeutic drug.

How Much Protein Do You Need?

Should you limit your protein intake? It depends. Athletes trying to build muscle mass, children and teenagers who are growing and older adults who are losing muscle mass need a little more protein. But you probably need less than you think.

The general rule of thumb is to eat 0.8 grams of protein per day per kilogram of body weight, or 0.36 grams per pound. If you’re an athlete, you may need a little more.

Want to optimize your protein intake to your body type? Use this formula to help you determine your specific protein needs. You'll need to know your body fat percentage, which your MDVIP-affiliated physician can give you.

• Subtract body fat percentage from 100. Divide the result by 100.

• Multiply the result by your weight in pounds. This will give you your lean body weight.

• Convert your lean body weight into kilograms (1 lb = 0.45 kg).

• Finally, multiply this number by 0.8. The result is the amount of grams of protein a day you should aim for.

Here’s an example: A 150-pound woman with 15 percent body fat would net out at 45.9 grams of protein a day (100-15=85; 85/100=0.85; 150*0.85=127.5 lbs; 127.5*0.45=57.8; 57.8*0.8 = 45.9 g).

If you don’t know your body composition, check with your MDVIP-affiliated physician. They may be able to help you. Many MDVIP-affiliated physicians measure your body composition as part of the MDVIP Wellness Program.

For my patients with prediabetes, high insulin, weight gain or diabetes, I recommend a simple approach to protein:

• Less than 100 grams of carbohydrates per day
• Less than 100 grams of protein per day
• Other calories come from fat. It may sound strange but in my opinion, based on all the literature I have read, a high fat diet is very likely an important key to longevity.

To see where you stack up on carbs and protein, you can visit Cronometer’s website at https://cronometer.com. Just remember to subtract your fiber from total carbohydrates for your net carbohydrate intake.

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This blog reflects the medical opinion of Dr. Lou Malinow, an MDVIP-affiliated internist, board-certified hypertension specialist and Diplomate of the American Board of Lipidology, and not necessarily the opinion of all physicians in the MDVIP national network.

This content was last reviewed November 2020.