Why We Need More Protein as We Age

When we think about protein, we tend to think of it as a tool to build muscle — and that’s certainly a priority for the aging body. Protein is key to preventing the loss of lean muscle mass as we age, known as sarcopenia.

But proteins are more versatile than we might think. “Proteins are the master regulators of all that is happening in your body, controlling function in all tissues and organs, including muscle,” explains Gabrielle Lyon, MD, in her book Forever Strong. “They include enzymes — a class of proteins that catalyze all the chemical reactions within the body. Proteins also support energy production and cell-to-cell communication.”

In other words, these hard-working macronutrients help us maintain healthy bones, strengthen our immune system, improve our metabolism, and boost our mood. And, by promoting satiety, they keep us from overeating.

Yet most of us — especially seniors — don’t consume nearly as much protein as we need for optimal health.

A study published in 2020 found that as many as 30 percent of older Americans don’t meet the recommended dietary allowance (RDA) of protein (0.36 grams per pound of body weight), and as many as 76 percent fall short of the more optimal goal of 0.54 grams per pound of body weight.

The RDA, Lyon reminds us, doesn’t account for active lifestyles and the need to protect muscle mass as we age. She and other experts recommend that adults consume 30 to 50 grams of protein at each meal. For those who are working out regularly, 1 gram of protein per pound of goal body weight per day is a common recommendation.

 

Proteins Have Their Priorities

Skimping on protein forces the body to make hard choices, and those decisions always favor survival — protecting the most vital organs at the expense of muscle.

“A body trying to make do with a low-protein diet will prioritize the survival of the liver, heart, brain, kidney, and gastrointestinal tract,” Lyon explains. “Eating only enough protein to fuel these essential functions will leave your body lacking sufficient amino-acid supply to support skeletal-muscle growth and repair.”

Our protein needs only increase over time as our muscles lose their ability to sense and respond to low doses of amino acids. The resulting tissue destruction can begin at any age, Lyon says, but it’s generally detectable by our 40s. Ironically, that’s also when many of us begin to reduce our physical activity, thus exacerbating the problem.

“A body trying to make do with a low-protein diet will prioritize the survival of the liver, heart, brain, kidney, and gastrointestinal tract.”

“It’s a Catch-22, really,” notes Paul Kriegler, RD, director of nutrition product development at Life Time. “It’s harder to maintain just because our biology slows down a little bit, and we tend to accelerate the loss of lean tissue and strength if we don’t use it.”

At a cellular level, what changes as we age are the forces that trigger a mechanism known as the mammalian target of rapamycin (mTOR). mTOR, which promotes the protein-synthesis process that builds muscle tissue, is regulated in our youth by hormones (insulin, growth hormone, IGF-1, etc.) that gradually become less effective as our skeletal muscle develops more anabolic resistance to them. At that point, the body becomes more dependent on leucine, an amino acid only protein can deliver. Leucine activates a component of the mTOR signal complex that helps initiate and sustain protein synthesis within cells.

“Think of leucine as the key you turn or the button you push in your car to fire up the engine,” Lyon explains. “mTOR is the engine, and all the amino acids your body has available supply the fuel.”

 

Plants or Animals?

Lyon touts leucine, methionine, and lysine as the most important amino acids for building muscle. And though some plants are good sources of methionine and others offer more leucine and lysine, only animal proteins deliver optimal amounts of all three.

“Extensive research shows that the highest-quality proteins come from animal sources, including meats — typically from gravity-bearing animals such as chicken, turkey, beef, bison, and lamb,” she writes. “Also helpful are eggs, dairy, and fish. In addition to having optimally balanced [amino acid] profiles, animal-based products are superior in calorie-for-calorie nutrient density. Moreover, their core nutrients are more bioavailable relative to plant foods.”

A vegetarian diet rich in dairy and eggs can theoretically provide a healthy dose of these essential amino acids, she notes. And even those who abstain completely from animal sources may be able to avoid a deficiency, though they may struggle to get enough. “If you choose lower-quality protein sources,” she says,” you will need to consume greater quantities or find supplemental options.”

Integrative physician Frank Lipman, MD, author of The New Rules of Aging Well, suggests a more plant-forward approach, arguing that too much leucine and other amino acids may suppress the mTOR mechanism’s ability to mediate autophagy, the body’s cellular recycling system. This dysregulation has been associated with a number of diseases, including arthritis, insulin resistance, and osteoporosis, as well as with various cancers and neurological disorders.

He recommends limiting our meat consumption to small portions two or three times a week while focusing more on protein from sources such as lentils, almonds, tempeh, and hemp powder. “I’m not suggesting you ditch animal protein altogether, but rather consider reframing your approach to animal protein,” he writes.

The mTOR question does require some nuance, Kriegler acknowledges. “It can be bad if it’s chronically stimulated, especially if it’s chronically stimulated in the context of elevated insulin levels and inflammation. That could be a recipe for cancer or other chronic metabolic illnesses.”

But, he adds, it’s our addiction to ultraprocessed foods that spikes insulin levels and triggers inflammation, so any debate over protein sources needs to occur within that context. “Both approaches are right,” he says. “You have to get enough protein, and stimulating mTOR periodically throughout the day isn’t bad. But it can be bad if it’s on top of a really bad foundation.”

 

Quality Matters

No matter where you choose to source your protein, Kriegler recommends that you make sure it comes from high-quality foods. On the animal front, that means opting for grassfed beef, free-range chicken, and wild-caught fish while avoiding factory-farmed and processed animal products.

For those enjoying plant-forward diets, look to organic, whole-ingredient foods such as tempeh and nuts rather than “impossible” meats and other ultraprocessed veggie fare.

Ramping up your consumption of high-quality protein as you age can offer myriad health benefits that extend far beyond keeping sarcopenia at bay. “Designing your diet around the protein quantity, quality, and distribution that meet the needs for muscle optimization will provide abundant amino acids for all these other essential functions, such as brain-cell communication, appetite regulation, and hormone production,” Lyon notes. “With a protein-forward approach, all other nutritional priorities fall into place.”

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