Why Protein Matters: A Guide to Building Muscle, Aging Well, and Staying Healthy

Protein and amino acids are essential nutrients that play a vital role in building and maintaining healthy muscle mass and connective tissues. Without adequate protein intake, it’s impossible to maintain or build the lean muscle mass needed for strength and vitality.

The Role of Protein in Longevity and Health

When considering longevity and health span, three critical factors are muscle mass, VO2 max (a measure of cardiovascular fitness), and metabolic health. Of these, muscle mass is especially important as we age. Many people considered frail in later life have lost significant muscle, which impacts their mobility and independence. The inability to perform daily tasks often comes from a lack of muscle strength—not just poor endurance.

Protein Supplementation and Muscle Maintenance

Research indicates that protein supplementation, such as incorporating protein shakes into a workout routine, can significantly enhance muscle mass, particularly in older adults. In one study, individuals aged 62 or older who were considered frail gained an average of three pounds of lean muscle mass through protein supplementation alongside strength training.

Unlike carbohydrates and fats, protein is not primarily used for energy. Our bodies rely on carbohydrates and fats to produce ATP (energy), while protein is used for building and repairing tissues. Only in extreme cases, such as starvation, does the body break down protein for energy, and this is not an efficient process. Moreover, protein isn’t stored in the body for future use; any excess is excreted as urea.

Protein Absorption and Aging

As we age, our bodies become less efficient at breaking down and absorbing protein from food. Therefore, older adults may actually need more protein than typically recommended to account for reduced bioavailability. For example, a healthy young adult may only absorb about 60% of the protein in a chicken breast, while someone in their seventies may absorb only 30–40%. This means that older adults often need to consume more protein to maintain their muscle mass.

Protein is made up of 20 amino acids, nine of which are essential—meaning our bodies cannot make them and they must be obtained from our diet. It’s essential to focus on obtaining all the necessary amino acids, rather than obsessing over specific types of protein, such as collagen.

How Much Protein Do You Really Need?

The standard U.S. dietary recommendation is 0.8 grams of protein per kilogram of body weight. However, this amount is enough only to meet basic survival needs—not for optimal health or muscle maintenance. Studies show that elderly individuals who consume only this amount often lose muscle mass, even over short periods, such as two weeks.

To thrive—especially as we age or become more physically active—we often require significantly more protein than the recommended minimum. Human studies have shown that low protein intake in older adults leads to muscle loss, increased mortality, and a reduced quality of life.

A good starting point is 1.6 grams of protein per kilogram of body weight per day. To convert your weight from pounds to kilograms, divide your weight by 2.2, then multiply by 1.6 to get your daily protein needs in grams. For active individuals with healthy kidney function, aiming for 1 gram of protein per pound of body weight is a simple and effective guideline. If that sounds like a lot, even three-quarters of a gram per pound is still beneficial.

Protein, Satiety, and Body Composition

Protein fills you up and leaves less room for excess carbohydrates. It leads to higher satiety because your body doesn’t want to use protein for fuel—it prefers to use it for building muscle, collagen, ligaments, tendons, hair, nails, and other tissues. As a result, your body uses stored fat for energy, especially if you are consuming enough protein to avoid starvation mode.

Most people don’t need to worry about getting too much protein; it would require a huge effort to overconsume. However, with age, anabolic resistance develops—meaning it becomes harder to build muscle, so you may need even more protein. There’s no wearable monitor for protein intake, so tracking your muscle mass and adjusting your intake accordingly is key.

Older individuals should monitor their lean mass, which can be measured using DEXA scans or body composition machines. If you notice muscle loss, increase your protein intake.

Practical Ways to Increase Protein Intake

One of the easiest ways to increase protein intake is by using whey protein, which is both affordable and efficient. For example, mixing a scoop of whey protein (approximately 20g) into yogurt (14g) can provide over 30 grams of protein in a single snack.

If you prefer plant-based protein, be aware that plant proteins are often less bioavailable due to being bound up with indigestible fiber. You may need to consume more and focus on key amino acids, such as leucine, lysine, and methionine, to maintain muscle mass.

Protein and Metabolic Health

Beyond building muscle, protein may benefit metabolism. Studies have shown that increasing protein intake can lower liver fat, improve insulin sensitivity, and enhance glucose control in individuals with type 2 diabetes. Eating protein helps you feel full, reduces the hunger hormone ghrelin, and can result in eating fewer calories overall.

The Takeaway

Don’t ignore protein. It’s the one macronutrient that is absolutely essential to your goals—especially as you age. There’s no minimum requirement for carbohydrates or fat, but a shortage of protein will cost you, particularly in later life.

Prioritize protein in your meals, track your muscle mass, and adjust your intake as needed to support a healthy, active lifestyle at any age.

•          The author, Rob Sumner, is a Doctor of Physical Therapy and owner of Sumner Specialized Physical Therapy. He's happy to answer any questions about this article, wellness, fitness, or physical therapy overall by phone at (509) 684-5621 or by email at Rob@SumnerPT.com