How much protein do I need to build muscle? How much should I eat to maintain it later in life? Without question, the amount of protein you eat each day can have long-lasting effects on your health, fitness, and longevity.



To build muscle (or maintain it later in life), at a minimum, you need to:




eat enough protein



follow a well-designed strength training program



get adequate, quality sleep




Drop the ball on any of those three habits, and you say goodbye to your health-promoting, metabolism-stoking, longevity-supporting, good-looking muscle.



For most healthy people, I recommend a daily protein intake of 1.0 grams per pound ideal body weight. Here's why...





Protein digestion, assimilation, and metabolism



Amino acids are the building blocks of muscle.



Before you get any benefit from protein, you must break it down into amino acids and peptides.



Protein digestion begins in the stomach, where pepsin, hydrochloric acid, and digestive enzymes break protein bonds, leaving you with peptides and amino acids.



If your stomach isn't acidic enough or you don't have sufficient enzymes available, you cannot break protein down. This is why I encourage people to support their digestive system with supplemental enzymes.



Once the peptides and amino acids reach your small intestine, they get absorbed into your circulation.



Of the absorbed amino acids, 50-60% travel to the liver, where they're metabolized for other uses.



The remaining 40-50% gets used for energy and protein synthesis. Yet, of that amount, only a tiny fraction goes toward muscle growth.



One study showed that after a group of young, healthy men consumed 20 grams of high-quality protein, only about 2.2 grams was used for muscle growth. The rest was used for other metabolic functions.



You use dietary protein for much more than muscle growth. You use it for your immune system, building blood cells, tissue repair, and even creating neurotransmitters.



The recommended daily intake (RDI) for protein might be enough to avoid disease or starvation, but it isn't nearly enough for optimal health.



How age and sex affect protein needs



Older adults need more protein than younger adults to support the growth or maintenance of muscle.



As you age, you become less sensitive to protein intake, which means you need to eat significantly more to stimulate protein synthesis to the same degree you did when you were younger.



A 2015 study study comparing men in their 20s to men in their 70s showed that the older men needed to consume 68% more protein than the younger men to stimulate protein synthesis to the same extent.



That said when you see recommendations to consume a certain amount of protein, assume it's a recommendation for a young adult. Middle-aged adults could benefit from 35% more and older adults from 70% more protein than younger adults.



Research is unclear about the differences between the protein needs of men and women. However, muscle mass does increase sensitivity to amino acid intake.



As the average female has less muscle mass than the average male, I believe women would benefit from higher-protein intakes than men. However, that's just my belief.



Net Protein Balance, Muscle Protein Synthesis, and Muscle Protein Breakdown



Muscle mass is like a bank account. Your bank "balance" is equal to your deposits minus your withdrawals.



Your net muscle protein balance is equal to your muscle protein synthesis (MPS) minus your muscle protein breakdown (MPB). 



When muscle protein synthesis exceeds breakdown, you build muscle. 



When they're equal, you maintain muscle. 



When breakdown exceeds synthesis, you lose muscle.



To build muscle faster, you can increase protein synthesis to a greater extent, reduce protein breakdown to a greater extent, or do both.



You increase protein synthesis by:




Consuming optimal, high-quality protein



Strength training



Taking certain muscle-building supplements such a...