The protein target for building and keeping muscle is higher than most people assume, and most people who believe they eat a high-protein diet fall well short of it. Here are the numbers, what protein actually does in the body, what under-eating it costs, and how to hit the target across an ordinary day.
The Target, and the Gap
The established target for building and maintaining muscle is 1.6 to 2.2 grams of protein per kilogram of body weight per day.
That range is not a guess. A 2018 meta-analysis of 49 randomized controlled trials found the point where additional protein stopped producing additional muscle gain at 1.62 grams per kilogram per day. That figure is the floor for muscle-building.
Put it in food terms. For someone weighing 80 kilograms, about 176 pounds, the floor works out to roughly 130 grams of protein per day. That is a meaningful amount of food: three to four meals, each built around a substantial protein source.
Now the gap. Most people eating what they consider a high-protein diet are consuming around 70 to 90 grams per day. That is well below the floor. The distance between perceived high protein and actual high protein is large, and it is the single most common reason training does not produce the result the training itself would predict.
Building Material, Not Fuel
To understand why the target sits where it does, it helps to be clear on what protein is for.
Protein is not primarily a fuel source. Under most conditions the body runs on fat and carbohydrate for energy. Protein is the building material the body uses to construct and repair muscle, organs, enzymes, hormones, and immune cells.
When you eat it, the digestive system breaks it down into amino acids. Those amino acids enter the bloodstream and get directed wherever the body needs them, mostly toward repair and synthesis after training or the normal daily turnover of cells.
Two properties follow from this. First, protein is the most thermogenic macronutrient: the body burns roughly 20 to 30 percent of the calories in protein just digesting it, which is one reason higher-protein diets tend to reduce appetite and support fat loss. Second, excess protein does not get stored as body fat the way excess carbohydrate or fat can. When intake exceeds what the body can use for synthesis, the liver converts the surplus amino acids into glucose through a process called gluconeogenesis, the creation of new glucose, and the leftover nitrogen is filtered out and excreted.
What Under-Eating It Costs
Because protein is building material, falling short of the target has a structural cost that compounds quietly.
When intake drops below about 1.2 grams per kilogram per day, the rate at which the body breaks down muscle tissue can begin to outpace the rate at which it builds new tissue. The balance tips toward loss.
This is more pronounced with age. Older bodies require progressively more protein to produce the same muscle-building response, a phenomenon called anabolic resistance. The counterintuitive consequence is that older adults need higher protein intake to hold onto muscle, not lower, at exactly the age when appetite and intake tend to fall.
Chronic under-consumption shows up over time as slow training recovery, gradual muscle loss with age, weakened immune function, slower wound healing, hair thinning, and brittle nails. These symptoms are common, and they are rarely traced back to the underlying cause.
How to Actually Hit It
Total daily protein intake matters most. When you eat it across the day adds a smaller, real benefit on top.
Research on the muscle protein synthesis response suggests roughly 0.4 grams per kilogram per meal, across three to four meals, is a practical target for distribution. For an 80-kilogram person that is 30 to 35 grams of protein per meal. Spreading intake this way tends to support synthesis more consistently than eating most of the day's protein in one or two large meals.
For the food itself, animal proteins, meat, fish, eggs, and dairy, provide a complete amino acid profile and are used efficiently. A chicken breast, a can of tuna, three eggs, a cup of Greek yogurt, or a scoop of protein powder each deliver roughly 25 to 35 grams per serving. Plant proteins can meet the same needs but typically require larger volumes and a combination of different sources to cover all the essential amino acids.
The simplest way to operationalize all of it is one habit: anchor each meal around a clear protein source first, then build the rest of the meal around it. Most people do the reverse, assembling a meal and adding protein as an afterthought, and that is exactly how the 70-to-90-gram day happens.
If you do one thing with this, calculate your floor. Take your body weight in kilograms, multiply by 1.6, and you have your daily minimum in grams. Then, for two or three days, actually add up what you eat. The gap between the target and the honest count is the lever this post is about.
If you want more thinking like this, the Inner Navigation Framework is the Metaplexus newsletter, and it is free.