To build muscle, protein intake should generally be higher than the minimum recommended for sedentary adults. The key guidelines are:

• For maintaining muscle, about 1.2 grams of protein per kilogram of body weight per day is recommended.
• For building lean muscle mass, protein intake should increase to roughly 1.2 to 1.6 grams per kilogram of body weight.
• Strength athletes or those actively trying to gain muscle mass may need between 1.4 to 2.2 grams of protein per kilogram of body weight daily.
• Some experts suggest aiming for about 1.6 to 2.2 grams per kilogram for the first 12 weeks of a new workout program when muscle breakdown and rebuilding are most intense.
• If you know your lean body mass (total weight minus fat), targeting up to 2 grams of protein per kilogram of lean mass can be more precise for muscle gain.
• Older adults may benefit from slightly higher protein intake (around 1.0 g/kg) due to decreased absorption and muscle loss risk.

In practical terms, a person weighing 70 kg (154 lbs) aiming to build muscle might consume between 84 and 154 grams of protein daily, depending on their training intensity and goals

. It's important to balance protein intake with overall nutrition and not to excessively exceed these amounts, as very high protein intakes can stress the kidneys and may not further enhance muscle growth

. Summary:

Goal| Protein Intake (grams per kg body weight)
---|---
Maintain muscle| ~1.2 g/kg
Build muscle (general)| 1.2 – 1.6 g/kg
Build muscle (athletes)| 1.4 – 2.2 g/kg
Older adults (muscle loss prevention)| ~1.0 g/kg

This range provides an evidence-backed framework to optimize muscle growth through adequate protein consumption combined with strength training