The official U.S. RDA for protein is 0.8g per kilogram of bodyweight — about 54g a day for a 150lb person. That number is real, but it's also the single most misunderstood figure in nutrition science, because it was never designed to answer the question most people are actually asking.
What the RDA actually measures
The 0.8g/kg figure is the amount that prevents deficiency in a sedentary adult — the floor, not a target. It comes from nitrogen balance studies: researchers measure how much protein a person needs to eat before their body stops breaking down more muscle tissue than it rebuilds. That's a meaningful number for public health guidance aimed at an entire population, most of whom aren't training. It is not a number optimized for muscle growth, body composition, or athletic performance.
The range that actually matters for training
For anyone strength training regularly, the research consensus (International Society of Sports Nutrition, and separately confirmed by meta-analyses from Eric Helms' and Brad Schoenfeld's research groups) lands in a much higher band: 1.6-2.2g per kilogram of bodyweight per day. Above roughly 2.2g/kg, additional protein shows no further benefit for muscle protein synthesis in the studies that have tested it — this is the practical ceiling, not a floor to keep climbing past.
| Goal | Protein target | 150lb / 68kg person |
|---|---|---|
| Sedentary, general health | 0.8g/kg | ~54g/day |
| Weight loss, preserving muscle | 1.6-2.4g/kg | 109-163g/day |
| Muscle gain, resistance training | 1.6-2.2g/kg | 109-150g/day |
| Endurance athletes | 1.2-1.6g/kg | 82-109g/day |
| Adults over 65 | 1.0-1.2g/kg (higher if ill/injured) | 68-82g/day |
Why the target goes up during a cut, not down
This surprises a lot of people: protein needs actually increase in a calorie deficit, not decrease. When you're eating less overall, higher protein intake is one of the few reliable levers for preserving lean mass while losing fat — studies on caloric restriction consistently show better body-composition outcomes at the higher end of the 1.6-2.4g/kg range during a cut than at the low end.
The practical takeaway
If you're not training, 0.8g/kg is genuinely fine. If you lift weights with any regularity, multiply your bodyweight in kilograms by 1.6-2.2 and treat that as your daily target, adjusted toward the top of the range if you're actively cutting calories. Use the protein calculator on this site to get an exact number for your weight and goal.