For decades, gym-goers and athletes were told a simple rule: eat 1 gram of protein per pound of body weight to build muscle. It was clean. Easy. Memorable. But then in 2018, a well-known meta-analysis claimed that anything above 1.6 grams per kilogram (g/kg) of body weight didn’t lead to additional muscle growth. That changed the conversation.

Since then, many have adopted that number as gospel. But recent research, including a deeper dive into the data behind that very study, shows things might not be so clear-cut. In fact, the evidence suggests we may be underestimating how much protein is truly optimal for muscle growth.

So, how much protein do you really need? Let’s break it down.

The 1.6 g/kg “Limit” Wasn’t Actually a Limit

The 2018 meta-analysis that sparked the shift toward 1.6 g/kg (around 0.73 g/lb) found what’s called a “breakpoint”, the amount at which more protein supposedly no longer yields more muscle. But there are two big problems with this conclusion:

1. The result wasn’t statistically significant.
   The breakpoint had a p-value of 0.079, meaning it doesn’t meet the standard scientific threshold (p < 0.05) for being reliable.
   
   

2. The range was wide.
   The true optimal intake might be anywhere from 1.03 to 2.20 g/kg, a huge range. This isn’t a precise target; it’s more like a foggy road sign that could point in multiple directions.
   
   

So the truth is: the 1.6 g/kg number wasn’t a hard cap at all. It was a best guess, one that may be too low.

Muscle Growth Continues Beyond 1.6 g/kg

If 1.6 g/kg were truly the limit, studies involving higher protein intakes shouldn’t show additional muscle gains. But they do.

Several studies have looked at participants already eating 1.6 g/kg or more, and found even greater gains when protein was increased further. Some of the most compelling evidence suggests gains continue at 2.0 to 2.2 g/kg, and may still inch upward all the way to 2.3 to 2.5 g/kg.

Yes, the extra benefits might get smaller the higher you go, but the upward trend is real. There doesn’t appear to be a sharp drop-off, just a gradual plateau.

So What’s the Real Sweet Spot?

A closer look at the full body of evidence points to 2.0 g/kg (0.9 g/lb) as a more accurate and reliable recommendation for maximizing muscle growth. Think of this as the “new normal” for lifters who want to be sure they’re not leaving gains on the table.

Here’s a practical range to keep in mind:

• Minimum for most trained individuals: 1.7 g/kg

• Optimal average for nearly everyone: 2.0 g/kg

• Safe upper limit: 2.3–2.5 g/kg
  
  

This range is supported by two different kinds of research:

• Long-term studies (where people lift and eat normally over weeks or months), and

• Short-term metabolic studies (like IAAO testing), which measure how much protein the body can effectively use.
  
  

In both, the trend is the same: around 2.0 g/kg is where most people thrive, and higher intakes are still safe and sometimes beneficial.

What About Women?

On average, women tend to benefit from slightly less protein than men, especially when accounting for differences in muscle mass and energy expenditure.

For most active women aiming to build or maintain muscle:

• Good target: 1.6–1.8 g/kg

• Upper buffer: 2.0–2.1 g/kg
  
  

It’s still a good idea to go a bit higher during fat loss phases or if training is particularly intense.

Should You Base Protein on Body Weight or Lean Mass?

Both work, but using lean body mass (LBM) can be more accurate, especially for those with high or low body fat percentages.

Here’s how it plays out:

• Standard approach (body weight):

• 2.0 g/kg (0.9 g/lb) is a solid general guideline.
  
  

• Lean mass approach:

• Aim for 2.3–2.5 g per kg of lean body mass.
  
  

You can calculate your lean mass by subtracting your estimated body fat from your total weight, but for most people, sticking to total body weight is just easier, and close enough.

When Cutting, More Protein Helps

When you’re in a calorie deficit, protein becomes even more important. Your body is at greater risk of losing muscle, and higher protein intakes help protect it.

During fat loss phases, studies suggest intakes of:

• 2.3–3.1 g/kg of lean mass, or

• 2.0–2.7 g/kg of body weight
  
  

These higher ranges aren’t just for bodybuilders. Even regular lifters and athletes benefit when trying to lose fat while preserving muscle.

So, What Should You Do?

Here’s your no-nonsense guide based on goals:

Final Thoughts

Protein is the building block of muscle, but the right amount matters. While 1.6 g/kg might be a decent starting point, the research clearly shows that 2.0 g/kg is more optimal, with benefits continuing beyond that for many individuals.

Whether you're trying to gain muscle, maintain it, or preserve it during fat loss, err on the higher side. There’s no harm in consuming slightly more than necessary, especially when compared to the risks of falling short.

And in case you're wondering: yes, the old-school “1 gram per pound” rule? It still holds up surprisingly well.