Correct, and the guideline on the "realfood.gov" site doesn't say it but all the protein g/kg body weight I've seen (mostly relative to weight training or building muscle) are in terms of kg of lean body mass, not total body weight.

All these things are actually rules of thumb that aim to be easy, and less focused on accurate.

A reasonably close rule of thumb can actually be 1g of protein per cm of height.

Also not accurately represented is that your body absorbs less protein per gram consumed the older you get. (I couldnt find a source with an actual ratio, just recommendations for _more_ as you get older).

When listening to folks like Layne Norton, they have said that surprisingly many people who simply increase their protein inadvertently begin to lose weight due to greater satiety per net calorie. (remember, roughly 20% of protein calories are lost in digesting/absorbing/converting the protein)

I am not 400lbs... I don't know if you are implying that... if so check your math:

1.2g/kg * 90kg (~200lbs-lean) = 108g of protein.

each person, on average, in the US would be eating one 16oz steak or 3-5 hamburgers every day.

> Doesn't make sense to me that a 400lb obese person would need to consume the same amount of protein as a 400lb lean muscle bodybuilder.

yeah both of those people are extreme cases that would break this very crude formula