Originally Posted by Derek Weaver
Where do you get your values from? I've seen everything from a similar range that you suggest, being closer to .6-1 gram per pound, all the way up to .8 as a minimum up to 1.5 grams/lb (closing in on 3.5 g/kg/day).
The two better sources I've seen are Lyle and Martin. Lyle researched an entire book on the subject of protein intake, and Martin is pretty meticulous with his research and writing on his site, and I'd assume on the book that's coming out someday.
To address the OP though, excess protein intake, regardless of health, tends to show diminishing returns. Through anecdotal evidence only, it seems that most do well around 1 gram/lb, occasionally a touch more.
You will only put on mass/weight through eating more and lifting progressively heavier weights.
Most of the popular sports nutrition books such as Anita Bean's and Nancy Clark's recommend a protein intake of 1.2-1.8g/kg of LBM/d which covers the needs of pretty much every athlete. The heavyweight texts like Exercise Physiology: Human Bioenergetics and it's Application
by Brooks, Fahey and Baldwin, Exercise Physiology: Energy Nutrition and Human Performance
by McArdle, Katch and Katch and Clinical Sports Nutrition
by Louise Burke give the same basic recommendation but break things down into more detail.
The two studies they all cite on this are Tarnopolsky et al (1988)
and Tarnopolsky et al(1992)
which show that nitrogen balance is maintained in strength/power athletes with protein intakes of 1-1.4g/kg/d and that endurance athletes have the greatest protein requirements.
In practice you don't need to be too concerned with your protein intake though because any reasonably varied diet will contain all the protein you need without the use of supplements providing your calorie intake is adequate.
I underlined that last part because it's important to remember that calories are the most critical ingredient in any weight gain program because a negative energy balance will always result in a negative nitrogen balance regardless of how much protein you eat.