This is a difficult question to answer since protein intake is based on a number of different criteria. Traditionally, recommendations have been based on bodyweight: one gram of protein per pound of bodyweight a day is a common recommendation. This recommendation is probably fine for most individuals who partake in typical year-round training; however, blanket recommendations for protein intake can sometimes be inaccurate when individuals have skewed bodyweight, like high body fat. Therefore, basing protein requirements on lean body mass (LBM) may be a more accurate method.
To become a little technical, adequate protein intake is dependent with the primary variables being body fat percentage (as this goes up, protein requirements go down), caloric intake (as caloric intake goes down, protein requirements go up and vice versa), and activity (with regular activity generally increasing protein requirements). A range can be given of anywhere from 1.5g/kg (0.68/lbs)of LBM for an obese untrained individual up to as high as 3.3g/kg (1.5g/lbs) of LBM for very lean heavily trained athletes or bodybuilders.
It is interesting to note that when individuals are looking to lose body fat, protein requirements generally increase. Just ask any body builder that is dieting down for a contest (noteworthy: bodybuilders are generally the most knowledgeable people in the fitness industry when it comes to nutrition. There are no other athletes that maintain 3-5% body fat when competing). The leaner an individual gets, the more protein they need, so protein requirements must be tweaked as individuals lose weight. This is to prevent the loss of lean body mass and blunt hunger. Studies show that protein is the most filling nutrient and that it helps control blood sugar which can help maintain energy levels and appetite when dieting.
Since most people don’t get enough protein in their diets to begin with, it is generally better to over consume protein than under consume it. For those who can’t be bothered measuring their food and counting their calories, a per-feeding quantity of protein may be easier. For example, trying to eat a lean protein source with each meal and eating at least 5 meals a day.