Consensus on an appropriate quantity of protein seems hard to find, let alone consensus on which system of measurement to use - imperial or metric!
So here's a different approach: what is the minimum effective dose?
A Starting point:
Let's work backwards. Given protein's role in muscle building and maintenance, the minimum dose is that which allows people to maintain muscle mass.
Let's get one thing clear from the outset, the recommended daily intake (RDI) of 50-70g/day is insufficient. Campbell et al ran a great study analysing the effects of the RDI on elderly populations (so we're not even talking about a fitness population here), and found that over 14 weeks, their participants lost more muscle mass than normal. Imagine what that would do to a hard training individual!
Staying with elderly populations, research has determined that 1.5g of protein per KG of bodyweight is a reasonable amount to maintain normal health and fitness in elderly populations.
What about me?
...and what about in strength training or active people? turns out, similar amounts work perfectly! On ONE condition: adequate calorie intake.
For people trying to lose weight, an increase works better, up to 1.8g per Kg while you reduce the refined carbohydrates. Note, your doctor should be aware in order to advise on the appropriate amount of time for increased protein consumption. You get the best of both worlds: muscle mass maintenance, and weight loss (not to mention the satiating properties of protein, which make it easier to diet in the first place).
For those interested in general health benefits of Whey, like to boost immune system, improve sleep, focus, reduce fatigue or regulate blood sugar its also recommended to take be between 1 and 1.5 gr. per kg of body weight per day. (See article on health benefits)
Some concrete numbers:
So, if you're not losing weight and/or are trying to gain weight: 1.5g/kg of bodyweight is your minimum.
If you're after weight loss, this needs to go up to 1.8g/kg of bodyweight.
So there it is. For those of us in the pursuit of fitness, reaping the rewards of our training is important. To do this, a minimum of protein is required. Now you know what to do!
Take your protein seriously!