| there are a couple different formula's, but i like this one: 1 g of protein for each 1lb of lean body weight. This means that if you are 200 lbs and your BF% (body fat %) is 20%, then you should be eating 160g of protein.
200 lbs - (200 lbs * 20%) = 160g
or using: 100%-20%=80%
200 lbs * 80% = 160g
But, don't stress out about getting that much protein as it is surprisingly difficult to get there. Also, there may be a different calculation for women ... of that, I am not sure. | 
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