Final answer:
To determine protein balance, measure nitrogen intake and output or measure protein consumption in grams. Nitrogen balance is achieved when intake is equal to output. Animal proteins usually have higher biological value.
Step-by-step explanation:
To determine whether we are in protein balance, there are two methods that can be used.
The first method is by measuring the amount of nitrogen consumed with the amount of nitrogen excreted. This is known as nitrogen balance. If the intake of protein nitrogen exactly balances the loss of nitrogen in urine and feces, the individual is in protein balance. If there is more nitrogen intake than output, the individual is in a positive nitrogen balance, whereas if there is less intake than output, the individual is in a negative nitrogen balance.
The second method is by measuring the amount of protein consumed in grams. The biological value of a protein is a factor that is inversely proportional to the amount of a given protein source that must be consumed to keep an adult human in nitrogen balance. Animal proteins generally have a higher biological value compared to plant proteins.