Everyone has different daily protein needs, which can vary based on factors like age, weight, sex and physical activity level. As such, it can be difficult to know how much whey isolate to use, even though most brands include a plastic scoop and suggested serving size. If you can meet your minimum daily protein requirements with food alone -- and most Americans can -- you aren’t likely to need more than one scoop of isolate daily, and you may not need any at all.
How Much to Use
The simplest way to determine how much whey isolate to use is to calculate your approximate daily protein needs, find out about how much protein you already eat every day and then subtract the second number from the first. Most people don't have an accurate idea of how much protein they eat in an average day, but you can find out by keeping a detailed food journal for several days. Write down what you eat, use an online nutrition calculator to determine how much protein each food contains and take the average of each day's protein total.
Your Protein Needs
By taking inventory of the protein foods you eat every day, you can make an educated guess at how much protein you’re getting and determine whether you need whey isolate. Rice University recommends that average adults who are somewhat active eat between 0.4 and 0.6 gram of protein per pound of body weight per day. Very active athletes, especially strength athletes who are trying to put on lean muscle mass, may need up to 0.9 gram of protein per pound per day.
What Isolate Adds
Whey isolates contain more protein per serving than concentrate powders. According to Tom Venuto, personal trainer and certified strength and conditioning specialist, whey isolate is usually at least 90 percent protein by weight. That means in a typical 30-gram scoop, whey isolate may offer 26 grams of protein or more. If you weigh 150 pounds or less and are only moderately active, that’s about half of your daily protein requirements, so it may not be necessary to take a full scoop.
Do You Need It?
Whey isolate contains every amino acid that the human body needs and can’t produce by itself, but there are many other foods that offer the same. All animal- and milk-based proteins, including red meat, poultry, eggs, fish, cheese and yogurt, provide those essential amino acids, as does the plant-based soy. In fact, the International Society of Sports Nutrition suggests that healthy people get their protein from whole food sources rather than supplements whenever possible because whole foods offer greater overall nutrition.