Most physical therapists (PTs) routinely measure the vital signs. Heart rate, blood pressure, pulse oxygen, respiration rate, and often pain. But what about diet? Should diet be another vital sign? In the opinion of many scientists and medical experts diet ought to be a major vital sign that is measured by not only registered dietitians (RDs) and/or medical doctors (MDs), but also healthcare providers like PTs, on a routine basis.

What evidence do we have to say that diet ought to a basic vital sign? How about the fact that diet is the single leading predictor variable of all major health outcomes? The vast majority, roughly 80% according to the literature, of our diseases in the modern world are preventable and are caused by a poor diet. From cardiac disease, cancer, diabetes, and stroke, the injuries and diseases that lead to a patient ending up in a physical therapy clinic are likely preventable, if not reversible. 

But how does a PT measure diet as a vital sign? Many PTs who have...